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PURPOSE: To evaluate the diagnostic performance of integrated whole-body positron emission tomography (PET)/magnetic resonance (MR) enterography in patients with Crohn's disease (CD). METHODS: Fifty patients with known CD and recurrent symptoms underwent ileocolonoscopy (reference standard) as well as PET/MR enterography. Seven ileocolonic segments were endoscopically analysed using the Simplified Endoscopic Activity Score for Crohn's Disease (SES-CD) and additionally classified into three categories of inflammation (none, mild to moderate and severe ulcerative inflammation). A total of 14 PET/MR parameters were applied for the assessment of inflamed segments. Contingency tables and the chi-squared test were used for the analysis of qualitative parameters, and the Mann-Whitney U test and receiver operating characteristic (ROC) curve for the analysis of quantitative parameters. The PET/MR parameters were ranked according to their diagnostic value by random forest classification. Correlations between PET/MR parameters and the severity of inflammation on endoscopy and SES-CD were tested using Spearman's rank correlation test. RESULTS: A total of 309 segments could be analysed. Based on multivariate regression analysis, wall thickness and the comb sign were the most important parameters for predicting segments with active inflammation of any type. SUVmax ratio of the bowel segment (relative to SUVmax of the liver) was the most important parameter for detecting segments with severe ulcerative inflammation. Wall thickness was the only parameter that moderately correlated with inflammation severity on endoscopy as well as with SES-CD (ρ = 0.56 and 0.589, both p < 0.001). CONCLUSION: PET/MR enterography is an excellent noninvasive diagnostic method, and both MR parameters and PET findings provided high accuracy in detecting inflamed segments.
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Doença de Crohn/diagnóstico por imagem , Imageamento por Ressonância Magnética , Tomografia por Emissão de Pósitrons , Fluordesoxiglucose F18 , Humanos , Inflamação , Estudos ProspectivosRESUMO
Background Considering the currently reported association between a repetitive application and cumulative dosage of Gadolinium (Gd)-based contrast agents and Gd-deposition in brain tissue as well as the risk for the advent of nephrogenic systemic fibrosis (NSF), techniques allowing for a dose reduction become an important key aspect aside from non-enhanced magnetic resonance angiography (MRA) techniques. Thus, this study was focused on the reduction and/or complete omission of contrast agent for renal MRA at 7T. Purpose To evaluate the performance of time-of-flight MRA versus low-dose contrast-enhanced (CE) renal MRA at 7T. Material and Methods Ten healthy volunteers were examined on a 7T MR system comprising a TOF MRA and three-dimensional (3D) fast low angle shot spoiled gradient-echo sequence (FLASH) MRA after administration of one-quarter of clinical dose of gadobutrol. Qualitative image analysis was performed including overall image quality, artery delineation and presence of artifacts. Contrast ratio (CR), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of the renal arteries were calculated. Results TOF MRA and low-CE MRA achieved comparable overall ratings, with slightly superior delineation of the main renal arteries in TOF MRA (TOF = 3.10 ± 0.75, low-CE = 2.95 ± 0.75). Segmental branches outside and inside the parenchyma were delineated significantly better on TOF MRA. Quantitative analysis demonstrated the superiority of TOF MRA, yielding higher scores for CR, SNR, and CNR. Conclusion The initial results of our study demonstrate the feasibility and comparable diagnostic performance of TOF and low-dose CE renal MRA at 7T.
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Meios de Contraste , Angiografia por Ressonância Magnética/métodos , Artéria Renal/diagnóstico por imagem , Adulto , Estudos de Viabilidade , Feminino , Humanos , Aumento da Imagem , Masculino , Adulto JovemRESUMO
OBJECTIVES: To compare the diagnostic performance of 68Ga-DOTATOC PET/MRI and 68Ga-DOTATOC PET/CT in the whole-body staging of patients with neuroendocrine tumours (NET). METHODS: Thirty patients with histopathologically confirmed NET underwent PET/CT and PET/MRI in a single-injection protocol. PET/CT and PET/MRI scans were prospectively evaluated with regard to lesion count, localization, nature (NET/non-NET), and conspicuity (four-point scale). Histopathology and follow-up imaging served as the reference standards. The proportions of NET and non-NET lesions rated correctly were compared using McNemar's chi-squared test. The Wilcoxon test was used to assess differences in SUVmax and lesion conspicuity. The correlation between the SUVmax for the same lesions from each modality was analysed using Pearson's correlation coefficient (r). RESULTS: According to the reference standard, there were 197 lesions (142 NET, 55 non-NET). Lesion-based analysis showed a higher proportion of correctly rated NET lesions on PET/MRI than on PET/CT (90.8% vs. 86.7%, p = 0.031), whereas on PET/CT there was a higher proportion of correctly rated non-NET lesions (94.5% vs. 83.6%, p = 0.031). SUVmax was strongly correlated (r = 0.86; p < 0.001) and did not differ significantly (p = 0.35) between the modalities. Overall conspicuity and NET lesion conspicuity were higher on PET/MRI (both p < 0.01). CONCLUSIONS: Ga-DOTATOC PET/MRI yielded a higher proportion of correctly rated NET lesions and should be regarded as a valuable alternative to 68Ga-DOTATOC PET/CT in whole-body staging of NET patients. KEY POINTS: ⢠68 Ga-DOTATOC PET/MRI correctly identified more NET lesions than 68 Ga-DOTATOC PET/CT. ⢠68 Ga-DOTATOC PET/MRI provides better NET lesion conspicuity than 68 Ga-DOTATOC PET/CT. ⢠SUVmax values from the two modalities are strongly correlated and do not differ significantly.
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Imageamento por Ressonância Magnética/métodos , Imagem Multimodal/métodos , Tumores Neuroendócrinos/diagnóstico por imagem , Octreotida/análogos & derivados , Compostos Organometálicos , Tomografia por Emissão de Pósitrons/métodos , Adulto , Idoso , Feminino , Radioisótopos de Gálio , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias/métodos , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Tomografia Computadorizada por Raios X/métodosRESUMO
OBJECTIVE: To evaluate the influence of Gadolinium contrast agent on image segmentation in magnetic resonance (MR)-based attenuation correction (AC) with four-segment dual-echo time Dixon-sequences in whole-body [18F]-fluorodeoxyglucose positron emission tomography (PET)/MR imaging, and to analyze the consecutive effect on standardized uptake value (SUV). MATERIALS AND METHODS: Hybrid imaging with an integrated PET/MR system was performed in 30 oncological patients. AC was based on MR imaging with a Dixon sequence with subsequent automated image segmentation. AC maps (µmaps) were acquired and reconstructed prior to (µmap-gd) and after (µmap+gd) Gd-contrast agent application. For quantification purposes, the SUV of organs and tumors based on both µmaps were compared. RESULTS: Tissue classification based on µmap-gd was correct in 29/30 patients; based on µmap+gd, the brain was falsely classified as fat in 12/30 patients with significant underestimation of SUV. In all cancerous lesions, tissue segmentation was correct. All concordant µmaps-gd/+gd resulted in no significant difference in SUV. CONCLUSION: In PET/MR, Gd-contrast agent potentially influences fat/water separation in Dixon-sequences of the head with above-average false tissue segmentation and an associated underestimation of SUV. Thus, MR-based AC should be acquired prior to Gd-contrast agent application. Additionally, integrating the MR-based AC maps into the reading-routine in PET/MR is recommended to avoid interpretation errors in cases where tissue segmentation fails.
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Fluordesoxiglucose F18 , Gadolínio , Imageamento por Ressonância Magnética/métodos , Neoplasias/tratamento farmacológico , Tomografia por Emissão de Pósitrons/métodos , Imagem Corporal Total/métodos , Adulto , Idoso , Meios de Contraste , Feminino , Humanos , Aumento da Imagem/métodos , Masculino , Pessoa de Meia-Idade , Imagem Multimodal/métodos , Compostos Radiofarmacêuticos , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
PURPOSE: In various tumours PET/CT with [(18)F]FDG is widely accepted as the diagnostic standard of care. The purpose of this study was to compare a dedicated [(18)F]FDG PET/MRI protocol with [(18)F]FDG PET/CT for TNM staging in a cohort of oncological patients. METHODS: A dedicated [(18)F]FDG PET/MRI protocol was performed in 73 consecutive patients (mean age of 59 years, range 21 - 85 years) with different histologically confirmed solid primary malignant tumours after a routine clinical FDG PET/CT scan (60 min after injection of 295 ± 45 MBq [(18)F]FDG). TNM staging according to the 7th edition of the AJCC Cancer Staging Manual was performed by two readers in separate sessions for PET/CT and PET/MRI images. Assessment of the primary tumour and nodal and distant metastases with FDG PET/CT and FDG PET/MRI was based on qualitative and quantitative analyses. Histopathology, and radiological and clinical follow-up served as the standards of reference. A McNemar test was performed to evaluate the differences in diagnostic performance between the imaging procedures. RESULTS: From FDG PET/CT and FDG PET/MRI T stage was correctly determined in 22 (82 %) and 20 (74 %) of 27 patients, N stage in 55 (82 %) and 56 (84 %) of 67 patients, and M stage in 32 (76 %) and 35 (83 %) of 42 patients, respectively. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy for lymph node metastases were 65 %, 94 %, 79 %, 89 % and 87 % for PET/CT, and 63 %, 94 %, 80 %, 87 % and 85 % for PET/MRI. The respective values for the detection of distant metastases were 50 %, 82 %, 40 %, 88 % and 76 % for PET/CT, and 50 %, 91 %, 57 %, 89 % and 83 % for PET/MRI. Differences between the two imaging modalities were not statistically significant (P > 0.05). CONCLUSION: According to our results, FDG PET/CT and FDG PET/MRI are of equal diagnostic accuracy for TNM staging in patients with solid tumours.
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Imageamento por Ressonância Magnética/normas , Imagem Multimodal/normas , Neoplasias/diagnóstico por imagem , Tomografia por Emissão de Pósitrons/normas , Tomografia Computadorizada por Raios X/normas , Imagem Corporal Total/normas , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Fluordesoxiglucose F18 , Humanos , Metástase Linfática/diagnóstico , Metástase Linfática/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Neoplasias/diagnóstico , Compostos Radiofarmacêuticos , Padrões de Referência , Sensibilidade e EspecificidadeRESUMO
PURPOSE: To evaluate the diagnostic potential of PET/MRI with [(18)F]FDG in recurrent ovarian and cervical cancer in comparison to PET/CT. METHODS: A group of 19 patients with suspected recurrence of pelvic malignancies (ovarian cancer, 11 patients; cervical cancer, 8 patients) scheduled for an [(18)F]FDG PET/CT were subsequently enrolled for a PET/MRI. The scan protocol comprised: (1) a T1-W axial VIBE after contrast agent adminstration, (2) an axial T2-W HASTE, (3) a coronal TIRM, (4) an axial DWI, and dedicated MR sequences of the female pelvis including (5) a T1-W VIBE before contrast agent adminstration, (6) a sagittal T2-W TSE, and (7) a sagittal T1-W dynamic VIBE. The datasets (PET/CT, PET/MRI) were rated separately by two readers regarding lesion count, lesion localization, lesion conspicuity (four-point scale), lesion characterization (benign/malignant/indeterminate) and diagnostic confidence (three-point scale). All available data (histology, prior examinations, PET/CT, PET/MRI, follow-up examinations) served as standard of reference. Median values were compared using the Wilcoxon rank sum test. RESULTS: Metastatic lesions were present in 16 of the 19 patients. A total of 78 lesions (malignant, 58; benign, 20) were described. Both PET/CT and PET/MRI allowed correct identification of all malignant lesions and provided equivalent conspicuity (3.86 ± 0.35 for PET/CT, 3.91 ± 0.28 for PET/MRI; p > 0.05). Diagnostic confidence was significantly higher for PET/MRI in malignant (p < 0.01) and benign lesions (p < 0.05). CONCLUSION: Both PET/CT and PET/MRI offer an equivalently high diagnostic value for recurrent pelvic malignancies. PET/MRI offers higher diagnostic confidence in the discrimination of benign and malignant lesions. Considering the reduced radiation dose and superior lesion discrimination, PET/MRI may serve as a powerful alternative to PET/CT in the future.
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Carcinoma/diagnóstico por imagem , Imageamento por Ressonância Magnética , Neoplasias Ovarianas/diagnóstico por imagem , Neoplasias Pélvicas/diagnóstico por imagem , Tomografia por Emissão de Pósitrons , Tomografia Computadorizada por Raios X , Neoplasias do Colo do Útero/diagnóstico por imagem , Adulto , Idoso , Carcinoma/patologia , Feminino , Fluordesoxiglucose F18 , Humanos , Metástase Linfática/diagnóstico por imagem , Pessoa de Meia-Idade , Imagem Multimodal , Estadiamento de Neoplasias , Neoplasias Ovarianas/patologia , Neoplasias Pélvicas/secundário , Compostos Radiofarmacêuticos , Neoplasias do Colo do Útero/patologia , Imagem Corporal TotalRESUMO
OBJECTIVES: To compare [(18)F]FDG PET/MRI with PET/CT for the assessment of bone lesions in oncologic patients. METHODS: This prospective study included 67 patients with solid tumours scheduled for PET/CT with [(18)F]FDG who also underwent a whole-body PET/MRI scan. The datasets (PET/CT, PET/MRI) were rated by two readers regarding lesion conspicuity (four-point scale) and diagnostic confidence (five-point scale). Median scores were compared using the Wilcoxon test. RESULTS: Bone metastases were present in ten patients (15%), and benign bone lesions in 15 patients (22%). Bone metastases were predominantly localized in the pelvis (18 lesions, 38%) and the spine (14 lesions, 29%). Benign bone lesions were exclusively osteosclerotic and smaller than the metastases (mean size 6 mm vs. 23 mm). While PET/CT allowed identification of 45 of 48 bone metastases (94%), PET/MRI allowed identification of all bone metastases (100%). Conspicuity of metastases was high for both modalities with significantly better results using PET/MRI (p < 0.05). Diagnostic confidence in lesion detection was high for both modalities without a significant difference. In benign lesions, conspicuity and diagnostic confidence were significantly higher with PET/CT (p < 0.05). CONCLUSIONS: [(18)F]FDG PET/MRI shows high potential for the assessment of bone metastases by offering superior lesion conspicuity when compared to PET/CT. In hypersclerotic, benign bone lesions PET/CT still sets the reference. KEY POINTS: ⢠PET/MRI and PET/CT are of equal value for the identification of disease-positive patients ⢠PET/MRI offers higher lesion conspicuity as well as diagnostic confidence ⢠PET/MRI is an attractive new alternative for the assessment of bone metastases.
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Neoplasias Ósseas/diagnóstico , Fluordesoxiglucose F18 , Imageamento por Ressonância Magnética/métodos , Tomografia por Emissão de Pósitrons/métodos , Tomografia Computadorizada por Raios X/métodos , Imagem Corporal Total/métodos , Neoplasias Ósseas/secundário , Diagnóstico Diferencial , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Estudos Prospectivos , Compostos Radiofarmacêuticos , Reprodutibilidade dos TestesRESUMO
PURPOSE: To assess the feasibility of hybrid imaging of the heart with fluorine 18 fluorodeoxyglucose (FDG) on an integrated 3-T positron emission tomography (PET)/magnetic resonance (MR) imaging system. MATERIALS AND METHODS: The present study was approved by the local institutional review board. Written informed consent was obtained from all patients before imaging. Twenty consecutive patients with myocardial infarction (n = 20) underwent cardiac PET/MR imaging examination. Ten patients underwent additional cardiac PET/computed tomography (CT) before PET/MR. Two-dimensional half-Fourier acquisition single-shot turbo spin-echo sequences, balanced steady-state free precession cine sequences, two-dimensional turbo inversion-recovery magnitude T2-weighted sequences, and late gadolinium-enhanced (LGE) segmented two-dimensional inversion-recovery turbo fast low-angle shot sequences were performed. According to the 17-segment model, PET tracer uptake, wall motion, and late gadolinium enhancement were visually assessed for each segment on a binary scale, and categorical intermethod agreement was calculated by using the Cohen κ. The maximum standardized uptake value was measured in corresponding myocardial locations on PET/CT and PET/MR images. RESULTS: Agreement was substantial over all patients and segments between PET and LGE images (κ = 0.76) and between PET and cine images (κ = 0.78). In 306 segments, 97 (32%) were rated as infarcted on PET images, compared with 93 (30%) rated as infarcted on LGE images and with 90 (29%) rated as infarcted on cine images. In a subgroup of patients (n = 10) with an additional PET/CT scan, no significant difference in myocardial tracer uptake between PET/CT and PET/MR images was found (paired t test, P = .95). CONCLUSION: Cardiac PET/MR imaging with FDG is feasible and may add complementary information in patients with ischemic heart disease.
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Imagem Cinética por Ressonância Magnética/métodos , Infarto do Miocárdio/patologia , Tomografia por Emissão de Pósitrons/métodos , Técnicas de Imagem de Sincronização Cardíaca , Meios de Contraste , Estudos de Viabilidade , Feminino , Fluordesoxiglucose F18 , Humanos , Masculino , Pessoa de Meia-Idade , Imagem Multimodal , Infarto do Miocárdio/diagnóstico por imagem , Compostos Organometálicos , Compostos Radiofarmacêuticos , Tomografia Computadorizada por Raios XRESUMO
PURPOSE: The technically caused delay between low-energy (LE) and high-energy (HE) acquisitions allows motion artifacts in contrast-enhanced dual-energy mammography (CEDEM). In this study the effect of motion correction by nonrigid registration on image quality of the recombined images was investigated. MATERIALS AND METHODS: Retrospectively for 354 recombined CEDEM images an additional recombined image was processed from the raw data of LE and HE images using the motion correction algorithm. Five radiologists with many years of experience in breast cancer diagnostic imaging compared side-by-side one conventional processed CEDEM image with the corresponding image processed by the motion correction algorithm. Every pair of images was compared based on six criteria: General image quality (1), sharpness of skin contour (2), reduction of image artifacts (3), sharpness of lesion contour (4), contrast of lesion (5), visibility of lymph nodes (6). These criteria were rated on a Likert scale (improvement: +â1, +â2; deterioration: -1, -2). RESULTS: The mean ratings concerning criteria 1-5 showed a superiority of the recombined images processed by the motion correction algorithm. For example, the mean rating of general image quality was 0.86 (95â% CI: 0.78; 0.93). Only the mean rating concerning criterion 6 showed an inferiority of the recombined images processed by the motion correction algorithm (-0.29 (-0.46; -0.13)). CONCLUSION: The usage of nonrigid registration for motion correction significantly improves the general image quality and the quality of subordinate criteria on the recombined CEDEM images at the expense of somewhat reduced lymph node visibility in some cases. KEY POINTS: · The usage of motion correction in CEDEM improves the general image quality. · Motion correction might have the potential to increase diagnostic accuracy. · Alternative methods of motion artifact reduction are not yet available in clinical practice. CITATION FORMAT: · Sistermanns M, Kowall B, Hörnig M etâal. Motion Artifact Reduction in Contrast-Enhanced Dual-Energy Mammography - A Multireader Study about the Effect of Nonrigid Registration as Motion Correction on Image Quality. Fortschr Röntgenstr 2021; 193: 1183â-â1188.
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Artefatos , Mamografia , Algoritmos , Humanos , Movimento (Física) , Estudos RetrospectivosRESUMO
Background: To investigate the diagnostic performance of simultaneous 18F-fluoro-deoxyglucose ([18F]-FDG) PET/MR enterography in assessing and grading endoscopically active inflammation in patients with ulcerative colitis. Methods: 50 patients underwent PET/MR 24 h before ileocolonoscopy. Inflammatory activities of bowel segments were evaluated with both Mayo endoscopic subscore and Nancy histologic index. MR, DWI (Diffusion-weighted imaging) and PET were utilized as qualitative parameters for detecting endoscopically active inflammation. SUVmaxQuot in each segment (maximum of standard uptake value relative to liver) was calculated to quantify inflammation. Results: In the study arm without bowel purgation, combined reading of PET and MR resulted in significantly increased specificity against each submodality alone (0.944 vs. 0.82 for MR and 0.843 for PET, p < 0.05) and highest overall accuracy. In the study arm with bowel purgation, the significantly lower specificity of PET (0.595) could be markedly improved by a combined reading of PET and MR. Metabolic conditions in bowel segments with both endoscopic and histological remission were significantly lower than in segments with endoscopic remission but persistent microscopic inflammation (SUVmaxQuot 0.719 vs. 0.947, p < 0.001). SUVmaxQuot correlated highly with Mayo endoscopic subscore (ρ = 0.718 and 0.606) and enabled grading of inflammatory activity. Conclusions: Simultaneous [18F]-FDG PET/MR may be considered as an alternative to endoscopy in clinical trials.
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Our objective was to define an 18F-FDG PET/MR enterography index as a hybrid surrogate marker for active ileocolonic inflammation in Crohn's disease (CD) and assess its diagnostic performance in comparison to validated MR indices (MR index of activity [MaRIA], Clermont score). Methods: Fifty-two CD patients with recurrent symptoms underwent ileocolonoscopy and 18F-FDG PET/MR enterography. Three hundred three ileocolonic segments were assessed for inflammation using MaRIA and the Clermont score as well as the newly defined PET/MR index. On the basis of tobit regression, the PET/MR index was defined as (0.87 × wall thickness) + (1.97 × edema) + (0.83 × ulceration) + (0.55 × SUVmax ratio) + 1.14. The endoscopic activity of inflammation was determined by the simplified endoscopic activity score for CD (SES-CD). Receiver-operating-characteristic curves for each surrogate marker were created and tested against each other using the DeLong test, and diagnostic accuracies were compared using the McNemar test. Correlations between surrogate markers and SES-CD were tested with the Spearman rank correlation test. Results: The PET/MR index showed a comparable sensitivity but a significantly higher specificity and accuracy than MaRIA and the Clermont score in predicting both active and severe inflammation (active inflammation: specificities of 0.933, 0.711, and 0.707 and accuracies of 0.921, 0.739, and 0.736, P < 0.001; severe inflammation: specificities of 0.91, 0.81, and 0.785 and accuracies of 0.914, 0.818, and 0.795, P < 0.01, respectively). All surrogate markers correlated moderately with SES-CD on a segmental basis and a global level (0.5 < ρ < 0.7, all P < 0.001). Conclusion: As a hybrid surrogate marker comprising MR parameters and the PET component, the PET/MR index yielded significantly improved specificity and diagnostic accuracy compared with conventional MR indices (MaRIA and the Clermont score), demonstrating its high potential for noninvasive assessment of CD.
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Colo/diagnóstico por imagem , Doença de Crohn/diagnóstico por imagem , Íleo/diagnóstico por imagem , Imageamento por Ressonância Magnética , Imagem Multimodal , Tomografia por Emissão de Pósitrons , Adulto , Idoso , Colo/patologia , Doença de Crohn/patologia , Estudos de Viabilidade , Feminino , Fluordesoxiglucose F18 , Humanos , Íleo/patologia , Processamento de Imagem Assistida por Computador , Inflamação/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
OBJECTIVES: To evaluate the added value of the application of the liver-specific contrast phase of Gadobenate dimeglumine (Gd-BOPTA) for detection and characterization of liver lesions in 18F-FDG PET/MRI. METHODS: 41 patients with histologically confirmed solid tumors and known / suspected liver metastases or not classifiable lesions in 18F-FDG PET/CT were included in this study. All patients underwent a subsequent Gd-BOPTA enhanced 18F-FDG PET/MRI examination. MRI without liver-specific contrast phase (MRI1), MRI with liver-specific contrast phase (MRI2), 18F-FDG PET/MRI without liver-specific contrast phase (PET/MRI1) and with liver-specific contrast phase (PET/MRI2) were separately evaluated for suspect lesions regarding lesion dignity, characterization, conspicuity and confidence. RESULTS: PET/MRI datasets enabled correct identification of 18/18 patients with malignant lesions; MRI datasets correctly identified 17/18 patients. On a lesion-based analysis PET/MRI2 provided highest accuracy for differentiation of lesions into malignant and benign lesions of 98% and 100%. Respective values were 95% and 100% for PET/MRI1, 93% and 96% for MRI2 and 91% and 93% for MRI1. Statistically significant higher diagnostic confidence was found for PET/MRI2 and MRI2 datasets compared to PET/MRI1 and MRI1, respectively (p < 0.001). CONCLUSION: The application of the liver-specific contrast phase in 18F-FDG PET/MRI further increases the diagnostic accuracy and diagnostic confidence for correct assessment of benign and malignant liver lesions.
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Carcinoma Hepatocelular/diagnóstico por imagem , Meios de Contraste/farmacocinética , Neoplasias Hepáticas/diagnóstico por imagem , Fígado/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Meglumina/análogos & derivados , Compostos Organometálicos/farmacocinética , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Adulto , Idoso , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/secundário , Colangiocarcinoma/diagnóstico por imagem , Colangiocarcinoma/metabolismo , Colangiocarcinoma/patologia , Neoplasias Colorretais/diagnóstico por imagem , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Feminino , Fluordesoxiglucose F18/farmacocinética , Humanos , Fígado/metabolismo , Fígado/patologia , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/secundário , Masculino , Meglumina/farmacocinética , Melanoma/diagnóstico por imagem , Melanoma/metabolismo , Melanoma/patologia , Pessoa de Meia-Idade , Compostos Radiofarmacêuticos/farmacocinética , Sensibilidade e EspecificidadeRESUMO
OBJECTIVES: The aim of this study was to investigate and compare the feasibility as well as potential impact of altered magnetic field properties on image quality and potential artifacts of 1.5 Tesla, 3 Tesla and 7 Tesla non-enhanced abdominal MRI. MATERIALS AND METHODS: Magnetic Resonance (MR) imaging of the upper abdomen was performed in 10 healthy volunteers on a 1.5 Tesla, a 3 Tesla and a 7 Tesla MR system. The study protocol comprised a (1) T1-weighted fat-saturated spoiled gradient-echo sequence (2D FLASH), (2) T1-weighted fat-saturated volumetric interpolated breath hold examination sequence (3D VIBE), (3) T1-weighted 2D in and opposed phase sequence, (4) True fast imaging with steady-state precession sequence (TrueFISP) and (5) T2-weighted turbo spin-echo (TSE) sequence. For comparison reasons field of view and acquisition times were kept comparable for each correlating sequence at all three field strengths, while trying to achieve the highest possible spatial resolution. Qualitative and quantitative analyses were tested for significant differences. RESULTS: While 1.5 and 3 Tesla MRI revealed comparable results in all assessed features and sequences, 7 Tesla MRI yielded considerable differences in T1 and T2 weighted imaging. Benefits of 7 Tesla MRI encompassed an increased higher spatial resolution and a non-enhanced hyperintense vessel signal at 7 Tesla, potentially offering a more accurate diagnosis of abdominal parenchymatous and vasculature disease. 7 Tesla MRI was also shown to be more impaired by artifacts, including residual B1 inhomogeneities, susceptibility and chemical shift artifacts, resulting in reduced overall image quality and overall image impairment ratings. While 1.5 and 3 Tesla T2w imaging showed equivalently high image quality, 7 Tesla revealed strong impairments in its diagnostic value. CONCLUSIONS: Our results demonstrate the feasibility and overall comparable imaging ability of T1-weighted 7 Tesla abdominal MRI towards 3 Tesla and 1.5 Tesla MRI, yielding a promising diagnostic potential for non-enhanced Magnetic Resonance Angiography (MRA). 1.5 Tesla and 3 Tesla offer comparably high-quality T2w imaging, showing superior diagnostic quality over 7 Tesla MRI.
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Abdome/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Adulto , Feminino , Voluntários Saudáveis , Humanos , MasculinoRESUMO
OBJECTIVES: To investigate whether a dose reduction of Gadobutrol for renal magnetic resonance angiography (MRA) at 7 Tesla (T) is feasible while preserving diagnostic image quality. METHODS: Ten healthy volunteers were enrolled for a renal MRA on a 7T scanner. Fast low angle shot (FLASH) MRA data sets were obtained utilizing three different doses of Gadobutrol (0.1, 0.05 and 0.025mmol/kg body weight [BW]). Contrast ratios (CR) were measured in the aorta as well as in the intra- and extraparenchymal arteries compared to the psoas muscle. Qualitative analysis regarding the delineation of vessel structures was performed using a four-point-scale. RESULTS: All doses of Gadobutrol allowed for a good delineation of the aorta and renal arteries. For the extra- and intraparenchymal segmental arteries higher values were observed for full and half dose in comparison to quarter dose. No significant difference was observed for full and half dose. A lower CR was observed for quarter compared to half dose (p<0.05) for the renal arteries. CONCLUSIONS: While best results were observed for half and full dose, a dose reduction to 0.025mmol/kg BW is justifiable, maintaining a diagnostic image quality. This may be of high interest considering patients with renal impairment.
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Meios de Contraste , Gadolínio , Angiografia por Ressonância Magnética/métodos , Artéria Renal/anatomia & histologia , Adulto , Aorta Abdominal/anatomia & histologia , Artefatos , Relação Dose-Resposta a Droga , Estudos de Viabilidade , Feminino , Voluntários Saudáveis , Humanos , Masculino , Compostos Organometálicos , Estudos Prospectivos , Adulto JovemRESUMO
This study evaluated the impact of 68Ga-DOTATOC PET/CT in detecting recurrence or metastases in differentiated thyroid carcinoma (DTC) patients with elevated serum thyroglobulin and both negative radioiodine imaging and negative 18F-FDG PET/CT. METHODS: 68Ga-DOTATOC PET/CT (CT without contrast, low-dose) was performed on average 6 wk after negative 18F-FDG PET/CT (CT contrast-enhanced, full-dose) in 15 consecutive radioiodine-negative DTC patients with elevated and rising thyroglobulin. Visual assessment of 68Ga-DOTATOC PET/CT images used a 4-point scale for classification of lesions (0, no pathologic findings; 1, benign; 2, equivocal; 3, malignant). PET findings were correlated with the histologic subtype of tumor, levels of serum thyroglobulin, and morphologic findings on full-dose CT and neck ultrasound. Histology or clinical and imaging follow-up served as a reference standard. Analysis was performed on a patient and lesion basis. RESULTS: 68Ga-DOTATOC PET/CT was true-positive in 5 patients (10 tumor lesions) and was false-positive in 1 patient. The rate of positive 68Ga-DOTATOC PET/CT was significantly higher in poorly differentiated/oxyphilic carcinomas (4/4 patients) than in papillary (1/5) or follicular (0/6) tumors. Thyroglobulin levels tended to be higher in patients with tumor localization on 68Ga-DOTATOC PET/CT, but differences were not significant. In 2 of 5 patients with true-positive findings on 68Ga-DOTATOC PET/CT, CT alone but not ultrasound identified 2 of 10 tumor lesions, but in both patients 68Ga-DOTATOC-PET/CT revealed further tumor lesions not detected on CT alone. CONCLUSION: 68Ga-DOTATOC PET/CT should be considered in the case of negative 18F-FDG PET/CT in radioiodine-negative DTC patients with elevated and rising thyroglobulin. Imaging with 68Ga-DOTATOC appears promising especially in poorly differentiated and oxyphilic subtypes of DTC.
Assuntos
Fluordesoxiglucose F18 , Radioisótopos do Iodo , Octreotida/análogos & derivados , Compostos Organometálicos , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Tireoglobulina/sangue , Neoplasias da Glândula Tireoide/sangue , Neoplasias da Glândula Tireoide/diagnóstico por imagem , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Neoplasias da Glândula Tireoide/patologia , Adulto JovemRESUMO
PURPOSE: To implement a protocol for PET/MR enterography for a multimodal assessment of intestinal pathologies. MATERIALS AND METHODS: 19 patients with bowel malignancies, Crohn's disease or fever of unknown origin (male: n=14, female: n=5, age: 57±13years) underwent PET/MR enterography with either [(18)F]FDG (n=10) or [(68)Ga]-DOTATOC (n=9) using an integrated scanner. For small bowel distension a contrast solution (1500 cm(3) of mannitol and locust bean gum) was ingested. The following sequences were acquired: (a) coronal TrueFISP; (b) coronal T2w HASTE; (c) coronal dynamic T1w VIBE; (d) axial and coronal T1w FLASH post gadolinium. All datasets were reviewed by two readers with regard to co-registration of anatomical structures based on a 3-point ordinal scale as well as overall image quality using a 4-point ordinal scale. Furthermore, visualization of intestinal and extra-intestinal pathologies was assessed. RESULTS: PET/MR enterography was well tolerated by all patients. High overall MR image quality was achieved (mean score: 3.2±0.6) with good co-registration of PET and MRI (mean scores: 2.6 to 3.0). PET/MR enterography allowed for an excellent visualization of both intestinal as well as extra-intestinal pathologies. CONCLUSION: PET/MR enterography is technically feasible and offers good co-registration of bowel structures. This novel method enables a multimodal assessment of bowel lesions in malignant and inflammatory disease.
Assuntos
Enteropatias/diagnóstico por imagem , Enteropatias/patologia , Imageamento por Ressonância Magnética/métodos , Imagem Multimodal/métodos , Tomografia por Emissão de Pósitrons/métodos , Meios de Contraste , Estudos de Viabilidade , Feminino , Fluordesoxiglucose F18 , Radioisótopos de Gálio , Humanos , Aumento da Imagem , Intestinos/diagnóstico por imagem , Intestinos/patologia , Masculino , Pessoa de Meia-Idade , Octreotida/análogos & derivados , Compostos RadiofarmacêuticosRESUMO
UNLABELLED: The aim of this study was to systematically assess the quantitative and qualitative impact of including point-spread function (PSF) modeling into the process of iterative PET image reconstruction in integrated PET/MR imaging. METHODS: All measurements were performed on an integrated whole-body PET/MR system. Three substudies were performed: an (18)F-filled Jaszczak phantom was measured, and the impact of including PSF modeling in ordinary Poisson ordered-subset expectation maximization reconstruction on quantitative accuracy and image noise was evaluated for a range of radial phantom positions, iteration numbers, and postreconstruction smoothing settings; 5 representative datasets from a patient population (total n = 20, all oncologic (18)F-FDG PET/MR) were selected, and the impact of PSF on lesion activity concentration and image noise for various iteration numbers and postsmoothing settings was evaluated; and for all 20 patients, the influence of PSF modeling was investigated on visual image quality and number of detected lesions, both assessed by clinical experts. Additionally, the influence on objective metrics such as changes in SUVmean, SUVpeak, SUVmax, and lesion volume was assessed using the manufacturer-recommended reconstruction settings. RESULTS: In the phantom study, PSF modeling significantly improved activity recovery and reduced the image noise at all radial positions. This effect was measurable only at a high number of iterations (>10 iterations, 21 subsets). In the patient study, again, PSF increased the detected activity in the patient's lesions at concurrently reduced image noise. Contrary to the phantom results, the effect was notable already at a lower number of iterations (>1 iteration, 21 subsets). Lastly, for all 20 patients, when PSF and no-PSF reconstructions were compared, an identical number of congruent lesions was found. The overall image quality of the PSF reconstructions was rated better when compared with no-PSF data. The SUVs of the detected lesions with PSF were substantially increased in the range of 6%-75%, 5%-131%, and 5%-148% for SUVmean, SUVpeak, and SUVmax, respectively. A regression analysis showed that the relative increase in SUVmean/peak/max decreases with increasing lesion size, whereas it increases with the distance from the center of the PET field of view. CONCLUSION: In whole-body PET/MR hybrid imaging, PSF-based PET reconstructions can improve activity recovery and image noise, especially at lateral positions of the PET field of view. This has been demonstrated quantitatively in phantom experiments as well as in patient imaging, for which additionally an improvement of image quality could be observed.
Assuntos
Imageamento por Ressonância Magnética , Modelos Teóricos , Imagem Multimodal , Tomografia por Emissão de Pósitrons , Adulto , Idoso , Feminino , Fluordesoxiglucose F18 , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Pessoa de Meia-Idade , Neoplasias/diagnóstico por imagem , Imagens de FantasmasRESUMO
OBJECTIVE: To evaluate different magnetic resonance (MR) imaging sequences in integrated positron emission tomography (PET)/MR concerning their ability to detect tumors and allocate increased radionuclide uptake on (18)F-fluorodeoxyglucose ((18)F-FDG) PET in intraindividual comparison with computed tomography (CT) from PET/CT. MATERIAL AND METHODS: Sixty-one patients (34 female, 27 male, mean age 57.6 y) who were examined with contrast-enhanced PET/CT and subsequent PET/MR (mean delay for PET/MR after injection: 147 ± 43 min) were included. A maximum of ten (18)F-FDG-avid lesions per patient were analyzed on CT from PET/CT and with the following MR sequences from PET/MR: T2, turbo inversion recovery magnitude (TIRM), non-enhanced T1, contrast-enhanced T1, and diffusion-weighted imaging (DWI). All lesions were rated using a four-point ordinal scale (scored from 0 to 3) concerning visual detectability of the lesion against the surrounding background and anatomical allocation of the PET finding. In each category (detectability and allocation), Wilcoxon rank sum tests were performed. Bonferroni-Holm correction was performed to prevent α-error accumulation. RESULTS: In 225 (18)F-FDG-avid lesions (156 confirmed as malignant by radiological follow up, 69 by histopathology), visual detectability was comparably high on CT (mean: 2.5 ± 0.9), TIRM (mean: 2.5 ± 0.9), T2 (mean: 2.4 ± 0.9), and DWI (mean: 2.5 ± 1.0) and was significantly higher than on non-enhanced T1 (mean: 2.2 ± 1.0). While anatomic allocation of the PET finding was comparable with CT (mean: 2.6 ± 0.7), T2 (mean: 2.6 ± 0.7), and TIRM (mean: 2.8 ± 0.7), it was significantly higher compared to DWI (mean: 2.1 ± 1.0) and non-enhanced T1 (mean: 2.4 ± 0.8). CONCLUSION: In conclusion, T2, TIRM, and contrast-enhanced T1 provide a high quality of lesion detectability and anatomical allocation of FDG-avid foci. Their performance is at least comparable to contrast-enhanced PET/CT. Non-enhanced T1 may be omitted and the necessity of DWI should be further investigated for specific questions, such as assessment of the liver.
Assuntos
Imagem de Difusão por Ressonância Magnética , Imagem Multimodal/métodos , Neoplasias/diagnóstico , Tomografia por Emissão de Pósitrons , Tomografia Computadorizada por Raios X , Imagem Corporal Total/métodos , Feminino , Fluordesoxiglucose F18 , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/patologia , Tomografia por Emissão de Pósitrons/métodosRESUMO
OBJECTIVE: The biologically active molecule used in positron emission tomography (PET) for depiction of osteoblastic activity is 18F-labeled fluoride (18F-F). We examined whether inflammatory or chronic changes on magnetic resonance imaging (MRI) in the sacroiliac joints (SIJ) and the spines of patients with active ankylosing spondylitis (AS) are linked to osteoblastic activity, assessed by PET/MRI. METHODS: Thirteen patients with AS (mean age 37.8 ± 11.4 yrs, Bath AS Disease Activity Index > 4, no anti-TNF treatment) underwent 3-Tesla whole-spine and SIJ PET/MRI. Two independent readers recorded pathologic changes related to vertebral (VQ) or SIJ quadrants (SQ). Final scores were based on reader agreement. RESULTS: A total of 104 SQ and 1196 VQ were examined. In SIJ, bone marrow edema (BME) was seen in 44.2%, fat deposition (FD) in 42.3%, and 18F-F in 46.2% SQ. BME alone was associated with 18F-F in 78.6% and FD alone in only 7.7% SQ, while the combination BME/FD was associated with 18F-F in 72.2% SQ. Erosions, sclerosis, and ankylosis alone were rarely associated with 18F-F. In the spine, BME alone was seen in 9.9%, FD in 18.2%, and 18F-F in 5.4% VQ. BME alone was associated with 18F-F in 14.3% and FD alone in 8.7% VQ, while the combination BME/FD was associated with 18F-F in 40.6% VQ. CONCLUSION: In this study of hybrid 18F-F PET/MRI of patients with active AS, we show that BME rather than chronic changes is associated with osteoblastic activity, while the combination of BME and FD showed the highest 18F-F uptake. The use of PET/MRI in prediction of future syndesmophyte formation in AS needs further exploration in prospective studies.
Assuntos
Osteoblastos/diagnóstico por imagem , Articulação Sacroilíaca/diagnóstico por imagem , Coluna Vertebral/diagnóstico por imagem , Espondilartrite/diagnóstico por imagem , Adulto , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Osteoblastos/patologia , Projetos Piloto , Tomografia por Emissão de Pósitrons , Articulação Sacroilíaca/patologia , Coluna Vertebral/patologia , Espondilartrite/patologiaRESUMO
BACKGROUND: The aim of this study was to compare the diagnostic accuracy of [18F]FDG-PET/MRI with PET/CT for the detection of liver metastases. METHODS: 32 patients with solid malignancies underwent [18F]FDG-PET/CT and subsequent PET/MRI of the liver. Two readers assessed both datasets regarding lesion characterization (benign, indeterminate, malignant), conspicuity and diagnostic confidence. An imaging follow-up (mean interval: 185±92 days) and/-or histopathological specimen served as standards of reference. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for both modalities. Accuracy was determined by calculating the area under the receiver operating characteristic (ROC) curve. Values of conspicuity and diagnostic confidence were compared using Wilcoxon-signed-rank test. RESULTS: The standard of reference revealed 113 liver lesions in 26 patients (malignant: n = 45; benign: n = 68). For PET/MRI a higher accuracy (PET/CT: 82.4%; PET/MRI: 96.1%; p<0.001) as well as sensitivity (67.8% vs. 92.2%, p<0.01) and NPV (82.0% vs. 95.1%, p<0.05) were observed. PET/MRI offered higher lesion conspicuity (PET/CT: 2.0±1.1 [median: 2; range 0-3]; PET/MRI: 2.8±0.5 [median: 3; range 0-3]; p<0.001) and diagnostic confidence (PET/CT: 2.0±0.8 [median: 2; range: 1-3]; PET/MRI 2.6±0.6 [median: 3; range: 1-3]; p<0.001). Furthermore, PET/MRI enabled the detection of additional PET-negative metastases (reader 1: 10; reader 2: 12). CONCLUSIONS: PET/MRI offers higher diagnostic accuracy compared to PET/CT for the detection of liver metastases.