Radiation exposure, organ and effective dose of CT-guided liver biopsy as a function of lesion depth and size.

Computed tomography (CT)-guided percutaneous biopsies play an important role in the diagnostic workup of liver lesions. Because radiation dose accumulates rapidly due to repeated image acquisition in a relatively small scan area, analysing radiation exposure is critical for improving radiation protection of CT-guided interventions. The aim of this study was to assess the radiation dose of CT-guided liver biopsies and the influence of lesion parameters, and to establish a local diagnostic reference level (DRL). In this observational retrospective cohort study, dose data of 60 CT-guided liver biopsies between September 2016 and July 2017 were analysed. Radiation exposure was reported for volume-weighted CT dose index (CTDIvol), size-specific dose estimate (SSDE), dose-length product (DLP) and effective dose (ED). Radiation dose of CT-guided liver biopsy was (median (interquartile range)): CTDIvol9.91 mGy (8.33-11.45 mGy), SSDE 10.42 mGy (9.39-11.70 mGy), DLP 542 mGy cm (410-733 mGy cm), ED 8.52 mSv (7.17-13.25 mSv). Radiation exposure was significantly higher in biopsies of deep liver lesions compared to superficial lesions (DLP 679 ± 285 mGy cm vs. 497 ± 167 mGy cm,p= 0.0046). No significant dose differences were observed for differences in lesion or needle size. With helical CT spirals additional to the biopsy-guiding axial CT scans, radiation exposure was significantly increased: 797 ± 287 mGy cm vs. 495 ± 162 mGy cm,p< 0.0001. The local DRL is CTDIvol9.91 mGy, DLP 542 mGy cm. Radiation dose is significantly increased in biopsies of deeper liver lesions compared with superficial lesions. Interventions with additional biopsy-guiding CT spirals lead to higher radiation doses. This study provides a detailed analysis of local radiation doses for CT-guided liver biopsies and provides a benchmark for optimising radiation protection in interventional radiology.

Comparison of 18F-FDG PET/MRI and MRI for pre-therapeutic tumor staging of patients with primary cancer of the uterine cervix.

PURPOSE: The aim of the present study was to assess and compare the diagnostic performance of integrated PET/MRI and MRI alone for local tumor evaluation and whole-body tumor staging of primary cervical cancers. In addition, the corresponding impact on further patient management of the two imaging modalities was assessed. METHODS: A total of 53 consecutive patients with histopathological verification of a primary cervical cancer were prospectively enrolled for a whole-body 18F-FDG PET/MRI examination. Two experienced physicians analyzed the MRI data, in consensus, followed by a second reading session of the PET/MRI datasets. The readers were asked to perform a dedicated TNM staging in accordance with the 7th edition of the AJCC staging manual. Subsequently, the results of MRI and PET/MRI were discussed in a simulated interdisciplinary tumor board and therapeutic decisions based on both imaging modalities were recorded. Results from histopathology and cross-sectional imaging follow-up served as the reference standard. RESULTS: PET/MRI allowed for a correct determination of the T stage in 45/53 (85%) cases, while MRI alone enabled a correct identification of the tumor stage in 46/53 (87%) cases. In 24 of the 53 patients, lymph node metastases were present. For the detection of nodal-positive patients, sensitivity, specificity and accuracy of PET/MRI were 83%, 90% and 87%, respectively. The respective values for MRI alone were 71%, 83% and 77%. In addition, PET/MRI showed higher values for the detection of distant metastases than MRI alone (sensitivity: 87% vs. 67%, specificity: 92% vs. 90%, diagnostic accuracy: 91% vs. 83%). Among the patients with discrepant staging results in the two imaging modalities, PET/MRI enabled correct treatment recommendations for a higher number (n = 9) of patients than MRI alone (n = 3). CONCLUSION: The present results demonstrate the successful application of integrated PET/MRI imaging for whole-body tumor staging of cervical cancer patients, enabling improved treatment planning when compared to MRI alone.

Comparison of 18F-FDG PET/MRI and MRI alone for whole-body staging and potential impact on therapeutic management of women with suspected recurrent pelvic cancer: a follow-up study.

PURPOSE: To evaluate the diagnostic performance of 18F-FDG PET/MRI for whole-body staging and potential changes in therapeutic management of women with suspected recurrent pelvic cancer in comparison with MRI alone. METHODS: Seventy-one consecutive women (54 ± 13 years, range: 25-80 years) with suspected recurrence of cervical (32), ovarian (26), endometrial (7), vulvar (4), and vaginal (2) cancer underwent PET/MRI including a diagnostic contrast-enhanced MRI protocol. PET/MRI and MRI datasets were separately evaluated regarding lesion count, localization, categorization (benign/malignant), and diagnostic confidence (3-point scale; 1-3) by two physicians. The reference standard was based on histopathology results and follow-up imaging. Diagnostic accuracy and proportions of malignant and benign lesions rated correctly were retrospectively compared using McNemar's chi2 test. Differences in diagnostic confidence were assessed by Wilcoxon test. RESULTS: Fifty-five patients showed cancer recurrence. PET/MRI correctly identified more patients with cancer recurrence than MRI alone (100% vs. 83.6%, p < 0.01). In contrast to PET/MRI, MRI alone missed 4/15 patients with pelvic recurrence and miscategorized 8/40 patients with distant metastases as having local recurrence only. Based on the reference standard, 241 lesions were detected in the study cohort (181 malignant, 60 benign). While PET/MRI provided correct identification of 181/181 (100%) malignant lesions, MRI alone correctly identified 135/181 (74.6%) malignant lesions, which was significantly less compared to PET/MRI (p < 0.001). PET/MRI offered superior diagnostic accuracy (99.2% vs. 79.3%, p < 0.001) and diagnostic confidence in the categorization of malignant lesions compared with MRI alone (2.7 ± 0.5 vs. 2.4 ± 0.7, p < 0.001). CONCLUSION: PET/MRI demonstrates excellent diagnostic performance and outperforms MRI alone for whole-body staging of women with suspected recurrent pelvic cancer, indicating potential changes in therapy management based on evaluation of local recurrence and distant metastatic spread.

Can integrated 18F-FDG PET/MR replace sentinel lymph node resection in malignant melanoma?

PURPOSE: To compare the sensitivity and specificity of 18F-fluordesoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT), 18F-FDG PET/magnetic resonance (18F-FDG PET/MR) and 18F-FDG PET/MR including diffusion weighted imaging (DWI) in the detection of sentinel lymph node metastases in patients suffering from malignant melanoma. MATERIAL & METHODS: Fifty-two patients with malignant melanoma (female: n = 30, male: n = 22, mean age 50.5 ± 16.0 years, mean tumor thickness 2.28 ± 1.97 mm) who underwent 18F-FDG PET/CT and subsequent PET/MR & DWI for distant metastasis staging were included in this retrospective study. After hybrid imaging, lymphoscintigraphy including single photon emission computed tomography/CT (SPECT/CT) was performed to identify the sentinel lymph node prior to sentinel lymph node biopsy (SLNB). In a total of 87 sentinel lymph nodes in 64 lymph node basins visible on SPECT/CT, 17 lymph node metastases were detected by histopathology. In separate sessions PET/CT, PET/MR, and PET/MR & DWI were assessed for sentinel lymph node metastases by two independent readers. Discrepant results were resolved in a consensus reading. Sensitivities, specificities, positive predictive values and negative predictive values were calculated with histopathology following SPECT/CT guided SLNB as a reference standard. RESULTS: Compared with histopathology, lymph nodes were true positive in three cases, true negative in 65 cases, false positive in three cases and false negative in 14 cases in PET/CT. PET/MR was true positive in four cases, true negative in 63 cases, false positive in two cases and false negative in 13 cases. Hence, we observed a sensitivity, specificity, positive predictive value and negative predictive value of 17.7, 95.6, 50.0 and 82.3% for PET/CT and 23.5, 96.9, 66.7 and 82.3% for PET/MR. In DWI, 56 sentinel lymph node basins could be analyzed. Here, the additional analysis of DWI led to two additional false positive findings, while the number of true positive findings could not be increased. CONCLUSION: In conclusion, integrated 18F-FDG PET/MR does not reliably differentiate N-positive from N-negative melanoma patients. Additional DWI does not increase the sensitivity of 18F-FDG PET/MR. Hence, sentinel lymph node biopsy cannot be replaced by 18F-FDG-PE/MR or 18F-FDG-PET/CT.

Local and whole-body staging in patients with primary breast cancer: a comparison of one-step to two-step staging utilizing 18F-FDG-PET/MRI.

OBJECTIVES: The purpose of this study was to compare the diagnostic value of a one-step to a two-step staging algorithm utilizing 18F-FDG PET/MRI in breast cancer patients. METHODS: A total of 38 patients (37 females and one male, mean age 57 ± 10 years; range 31-78 years) with newly diagnosed, histopathologically proven breast cancer were prospectively enrolled in this trial. All PET/MRI examinations were assessed for local tumor burden and metastatic spread in two separate reading sessions: (1) One-step algorithm comprising supine whole-body 18F-FDG PET/MRI, and (2) Two-step algorithm comprising a dedicated prone 18F-FDG breast PET/MRI and supine whole-body 18F-FDG PET/MRI. RESULTS: On a patient based analysis the two-step algorithm correctly identified 37 out of 38 patients with breast carcinoma (97%), while five patients were missed by the one-step 18F-FDG PET/MRI algorithm (33/38; 87% correct identification). On a lesion-based analysis 56 breast cancer lesions were detected in the two-step algorithm and 44 breast cancer lesions could be correctly identified in the one-step 18F-FDG PET/MRI (79%), resulting in statistically significant differences between the two algorithms (p = 0.0015). For axillary lymph node evaluation sensitivity, specificity and accuracy was 93%, 95 and 94%, respectively. Furthermore, distant metastases could be detected in seven patients in both algorithms. CONCLUSION: The results demonstrate the necessity and superiority of a two-step 18F-FDG PET/MRI algorithm, comprising dedicated prone breast imaging and supine whole-body imaging, when compared to the one-step algorithm for local and whole-body staging in breast cancer patients.

Integrated 68Gallium Labelled Prostate-Specific Membrane Antigen-11 Positron Emission Tomography/Magnetic Resonance Imaging Enhances Discriminatory Power of Multi-Parametric Prostate Magnetic Resonance Imaging.

PURPOSE: To evaluate diagnostic accuracy of integrated 68Gallium labelled prostate-specific membrane antigen (68Ga-PSMA)-11 positron emission tomography (PET)/MRI in patients with primary prostate cancer (PCa) as compared to multi-parametric MRI. MATERIAL AND METHODS: A total of 22 patients with recently diagnosed primary PCa underwent clinically indicated 68Ga-PSMA-11 PET/CT for initial staging followed by integrated 68Ga-PSMA-11 PET/MRI. Images of multi-parametric magnetic resonance imaging (mpMRI), PET and PET/MRI were evaluated separately by applying Prostate Imaging Reporting and Data System (PIRADSv2) for mpMRI and a 5-point Likert scale for PET and PET/MRI. Results were compared with pathology reports of biopsy or resection. Statistical analyses including receiver operating characteristics analysis were performed to compare the diagnostic performance of mpMRI, PET and PET/MRI. RESULTS: PET and integrated PET/MRI demonstrated a higher diagnostic accuracy than mpMRI (area under the curve: mpMRI: 0.679, PET and PET/MRI: 0.951). The proportion of equivocal results (PIRADS 3 and Likert 3) was considerably higher in mpMRI than in PET and PET/MRI. In a notable proportion of equivocal PIRADS results, PET led to a correct shift towards higher suspicion of malignancy and enabled correct lesion classification. CONCLUSION: Integrated 68Ga-PSMA-11 PET/MRI demonstrates higher diagnostic accuracy than mpMRI and is particularly valuable in tumours with equivocal results from PIRADS classification.

18F-FDG PET/MRI in patients suffering from lymphoma: how much MRI information is really needed?

OBJECTIVES: To evaluate and compare the diagnostic potential of different reading protocols, entailing non-enhanced/contrast-enhanced and diffusion-weighted 18F-FDG PET/MR imaging for lesion detection and determination of the tumor stage in lymphoma patients. METHODS: A total of 101 18F-FDG PET/MRI datasets including a (1) transverse T2-w HASTE and 18F-FDG PET (PET/MRI1), (2) with an additional contrast enhanced VIBE (PET/MRI2), and (3) with additional diffusion-weighted imaging (PET/MRI3) were evaluated. Scans were performed for initial staging, restaging during treatment, or at the end of treatment and under surveillance with suspicion for tumor relapse. In all datasets lymphoma manifestations as well as tumor stage in analogy to the revised criteria of the Ann Arbor staging system were determined. Furthermore, potential changes in therapy compared to the reference standard were evaluated. Hitherto performed PET/CT and all available follow-up and prior examinations as well as histopathology served as reference standard. RESULTS: PET/MRI1 correctly identified 53/55 patients with active lymphoma and 190/205 lesions. Respective values were 55/55, 202/205 for PET/MRI2 and 55/55, 205/205 for PET/MRI3. PET/MRI1 determined correct tumor stage in 88 out of 101 examinations, and corresponding results for PET/MRI2 were 95 out of 101 and 96 out of 101 in PET/MRI3. Relating to the reference standard changes in treatment would occur in 11% based on PET/MRI1, in 6% based on PET/MRI2, and in 3% based on PET/MRI3. CONCLUSIONS: The additional application of contrast-enhanced and diffusion-weighted imaging to 18F-FDG PET/MRI resulted in higher diagnostic competence, particularly for initial staging and correct classification of the disease extent with potential impact on patient and therapy management.

Integrated 18F-FDG PET/MRI compared to MRI alone for identification of local recurrences of soft tissue sarcomas: a comparison trial.

PURPOSE: To assess and compare the diagnostic accuracy of PET/MRI and MRI alone for the detection of local recurrences of soft tissue sarcomas (STS) after initial surgical resection of the primary tumors. MATERIAL AND METHODS: A total of 41 patients with clinically suspected tumor relapse of STS underwent an 18F-FDG-PET/MRI examination for assessment of local recurrence. Two experienced physicians interpreted the MRI data and subsequently the PET/MRI datasets in two separate reading sessions and were instructed to identify potential local tumor recurrences. Additionally, the diagnostic confidence in each reading for the identification of malignant lesions was determined. A McNemar test was applied to test for differences of both ratings and a Wilcoxon signed-rank test was used to identify differences of the confidence levels. Histopathological verification and follow-up imaging were applied for standard of reference. RESULTS: Tumor relapse was present in 27/41 patients. Calculated sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy for the detection of local tumor recurrence was 82%, 86%, 92%, 71% and 83% for MRI, and 96%, 79%, 90%, 92% and 90% for PET/MRI (p > 0.05). Furthermore, PET/MRI showed significantly higher confidence levels (p < 0.05) for the determination of malignant lesions. CONCLUSION: Our results endorse 18F-FDG PET/MRI to be an excellent imaging method in the evaluation of recurrent STS after surgical excision, yielding superior tumor detection when compared to MRI alone.

Thoracic staging with 18F-FDG PET/MR in non-small cell lung cancer - does it change therapeutic decisions in comparison to 18F-FDG PET/CT?

OBJECTIVE: To investigate whether differences in thoracic tumour staging between 18F-FDG PET/CT and PET/MR imaging lead to different therapeutic decisions in Non-Small Cell Lung Cancer (NSCLC). MATERIAL AND METHODS: Seventy-seven NSCLC patients that underwent whole-body 18F-FDG PET/CT from the base of skull to the upper thighs and thoracic PET/MR were enrolled in this retrospective study. Thoracic PET/CT and PET/MR images were staged according to the 7th edition of the AJCC staging manual. Staging results of both modalities were discussed separately in a simulated interdisciplinary tumour board and therapeutic decisions based on both imaging modalities were recorded. Descriptive statistics were used to compare the results and reasons for changes in the therapeutic decision were investigated. RESULTS: Staging results differed in 35 % of patients (27 patients) between thoracic PET/CT and PET/MR. Differences were detected when assessing the T-stage in 18 % (n = 14), the N-stage in 23 % (n = 18), and the M-stage in 1 % (n = 1). However, patient therapy management was changed in only six patients (8 %). CONCLUSION: Despite the variability of thoracic 18F-FDG PET/CT and PET/MR in TNM-staging, both modalities lead to comparable therapeutic decisions in patients suffering from NSCLC. Hence, 18F-FDG PET/MR can be considered an possible alternative to 18F-FDG PET/CT for clinical NSCLC staging. KEY POINTS: • PET/CT and PET/MR provide comparable results in early stages in NSCLC • Clinical impact of different staging results has not been investigated • PET/CT and PET/MR lead to comparable therapeutic decisions • PET/MR can be considered an alternative to PET/CT for NSCLC staging.

Diagnostic impact of integrated 18F-FDG PET/MRI in cerebral staging of patients with non-small cell lung cancer.

Background Integrated positron emission tomography/magnetic resonance imaging (PET/MRI) systems are increasingly being available and used for staging examinations. Brain metastases (BM) are frequent in patients with non-small cell lung cancer (NSCLC) and decisive for treatment strategy. Purpose To assess the diagnostic value of integrated 18F-2-fluoro-2-deoxy-D glucose (18F-FDG) PET/MRI in initial staging in patients with NSCLC for BM in comparison to MRI alone. Material and Methods Eighty-three patients were prospectively enrolled for an integrated 18F-FDG PET/MRI examination. The 3 T MRI protocol included a fluid-attenuated inversion-recovery sequence (FLAIR) and a contrast-enhanced three-dimensional magnetization prepared rapid acquisition GRE sequence (MPRAGE). Two neuroradiologists evaluated the datasets in consensus regarding: (i) present lesions; (ii) size of lesions; and (iii) number of lesions detected in MRI alone, compared to the PET component when reading the 18F-FDG PET/MRI. Results Based on MRI alone, BM were detected in 15 out of the 83 patients, comprising a total of 39 metastases. Based on PET alone, six patients out of the 83 patients were rated positive for metastatic disease, revealing a total of 15 metastases. PET detected no additional BM. The size of the BM correlated positively with sensitivity of detection in PET. Conclusion The sensitivity of PET in detection of BM depends on their size. 18F-FDG PET/MRI does not lead to an improvement in diagnostic accuracy in cerebral staging of NSCLC patients, as MRI alone remains the gold standard.

[(18)F]FDG PET/MRI vs. PET/CT for whole-body staging in patients with recurrent malignancies of the female pelvis: initial results.

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.

Integrated PET/MRI for whole-body staging of patients with primary cervical cancer: preliminary results.

PURPOSE: To assess the diagnostic value of integrated PET/MRI for whole-body staging of cervical cancer patients, as well as to investigate a potential association between PET/MRI derived functional parameters and prognostic factors of cervical cancer. METHODS: The present study was approved by the local institutional review board. Twenty-seven patients with histopathologically confirmed cervical cancer were prospectively enrolled in our study. All patients underwent a whole-body PET/MRI examination after written informed consent was obtained. Two radiologists separately evaluated the PET/MRI data sets regarding the determination of local tumor extent of primary cervical cancer lesions, as well as detection of nodal and distant metastases. Furthermore, SUV and ADC values of primary tumor lesions were analyzed and correlated with dedicated prognostic factors of cervical cancer. Results based on histopathology and cross-sectional imaging follow-up served as the reference standard. RESULTS: PET/MRI enabled the detection of all 27 primary tumor lesions of the uterine cervix and allowed for the correct determination of the T-stage in 23 (85 %) out of the 27 patients. Furthermore, the calculated sensitivity, specificity and diagnostic accuracy for the detection of nodal positive patients (n = 11) were 91 %, 94 % and 93 %, respectively. PET/MRI correctly identified regional metastatic disease (N1-stage) in 8/10 (80 %) patients and non-regional lymph node metastases in 5/5 (100 %) patients. In addition, quantitative analysis of PET and MRI derived functional parameters (SUV; ADC values) revealed a significant correlation with pathological grade and tumor size (p < 0.05). CONCLUSIONS: The present study demonstrates the high potential of integrated PET/MRI for the assessment of primary tumor and the detection of lymph node metastases in patients with cervical cancer. Providing additional prognostic information, PET/MRI may serve as a valuable diagnostic tool for cervical cancer patients in a pretreatment setting.

Thoracic staging of non-small-cell lung cancer using integrated (18)F-FDG PET/MR imaging: diagnostic value of different MR sequences.

PURPOSE: To compare the accuracy of different MR sequences in simultaneous PET/MR imaging for T staging in non-small-cell lung cancer in relation to histopathology. METHODS: The study included 28 patients who underwent dedicated thoracic PET/MR imaging before tumour resection. Local tumour staging was performed separately by three readers with each of the following MR sequences together with PET: transverse T2 BLADE, transverse non-enhanced and contrast-enhanced T1 FLASH, T1 3D Dixon VIBE in transverse and coronal orientation, coronal T2 HASTE, and coronal TrueFISP. The staging results were compared with histopathology after resection as the reference standard. Differences in the accuracy of T staging among the MR sequences were evaluated using McNemar's test. Due to multiple testing, Bonferroni correction was applied to prevent accumulation of α errors; p < 0.0024 was considered statistically significant. RESULTS: Compared with histopathology, T-staging accuracy was 69% with T2 BLADE, 68% with T2 HASTE, 59% with contrast-enhanced T1 FLASH, 57% with TrueFISP, 50 % with non-enhanced T1 FLASH, and 45% and 48% with T1 3D Dixon VIBE in transverse and coronal orientation, respectively. Staging accuracy with T2 BLADE was significantly higher than with non-enhanced T1 FLASH and with T1 3D Dixon VIBE in transverse and coronal orientations (p < 0.0024). T2 HASTE had a significantly higher T-staging accuracy than transverse T1 3D-Dixon-VIBE (p < 0.0024). CONCLUSION: Transverse T2 BLADE images provide the highest accuracy for local tumour staging and should therefore be included in dedicated thoracic PET/MR protocols. As T1 3D Dixon VIBE images acquired for attenuation correction performed significantly worse, this sequence cannot be considered sufficiently accurate for local tumour staging in the thorax.

Whole-body [¹8F]FDG PET/MRI vs. PET/CT in the assessment of bone lesions in oncological patients: initial results.

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.

Radiomics Analysis of Multiparametric PET/MRI for N- and M-Staging in Patients with Primary Cervical Cancer.

PURPOSE: The aim of this study was to investigate the potential of multiparametric 18F-FDG PET/MR imaging as a platform for radiomics analysis and machine learning algorithms based on primary cervical cancers to predict N- and M-stage in patients. MATERIALS AND METHODS: A total of 30 patients with histopathological confirmation of primary and untreated cervical cancer were prospectively enrolled for a multiparametric 18F-FDG PET/MR examination, comprising a dedicated protocol for imaging of the female pelvis. The primary tumor in the uterine cervix was manually segmented on post-contrast T1-weighted images. Quantitative features were extracted from the segmented tumors using the Radiomic Image Processing Toolbox for the R software environment for statistical computing and graphics. 45 different image features were calculated from non-enhanced as well as post-contrast T1-weighted TSE images, T2-weighted TSE images, the ADC map, the parametric Ktrans, Kep, Ve and iAUC maps and PET images, respectively. Statistical analysis and modeling was performed using Python 3.5 and the scikit-learn software machine learning library for the Python programming language. RESULTS: Prediction of M-stage was superior when compared to N-stage. Prediction of M-stage using SVM with SVM-RFE as feature selection obtained the highest performance providing sensitivity of 91 % and specificity of 92 %. Using receiver operating characteristic (ROC) analysis of the pooled predictions, the area under the curve (AUC) was 0.97. Prediction of N-stage using RBF-SVM with MIFS as feature selection reached sensitivity of 83 %, specificity of 67 % and an AUC of 0.82. CONCLUSION: M- and N-stage can be predicted based on isolated radiomics analyses of the primary tumor in cervical cancers, thus serving as a template for noninvasive tumor phenotyping and patient stratification using high-dimensional feature vectors extracted from multiparametric PET/MRI data. KEY POINTS: · Radiomics analysis based on multiparametric PET/MRI enables prediction of the metastatic status of cervical cancers. · Prediction of M-stage is superior to N-stage. · Multiparametric PET/MRI displays a valuable platform for radiomics analyses .

Expression of tumor-promoting Cyr61 is regulated by hTRA2-ß1 and acidosis.

The matricellular protein Cysteine rich 61 (Cyr61) displays a remarkable diversity of multiple cellular functions involved in significant physiologic and pathologic processes. Cyr61 is known as an important player in tumor progression, promoting neovascularization and metastasis. Our prior investigations elucidated an oxygen-dependent Cyr61 alternative splicing process characterized by retention of its intron 3, regulating its biological function in a hypoxia-driven on/off switch mechanism. In this work, we identified extracellular acidosis as a potent inducer for altered Cyr61 alternative splicing pattern regulating Cyr61 expression. Intriguingly, splicing factor hTRA2-beta1 displayed an opposite effect on Cyr61 expression. Nuclear hTRA2-beta1 protein expression was found markedly reduced under acidic conditions. In keeping with these conclusions, we show that hTRA2-beta1 can specifically bind a 'GAAG' motif in Cyr61 exon 3 RNA, that the splicing factor displays acidosis-dependent protein localization in cellular compartments, and shRNA-mediated hTRA2-beta1 knock-down triggers the same effects on Cyr61 alternative splicing like acidosis or hypoxia. Our findings strongly support the hypothesis of a specific regulation of Cyr61 expression by hTRA2-beta1.

Adipopenia in body composition analysis: a promising imaging biomarker and potential predictive factor for patients undergoing transjugular intrahepatic portosystemic shunt placement.

OBJECTIVE: Body tissue composition plays a crucial role in the multisystemic processes of advanced liver disease and has been shown to be influenced by transjugular intrahepatic portosystemic shunt (TIPS). A differentiated analysis of the various tissue compartments has not been performed until now. The purpose of this study was to evaluate the value of imaging biomarkers derived from automated body composition analysis (BCA) to predict clinical and functional outcome. METHODS: A retrospective analysis of 56 patients undergoing TIPS procedure between 2013 and 2021 was performed. BCA on the base of pre-interventional CT examination was used to determine quantitative data as well as ratios of bone, muscle and fat masses. Furthermore, a BCA-derived sarcopenia marker was investigated. Regarding potential correlations between BCA imaging biomarkers and the occurrence of hepatic encephalopathy (HE) as well as 1-year survival, an exploratory analysis was conducted. RESULTS: No BCA imaging biomarker was associated with the occurrence of HE after TIPS placement. However, there were significant differences in alive and deceased patients regarding the BCA-derived sarcopenia marker (alive: 1.60, deceased: 1.83, p = 0.046), ratios of intra- and intermuscular fat/skeletal volume (alive: 0.53, deceased: 0.31, p = 0.015) and intra- and intermuscular fat/muscle volume (alive: 0.21, deceased: 0.14, p = 0.031). CONCLUSION: A lower amount of intra- and intermuscular adipose tissue might have protective effects regarding liver derived complications and survival. ADVANCES IN KNOWLEDGE: Precise characterization of body tissue components with automated BCA might provide prognostic information in patients with advanced liver disease undergoing TIPS procedure.

Correlation of the apparent diffusion coefficient with the standardized uptake value in meningioma of the skull plane using [68]Ga-DOTATOC PET/MRI.

PURPOSE: To evaluate a correlation between an MRI-specific marker for cellular density [apparent diffusion coefficient (ADC)] and the expression of Somatostatin Receptors (SSTR) in patients with meningioma of the skull plane and orbital space. METHODS: 68 Ga-DOTATOC PET/MR imaging was performed in 60 Patients with suspected or diagnosed meningiomas of the skull base and eye socket. Analysis of ADC values succeeded in 32 patients. ADC values (ADC mean and ADC min ) were analyzed using a polygonal region of interest. Tracer-uptake of target lesions was assessed according to corresponding maximal (SUV max ) and mean (SUV mean ) values. Correlations between assessed parameters were evaluated using the Pearson correlation coefficient. RESULTS: One out of 32 patients (3%) was diagnosed with lymphoma by histopathological examination and therefore excluded from further analysis. Median ADC mean amounted to 822 × 10 -5  mm²/s -1 (95% CI: 570-1497) and median ADC min was 493 × 10 -5 mm 2 /s -1 (95% CI: 162-783). There were no significant correlations between SUV max and ADC min (r = 0.60; P  = 0.76) or ADC mean (r = -0.52; P  = 0.79), respectively. However, Pearson's test showed a weak, inverse but insignificant correlation between ADC mean and SUV mean (r = -0.33; P  = 0.07). CONCLUSION: The presented data displays no relevant correlations between increased SSTR expression and cellularity in patients with meningioma of the skull base. SSTR-PET and DWI thus may offer complementary information on tumor characteristics of meningioma.

Evaluation of [68Ga]-DOTATOC PET/MRI in Patients with Meningioma of the Subcranial and Intraorbital Space.

Meningiomas are known to express somatostatin receptor (SSTR) type 2 to a high degree. Therefore, radiolabeled somatostatin analogs, such as DOTATOC, have been introduced for PET imaging of meningiomas. However, the benefit of hybrid SSTR PET/MRI is still debated. Here, we report our experience with [68Ga]-DOTATOC PET/MRI. Methods: PET/MRI was performed in 60 patients with suspected or diagnosed meningiomas of the skull plane and eye socket. Acquired datasets were reported by 2 independent readers regarding local tumor extent and signal characteristics. Histopathologic results and follow-up imaging served as the reference standard. SUVs of target lesions were analyzed according to the corresponding maximal tracer uptake. The diagnostic accuracy of PET/MRI and conventional MRI was determined independently and compared with the reference standard. Results: In total, 60 target lesions were identified, with 54 considered to be meningiomas according to the reference standard. Sensitivity and specificity of PET/MRI versus MRI alone were 95% versus 96% and 75% versus 66%, respectively. The McNemar test was not able to distinguish any differences between PET/MRI and the reference standard or MRI and the reference standard. No differences were found between the 2 modalities with respect to local infiltration. Conclusion: SSTR PET/MRI and MRI yielded similar accuracy for the detection of meningiomas of the skull base and intraorbital space. Here, sequential low-dose SSTR PET/CT might be helpful for the planning of radioligand therapy or radiotherapy.

Streamlining Patient Management of Suspected COVID-19 Patients in the Emergency Department: Incorporation of Pulmonary CT Angiography into the Triaging Algorithm.

Purpose: To evaluate the use of pulmonary computed tomography (CT) angiography during initial admission at an emergency department (ED), to identify COVID-19 patients with accompanying pulmonary embolism (PE) and its impact on clinical management. Methods: We performed a retrospective analysis of COVID-19 patients that underwent pulmonary CT angiography at the ED. CT scans were evaluated for the presence and extent of PE and for imaging changes suspicious of COVID-19. Patients were subdivided into two groups: (1) Group A consisted of patients with proven COVID-19 based on real-time polymerase chain reaction (RT-PCR), and (2) Group B of patients suspected for COVID-19, comprising patients positive on RT-PCR and/or COVID-19-suspicious CT findings. To assess the differences between patients with and without pulmonary embolism, Fisher's exact test was used. Results: A total of 308 patients were admitted to the ED for diagnostic work-up of dyspnea and suspected COVID-19, and 95 patients underwent pulmonary CT angiography. PE was detected in 13.6% (3/22) of patients in Group A and 20.7% (6/29) in Group B. No significant differences were observed between patients with and without PE concerning hospitalization (Group B: 100% (6/6) vs. 91.3% (21/23)), the necessity of oxygen therapy (Group B: 66% (4/6) vs. 43.5% (10/23)), and death (Group B: 33% (2/6) vs. 4.3% (1/23) p > 0.05, respectively). Conclusions: In 20.7% of COVID-19 patients, PE was detected upon admission to the ED. Although the incorporation of early pulmonary CT angiography in patients suspicious of COVID-19 may be beneficial to identify concomitant PE, further studies are necessary to corroborate these findings.