[Consensus recommendations on regional interdisciplinary standardization of MRI diagnostics for multiple sclerosis in the metropolitan area of Essen]. / Konsensusempfehlungen zur regionalen fächerübergreifenden Standardisierung der MRT-Diagnostik bei Multipler Sklerose im Großraum Essen.

Magnetic resonance imaging (MRI) is of exceptional importance in the diagnostics and monitoring of multiple sclerosis (MS); however, a close interdisciplinary cooperation between neurologists in private practice, (neuro)radiological practices, hospitals or specialized MS centers is only rarely established. In particular, there is a lack of standardized MRI protocols for image acquisition as well as established quality parameters, which guarantee the comparability of MRI records; however, this is a fundamental prerequisite for an effective application of MRI in the treatment of MS patients, e.g., for making the diagnosis or treatment monitoring. To address these challenges a group of neurologists and (neuro)radiologists developed a consensus proposal for standardization of image acquisition, interpretation and transmission of results and for improvement in interdisciplinary cooperation. This pilot project in the metropolitan area of Essen used a modified Delphi process and was based on the most up to date scientific knowledge. The recommendation takes the medical, economic, temporal and practical aspects of MRI in MS into consideration. The model of interdisciplinary cooperation between radiologists and neurologists with the aim of a regional standardization of MRI could serve as an example for other regions of Germany in order to optimize MRI for MS.

Incidental 18F-FDG uptake in the colon: value of contrast-enhanced CT correlation with colonoscopic findings.

OBJECTIVES: To evaluate the impact of morphological information derived from contrast-enhanced CT in the characterization of incidental focal colonic uptake in 18F-FDG PET/CT examinations. METHODS: A total of 125 patients (female: n = 53, male: n = 72) that underwent colonoscopy secondary to contrast-enhanced, full-dose PET/CT without special bowel preparation were included in this retrospective study. PET/CT examinations were assessed for focal colonic tracer uptake in comparison with the background. Focal tracer uptake was correlated with morphological changes of the colonic wall in the contrast-enhanced CT images. Colonoscopy reports were evaluated for benign, inflammatory, polypoid, precancerous, and cancerous lesions verified by histopathology, serving as a reference standard. Sensitivity, specificity, PPV, NPV, and accuracy for detection of therapeutic relevant findings were calculated for (a) sole focal tracer uptake and (b) focal tracer uptake with correlating CT findings in contrast-enhanced CT. RESULTS: In 38.4% (48/125) of the patients, a focal 18F-FDG uptake was observed within 67 lesions. Malignant lesions were endoscopically and histopathologically diagnosed in eleven patients, and nine of these were detected by focal 18F-FDG uptake. A total of 34 lesions with impact on short- or long-term patient management (either being pre- or malignant) were detected. Sensitivity, Specificity, PPV, NPV, and accuracy for sole 18F-FDG uptake for this combined group were 54%, 69%, 29%, 85%, and 65%. Corresponding results for focal 18F-FDG uptake with correlating CT findings were 38%, 90%, 50%, 86%, and 80%. This resulted in a statistically significant difference for diagnostic accuracy (p = 0.0001) CONCLUSION: By analyzing additional morphological changes in contrast-enhanced CT imaging, the specificity of focal colonic 18F-FDG uptake for precancerous and cancerous lesions can be increased but leads to a considerate loss of sensitivity. Therefore, every focal colonic uptake should be followed up by colonoscopy.

Prospective comparison of 18F-FDG PET/MRI and 18F-FDG PET/CT for thoracic staging of non-small cell lung cancer.

OBJECTIVES: To compare the diagnostic performance of 18F-FDG PET/MRI and 18F-FDG PET/CT for primary and locoregional lymph node staging in non-small cell lung cancer (NSCLC). METHODS: In this prospective study, a total of 84 patients (51 men, 33 women, mean age 62.5 ± 9.1 years) with histopathologically confirmed NSCLC underwent 18F-FDG PET/CT followed by 18F-FDG PET/MRI in a single injection protocol. Two readers independently assessed T and N staging in separate sessions according to the seventh edition of the American Joint Committee on Cancer staging manual for 18F-FDG PET/CT and 18F-FDG PET/MRI, respectively. Histopathology as a reference standard was available for N staging in all 84 patients and for T staging in 39 patients. Differences in staging accuracy were assessed by McNemars chi2 test. The maximum standardized uptake value (SUVmax) and longitudinal diameters of primary tumors were correlated using Pearson's coefficients. RESULTS: T stage was categorized concordantly in 18F-FDG PET/MRI and 18F-FDG PET/CT in 38 of 39 (97.4%) patients. Herein, 18F-FDG PET/CT and 18F-FDG PET/MRI correctly determined the T stage in 92.3 and 89.7% of patients, respectively. N stage was categorized concordantly in 83 of 84 patients (98.8%). 18F-FDG PET/CT correctly determined the N stage in 78 of 84 patients (92.9%), while 18F-FDG PET/MRI correctly determined the N stage in 77 of 84 patients (91.7%). Differences between 18F-FDG PET/CT and 18F-FDG PET/MRI in T and N staging accuracy were not statistically significant (p > 0.5, each). Tumor size and SUVmax measurements derived from both imaging modalities exhibited excellent correlation (r = 0.963 and r = 0.901, respectively). CONCLUSION: 18F-FDG PET/MRI and 18F-FDG PET/CT show an equivalently high diagnostic performance for T and N staging in patients suffering from NSCLC.

Prospective comparison of whole-body MRI and 68Ga-PSMA PET/CT for the detection of biochemical recurrence of prostate cancer after radical prostatectomy.

PURPOSE: To assess whole-body magnetic resonance imaging (wb-MRI) for detection of biochemical recurrence in comparison to 68Ga-prostate-specific membrane antigen positron emission tomography/computed tomography (68Ga-PSMA PET/CT) in prostate cancer (Pca) patients after radical prostatectomy. METHODS: This was a prospective trial including 28 consecutive patients (mean age 65.3 ± 9.0 years) with newly documented biochemical recurrence of Pca (mean prostate-specific antigen, PSA, 2.09 ± 1.95 ng/ml) following radical prostatectomy. All patients underwent both wb-MRI including a dedicated pelvic imaging protocol and PET/CT with 166 ± 35 MBq 68Ga-PSMA within a time window of 11 ± 10 days. PET/CT and MRI datasets were separately evaluated regarding Pca lesion count, type, localization and diagnostic confidence (three-point Likert scale, 1-3) by two nuclear medicine specialists and two radiologists, respectively. The reference standard was based on histopathological results, PSA levels following targeted salvage irradiation and follow-up imaging. Lesion-based and patient-based detection rates were compared using the chi-squared test. Differences in diagnostic confidence were assessed using the Welch test. RESULTS: A total of 56 Pca lesions were detected in 20 of the 28 patients. 68Ga-PSMA PET/CT detected 56 of 56 lesions (100%) in 20 patients (71.4%), while wb-MRI detected 13 lesions (23.2%) in 11 patients (39.3%). The higher detection rate with 68Ga-PSMA PET/CT was statistically significant on both a per-lesion basis (p < 0.001) and a per-patient basis (p = 0.0167). In 8 patients (28.6%) no relapse was detectable by either modality. All lesions detected by wb-MRI were also detected by 68Ga-PSMA PET/CT. Additionally, 68Ga-PSMA PET/CT provided superior diagnostic confidence in identifying Pca lesions (2.7 ± 0.7 vs. 2.3 ± 0.6, p = 0.044). CONCLUSION: 68Ga-PSMA PET/CT significantly out-performed wb-MRI in the detection of biochemical recurrence in Pca patients after radical prostatectomy.

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.

Feasibility of FDG-PET in myocarditis: Comparison to CMR using integrated PET/MRI.

OBJECTIVE: Besides cardiac sarcoidosis, FDG-PET is rarely used in the diagnosis of myocardial inflammation, while cardiac MRI (CMR) is the actual imaging reference for the workup of myocarditis. Using integrated PET/MRI in patients with suspected myocarditis, we prospectively compared FDG-PET to CMR and the feasibility of integrated FDG-PET/MRI in myocarditis. METHODS: A total of 65 consecutive patients with suspected myocarditis were prospectively assessed using integrated cardiac FDG-PET/MRI. Studies comprised T2-weighted imaging, late gadolinium enhancement (LGE), and simultaneous PET acquisition. Physiological glucose uptake in the myocardium was suppressed using dietary preparation. RESULTS: FDG-PET/MRI was successful in 55 of 65 enrolled patients: two patients were excluded due to claustrophobia and eight patients due to failed inhibition of myocardial glucose uptake. Compared with CMR (LGE and/or T2), sensitivity and specificity of PET was 74% and 97%. Overall spatial agreement between PET and CMR was κ = 0.73. Spatial agreement between PET and T2 (κ = 0.75) was higher than agreement between PET and LGE (κ = 0.64) as well as between LGE and T2 (κ = 0.56). CONCLUSION: In patients with suspected myocarditis, FDG-PET is in good agreement with CMR findings.

Osteochondritis dissecans shows a severe course and poor outcome in patients with juvenile idiopathic arthritis: a matched pair study of 22 cases.

Juvenile osteochondritis dissecans (JOCD) and juvenile idiopathic arthritis (JIA) are both common diseases which may affect joints and bony structures in pediatric patients. In some cases, JOCD and JIA occur at the same time. In this study, the course of JOCD in patients with JIA was therefore evaluated to provide possible recommendations for further treatment opportunities and control examinations. From 06/2012 to 03/2018 55 children with JOCD with or without JIA were examined. Inclusion criteria were: (1) age ≤ 16 years, (2) diagnosis of a JOCD with or without JIA and (3) two routine MRI controls. The JOCD evaluation based on the classification according to Bruns and the measurement of the largest extent via MRI. 18 of these 55 children met our criteria: 11 JOCD findings of 7 patients with JIA (group A) were matched according to age and localization of JOCD to 11 patients without JIA (group B). Mean age of disease onset of JIA was 8.2 years (oligo JIA) and of JOCD 11.6 years. The mean time follow-up was 17.7 months. At all observation time points more JOCD findings (with stage III° and IV°, respectively) along with a significant deterioration was seen in group A compared to group B. The comparison of the last MRI control between group A and group B shows a significant smaller defect size (decrease of 54.5%, p = 0.028) in group B (97.9 ± 48.9 mm2) as in group A (185.1 ± 102.9 mm2). In comparison of first (169.7 ± 84.2 mm2) and last MRI (97.9 ± 48.9 mm2) a significant decrease in lesion size of JOCD in group B was seen (decrease of 58.4%, p = 0.048). Patients with JIA show a more progressive and severe course of JOCD. Therefore, we recommend (1) the early use of MRI in patients with JIA and persistent joint pain to detect potential JOCD and (2) in presence of JIA and JOCD regular MRI follow-up controls to identify deteriorating JOCD findings and prevent early joint destruction in pediatric patients.

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.

Evaluation of 68Ga-DOTATOC PET/MRI for whole-body staging of neuroendocrine tumours in comparison with 68Ga-DOTATOC PET/CT.

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.

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.

Metal artifact reduction (MAR) based on two-compartment physical modeling: evaluation in patients with hip implants.

BACKGROUND: Artifacts from metallic implants can hinder image interpretation in computed tomography (CT). Image quality can be improved using metal artifact reduction (MAR) techniques. PURPOSE: To evaluate the impact of a MAR algorithm on image quality of CT examinations in comparison to filtered back projection (FBP) in patients with hip prostheses. MATERIAL AND METHODS: Twenty-two patients with 25 hip prostheses who underwent clinical abdominopelvic CT on a 64-row CT were included in this retrospective study. Axial images were reconstructed with FBP and five increasing MAR levels (M30-34). Objective artifact strength (OAS) (SIart-SInorm) was assessed by region of interest (ROI) measurements in position of the strongest artifact (SIart) and in an osseous structure without artifact (SInorm) (in Hounsfield units [HU]). Two independent readers evaluated subjective image quality regarding metallic hardware, delineation of bone, adjacent muscle, and pelvic organs on a 5-point scale (1, non-diagnostic; 5, excellent image quality). Artifacts in the near field, far field, and newly induced artifacts due to the MAR technique were analyzed. RESULTS: OAS values were: M34: 243.8 ± 155.4 HU; M33: 294.3 ± 197.8 HU; M32: 340.5 ± 210.1 HU; M31: 393.6 ± 225.2 HU; M30: 446.8 ± 224.2 HU and FBP: 528.9 ± 227.7 HU. OAS values were significantly lower for M32-34 compared to FBP (P < 0.01). For overall subjective image quality, results were: FBP, 2.0 ± 0.2; M30, 2.3 ± 0.8; M31, 2.6 ± 0.5; M32, 3.0 ± 0.6; M33, 3.5 ± 0.6; and M34, 3.8 ± 0.4 (P < 0.001 for M30-M34 vs. FBP, respectively). Increasing MAR levels resulted in new artifacts in 17% of reconstructions. CONCLUSION: The investigated MAR algorithm led to a significant reduction of artifacts from metallic hip implants. The highest MAR level provided the least severe artifacts and the best overall image quality.

Contrast-Enhanced Computed Tomography in Intensive Care Unit Patients With Acute Clinical Deterioration: Impact of Hyperattenuating Adrenal Glands.

PURPOSE: The study sought to assess the frequency and prognostic value of hyperattenuating adrenal glands on contrast-enhanced computed tomography (CT) scans of surgical intensive care unit (ICU) patients with acute clinical deterioration. METHODS: Eighty-eight consecutive ICU patients (63.2 ± 14.5 years of age) were included in this retrospective analysis. All patients underwent biphasic contrast-enhanced CT due to an acute clinical deterioration. Hyperattenuation of the adrenal glands was assessed subjectively and objectively. Subjective presence or absence of hyperattenuating adrenal glands was assessed by 2 blinded radiologists (J.B. and R.S.L.) in consensus. Hounsfield units (HU) were measured in the adrenal glands and in the inferior vena cava. Objective hyperattenuation was defined as HU (adrenal glands) > HU (inferior vena cava) with a 15-HU threshold. Death within 14 days following CT was set as endpoint and acquired from electronic patient data. RESULTS: Thirty-eight patients (43.2%, Group Asubj) exhibited hyperattenuation of the adrenal glands, whereas 50 patients (56.8%, Group Bsubj) did not. Concerning the objective analysis, 31 patients (35.2%, Group Aobj) exhibited hyperdense adrenal glands, whereas 53 patients (64.8%, Group Bobj) did not. Overall 27 of 88 patients (30.6%) died within 14 days following the CT examination. Lethal outcome was significantly more frequent among patients in Group Asubj and Aobj (19 of 38 patients [50.0%] and 15 of 31 patients [48.4%]) as compared with patients in Group Bsubj (8 of 50 patients [16.0%]) and Group Bobj (12 of 57 patients [21.1%]; P < .05). Subjective and objective analysis correlated significantly (P < .05). CONCLUSIONS: Hyperattenuation of adrenal glands on contrast-enhanced CT of ICU patients with acute clinical deterioration is associated with a high mortality and might serve as a prognostic marker for patients' outcome.

Locoregional tumour evaluation of squamous cell carcinoma in the head and neck area: a comparison between MRI, PET/CT and integrated PET/MRI.

PURPOSE: To evaluate the accuracy of integrated (18)F-FDG PET/MR imaging for locoregional tumour evaluation compared to (18)F-FDG PET/CT and MR imaging in initial tumour and recurrence diagnosis in histopathologically confirmed head and neck squamous cell carcinoma (HNSCC). METHODS: (18)F-FDG PET/CT and integrated (18)F-FDG PET/MR imaging were performed for initial tumour staging or recurrence diagnosis in 25 patients with HNSCC. MR, fused (18)F-FDG PET/CT and fused (18)F-FDG PET/MR images were analysed by two independent readers in separate sessions in random order. In initial tumour staging, T and N staging was performed while individual lesions were analysed in patients with suspected cancer recurrence. In T and N staging, histopathological results after tumour resection served as the reference standard while histopathological sampling as well as cross-sectional and clinical follow-up were accepted in cancer recurrence diagnosis. The diagnostic accuracy of each modality was calculated separately for T and N staging as well as for tumour recurrence, and compared using McNemar's test. Values of p <0.017 were considered statistically significant after Bonferroni correction. RESULTS: In 12 patients undergoing (18)F-FDG PET/CT and (18)F-FDG PET/MR for initial tumour staging, T staging was accurate in 50 % with MRI, in 59 % with PET/CT and in 75 % with PET/MR while N staging was accurate in 75 % with MRI, in 77 % with PET/CT and in 71 % with PET/MR in relation to the reference standard. No significant differences were observed in T and N staging among the three modalities (p > 0.017). In 13 patients undergoing hybrid imaging for cancer recurrence diagnosis, diagnostic accuracy was 57 % with MRI and in 72 % with (18)F-FDG PET/CT and (18)F-FDG PET/MR, respectively. Again, no significant differences were found among the three modalities (p > 0.017). CONCLUSION: In this initial study, no significant differences were found among (18)F-FDG PET/MR, (18)F-FDG PET/CT and MRI in local tumour staging and cancer recurrence diagnosis.

Potential influence of Gadolinium contrast on image segmentation in MR-based attenuation correction with Dixon sequences in whole-body 18F-FDG PET/MR.

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.

Integrated FDG PET/MR Imaging for the Assessment of Myocardial Salvage in Reperfused Acute Myocardial Infarction.

PURPOSE: To compare the size of the area with reduced myocardial fluorodeoxygluose (FDG) uptake with the endocardial surface area (ESA) method as a marker for the area at risk in patients with reperfused acute myocardial infarction. MATERIALS AND METHODS: The study was approved by the local institutional review board. All patients gave written informed consent prior to their examination. Twenty-five patients (mean age ± standard deviation, 54 years ± 14) underwent prospective cardiac positron emission tomography/magnetic resonance imaging after acute coronary occlusion and interventional reperfusion. On late gadolinium contrast enhancement images, the size of infarction and the area at risk, as determined with ESA, were assessed and compared with the area of reduced FDG uptake. Statistical analysis comprised paired t tests and Mann-Whitney U tests, as well as Pearson r and Spearman ρ for correlations. RESULTS: In patients with infarcted myocardium and reduced FDG uptake (n = 18), a good correlation between the area of reduced FDG uptake and the area at risk according to ESA was observed (r = .70, P = .001). The area of reduced FDG uptake (31% ± 11 of left ventricular myocardial mass) was larger than the size of the infarct (10% ± 10, P < .0001) and the area at risk according to ESA (17% ± 13, P < .0001). In six patients, no late contrast enhancement was seen, whereas all patients had an area of reduced FDG uptake (29% ± 8) in the perfusion territory of the culprit artery. CONCLUSION: In patients with reperfused acute myocardial infarction, the area of reduced FDG uptake correlates with the area at risk as determined with the ESA method and is localized in the perfusion territory of the culprit artery in the absence of necrosis, although the area of reduced FDG uptake largely overestimates the size of the infarct and the ESA-based area at risk.

Diagnostic accuracy of whole-body PET/MRI and whole-body PET/CT for TNM staging in oncology.

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.

[(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.