[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.

Structured Reporting of Solid and Cystic Pancreatic Lesions in CT and MRI: Consensus-Based Structured Report Templates of the German Society of Radiology (DRG). / Strukturierte Befundung von soliden und zystischen Pankreasläsionen im CT und MRT: Konsensus-basierte Befundvorlagen der Deutschen Röntgengesellschaft (DRG).

BACKGROUND: Radiological reports of pancreatic lesions are currently widely formulated as free texts. However, for optimal characterization, staging and operation planning, a wide range of information is required but is sometimes not captured comprehensively. Structured reporting offers the potential for improvement in terms of completeness, reproducibility and clarity of interdisciplinary communication. METHOD: Interdisciplinary consensus finding of structured report templates for solid and cystic pancreatic tumors in computed tomography (CT) and magnetic resonance imaging (MRI) with representatives of the German Society of Radiology (DRG), German Society for General and Visceral Surgery (DGAV), working group Oncological Imaging (ABO) of the German Cancer Society (DKG) and other radiologists, oncologists and surgeons. RESULTS: Among experts in the field of pancreatic imaging, oncology and pancreatic surgery, as well as in a public online survey, structured report templates were developed by consensus. These templates are available on the DRG homepage under www.befundung.drg.de and will be regularly revised to the current state of scientific knowledge by the participating specialist societies and responsible working groups. CONCLUSION: This article presents structured report templates for solid and cystic pancreatic tumors to improve clinical staging (cTNM, ycTNM) in everyday radiology. KEY POINTS: · Structured report templates offer the potential of optimized radiological reporting with regard to completeness, reproducibility and differential diagnosis.. · This article presents consensus-based, structured reports for solid and cystic pancreatic lesions in CT and MRI.. · These structured reports are available open source on the homepage of the German Society of Radiology (DRG) under www.befundung.drg.de.. CITATION FORMAT: · Persigehl T, Baumhauer M, Baeßler B et al. Structured Reporting of Solid and Cystic Pancreatic Lesions in CT and MRI: Consensus-Based Structured Report Templates of the German Society of Radiology (DRG). Fortschr Röntgenstr 2020; 192: 641 - 655.

Impact of different iterative metal artifact reduction (iMAR) algorithms on PET/CT attenuation correction after port implementation.

PURPOSE: To evaluate the effect of various interactive metal artifact reduction (iMAR) algorithms on attenuation correction in the vicinity of port chambers in PET/CT. MATERIAL AND METHODS: In this prospective study, 30 oncological patients (12 female, 18 male, mean age 59.6 ± 10.5y) with implanted port chambers undergoing 18F-FDG PET/CT were included. CT images were reconstructed with standard weighted filtered back projection (WFBP) and three different iMAR algorithms (hip, dental filling (DF) and pacemaker (PM)). PET attenuation correction was performed with all four CT datasets. SUVmean, SUVmax and HU measurements were performed in fat and muscle tissue in the vicinity of the port chamber at the location of the strongest bright and dark band artifacts. Differences between HU and SUV values across all CT- and PET-images were investigated using a paired t-test. Bonferroni correction was used to prevent alpha-error accumulation (p < 0.008). RESULTS: In comparison to WFBP (fat: 94.2 ± 53.9 HU, muscle: 197.6 ± 49.2 HU) all three iMAR algorithms led to a decrease of HU in bright band artifacts. iMAR-DF led to a decrease of 159.2 % (fat: -51.9 ± 58.5 HU, muscle: 94.5 ± 55.3 HU), iMAR-hip of 138.3 % (fat: -30.3 ± 58.5, muscle: 70.4 ± 28.8) and iMAR-PM of 122.3 % (fat: -21.2 ± 47.2 HU, muscle: 72.5 ± 25.1 HU; for all p < 0.008). There was no significant effect of iMAR on SUV measurements in comparison to WFBP. CONCLUSION: iMAR leads to a significant change of HU values in artifacts caused by port catheter chambers in comparison to WFBP. However, no significant differences in attenuation correction and consecutive changes in SUV measurements can be observed.

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.

PET/MRI Versus PET/CT for Whole-Body Staging: Results from a Single-Center Observational Study on 1,003 Sequential Examinations.

Our purpose was to investigate differences between PET/MRI and PET/CT in lesion detection and classification in oncologic whole-body examinations and to investigate radiation exposure differences between the 2 modalities. Methods: In this observational single-center study, 1,003 oncologic examinations (918 patients; mean age, 57.8 ± 14.4 y) were included. Patients underwent PET/CT and subsequent PET/MRI (149.8 ± 49.7 min after tracer administration). Examinations were reviewed by radiologists and nuclear medicine physicians in consensus. Additional findings, characterization of indeterminate findings on PET/CT, and missed findings on PET/MRI, including their clinical relevance and effective dose of both modalities, were investigated. The McNemar test was used to compare lesion detection between the 2 hybrid imaging modalities (P < 0.001, indicating statistical significance). Results: Additional information on PET/MRI was reported for 26.3% (264/1,003) of examinations, compared with PET/CT (P < 0.001). Of these, additional malignant findings were detected in 5.3% (53/1,003), leading to a change in TNM staging in 2.9% (29/1,003) due to PET/MRI. Definite lesion classification of indeterminate PET/CT findings was possible in 11.1% (111/1,003) with PET/MRI. In 2.9% (29/1,003), lesions detected on PET/CT were not visible on PET/MRI. Malignant lesions were missed in 1.2% (12/1,003) on PET/MRI, leading to a change in TNM staging in 0.5% (5/1,003). The estimated mean effective dose for whole-body PET/CT amounted to 17.6 ± 8.7 mSv, in comparison to 3.6 ± 1.4 mSv for PET/MRI, resulting in a potential dose reduction of 79.6% (P < 0.001). Conclusion: PET/MRI facilitates staging comparable to that of PET/CT and improves lesion detectability in selected cancers, potentially helping to promote fast, efficient local and whole-body staging in 1 step, when additional MRI is recommended. Furthermore, younger patients may benefit from the reduced radiation exposure of PET/MRI.

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.

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.

Noise insertion in CT for cocaine body packing: where is the limit of extensive dose reduction?

BACKGROUND: To evaluate the detection rate and image quality in CT-body-packer-screening at different radiation-dose levels and to determine a dose threshold that enables a reliable detection of incorporated body packs and incidental findings with a maximum of dose saving. MATERIALS AND METHODS: We retrospectively included 27 individuals who underwent an abdominal CT with automated exposure control due to suspected body packing. CT images were reconstructed at different radiation-dose levels of 50%, 10, 5% and 1% using iterative reconstructions. All 135 CT reconstructions were evaluated by three independent readers. Reviewers determined the presence of foreign bodies and evaluated the image quality using a 5-point ranking scale. In addition, visualization of incidental findings was assessed. RESULTS: A threshold of 5% (effective dose 0.11 ± 0.07 mSv) was necessary to correctly identify all 27 patients with suspected body packing. Extensive noise insertion to a dose level of 1% (0.02 ± 0.01 mSV) led to false-positive solid cocaine findings in three patients. Image quality was comparable between 100 and 50%. The threshold for correct identification of incidental findings was 10% of the initial dose (effective dose 0.21 ± 0.13 mSv). CONCLUSIONS: Our results indicate that dose of abdominal CT for the detection of intracorporeal cocaine body packets can be markedly reduced to up to 5% of the initial dose while still providing sufficient image quality to detect ingested body packets. However, a minimum effective dose of 0.21 mSv (10% of initial dose) seems to be required to properly identify incidental 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.

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.

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.

Dual-phase hybrid 18 F-Fluoride Positron emission tomography/MRI in ankylosing spondylitis: Investigating the link between MRI bone changes, regional hyperaemia and increased osteoblastic activity.

INTRODUCTION: Focal 18 F-Fluoride uptake on blood-pool phase PET represents regional hyperaemia, while it indicates osteoblastic activity on mineralization phase PET. This study investigates the link between regional hyperaemia and osteoblastic activity in inflammatory and chronic lesions of ankylosing spondylitis (AS) of the sacroiliac joints (SIJ) using dual-phase 18 F-Fluoride PET/MRI. METHODS: Thirteen patients (six men, seven women, age: 37 ± 10 years) with active AS prospectively underwent dual-phase 18 F-Fluoride PET/MRI. Blood-pool phase PET was acquired 6 min and mineralization phase PET 40 min after injection of 158 ± 8 MBq 18 F-Fluoride. SIJ quadrants (SQ) were assessed regarding inflammatory lesions represented by bone marrow oedema (BME), chronic AS lesions such as erosion, fat deposition (FD), sclerosis and ankylosis on MRI, and regarding focal 18 F-Fluoride uptake on both PET datasets. Image quality (IQ) of both PET datasets and MRI was evaluated using a 4-point Likert scale. RESULTS: Of 104 SQ, there were 63.4% SQ with FD, 42.3% SQ with BME, 26.9% SQ with erosions, 26% SQ with sclerosis and 10.6% SQ with ankylosis. BME alone was associated with focal 18 F-Fluoride uptake in 63.6% SQ on blood-pool phase and 90.9% SQ on mineralization phase 18 F-Fluoride PET/MRI. Instead, FD, erosion, sclerosis, ankylosis were not associated with focal 18 F-Fluoride uptake on either blood-pool or mineralization phase 18 F-Fluoride PET/MRI. SQ showing BME alone or a combination of BME and chronic AS lesions had a significantly higher percentage of focal 18 F-Fluoride uptake on blood-pool phase and mineralization phase PET/MRI than SQ showing AS lesions without BME (P < 0.001). Both 18 F-Fluoride PET datasets provided high IQ, albeit IQ of mineralization phase PET was superior to blood-pool phase PET (P < 0.001). CONCLUSION: Dual-phase 18 F-Fluoride PET/MRI of the SIJ showed that inflammatory rather than chronic AS lesions are associated with regional hyperaemia and osteoblastic activity.

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.

18 F-FDG PET/MR imaging in patients with suspected liver lesions: Value of liver-specific contrast agent Gadobenate dimeglumine.

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.

Evaluation of Practical Interpretation Hurdles in 68Ga-PSMA PET/CT in 55 Patients: Physiological Tracer Distribution and Incidental Tracer Uptake.

PURPOSE: To investigate the physiologic Ga-PSMA distribution and evaluate focal or diffuse radiotracer uptake in nonprostate cancer malignancies and in incidental findings. METHODS: Ga-PSMA PET/CT scans in 55 men performed for prostate cancer (49) or renal cell carcinoma (6) staging were analyzed retrospectively. Two radiologists evaluated the datasets in 2 reading sessions. First, physiological Ga-PSMA uptake was evaluated. Second, scans were analyzed for incidental uptake. SUVmax and SUVmean were recorded. Other imaging modalities, histopathology, or clinical follow-up served as standard of reference. RESULTS: Homogenous Ga-PSMA uptake of the lacrimal glands (SUVmax, 15.7 ± 7.2), parotid glands (SUVmax, 24.4 ± 8.1), submandibular glands (SUVmax, 26.7 ± 7.1), vocal cords (SUVmax, 8.4 ± 3), Waldeyer ring (SUVmax, 10.4 ± 4.3), liver (SUVmax, 8.2 ± 2.5), spleen (SUVmax, 10.9 ± 3.9), kidneys (SUVmax, 66.4 ± 25.4), and pars descendens duodeni (SUVmax, 17.6 ± 8.9) was observed in all patients. In 65% and 36%, respectively, homogenous Ga-PSMA uptake of the colon descendens (SUVmax, 10.6 ± 9.2) and the rectum (SUVmax, 3.7 ± 1.1) was found. Approximately 22% exhibited a Ga-PSMA uptake of the thyroid (SUVmax, 4.5 ± 1.2), and 21% exhibited a Ga-PSMA uptake of the knee's synovia (SUVmax, 2.9 ± 0.2). Furthermore, Ga-PSMA uptake was found in 1 patient because of fibrous dysplasia of the right os ilium (SUVmax, 7.7). CONCLUSIONS: Physiologic distribution of Ga-PSMA comprises uptake in lacrimal and salivary glands, vocal cords, Waldeyer ring, liver, spleen, and kidneys as well as various parts of the intestine. Moreover, nonspecific tracer uptake is regularly found in the thyroid and the synovia of the knee. Incidental Ga-PSMA uptake can occasionally reveal nonprostate cancer-associated remodeling processes, such as fibrous dysplasia.

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.

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.

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.

Is integrated 18F-FDG PET/MRI superior to 18F-FDG PET/CT in the differentiation of incidental tracer uptake in the head and neck area?

PURPOSE: We aimed to investigate the accuracy of 18F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (18F-FDG PET/MRI) compared with contrast-enhanced 18F-FDG PET/computed tomography (PET/CT) for the characterization of incidental tracer uptake in examinations of the head and neck. METHODS: A retrospective analysis of 81 oncologic patients who underwent contrast-enhanced 18F-FDG PET/CT and subsequent PET/MRI was performed by two readers for incidental tracer uptake. In a consensus reading, discrepancies were resolved. Each finding was either characterized as most likely benign, most likely malignant, or indeterminate. Using all available clinical information including results from histopathologic sampling and follow-up examinations, an expert reader classified each finding as benign or malignant. McNemar's test was used to compare the performance of both imaging modalities in characterizing incidental tracer uptake. RESULTS: Forty-six lesions were detected by both modalities. On PET/CT, 27 lesions were classified as most likely benign, one as most likely malignant, and 18 as indeterminate; on PET/MRI, 31 lesions were classified as most likely benign, one lesion as most likely malignant, and 14 as indeterminate. Forty-three lesions were benign and one lesion was malignant according to the reference standard. In two lesions, a definite diagnosis was not possible. McNemar's test detected no differences concerning the correct classification of incidental tracer uptake between PET/CT and PET/MRI (P = 0.125). CONCLUSION: In examinations of the head and neck area, incidental tracer uptake cannot be classified more accurately by PET/MRI than by PET/CT.