Pelvic MRI for Endometriosis: A Diagnostic Challenge for the Inexperienced Radiologist. How Much Experience Is Enough?

PURPOSE: The purpose of this study was to investigate the impact of radiologist experience on diagnostic performance of pelvic magnetic resonance imaging (MRI) for the evaluation of endometriomas and different localisations of deep pelvic endometriosis (DPE). MATERIALS AND METHODS: In this prospective study all pelvic MRI examinations performed for pelvic endometriosis from December 2016 to August 2017 were evaluated by readers with different experience levels; junior resident (0-6 weeks of experience in female imaging), senior resident (7-24 weeks), fellow (6-24 months), and expert (10 years) in female imaging for the presence of endometriomas and DPE. Their evaluations were compared with surgery confirmed with pathology. Diagnostic performances of readers with different levels of experience were studied by the means of receiving operating characteristic curves and areas under the curve (AUC) were compared with the ones of the expert reader. RESULTS: Of 174 patients evaluated, the standard of reference was available for 59, consisting the final population of the study. The AUC for endometriomas, DPE for the posterior and anterior pelvic compartment, for rectosigmoid DPE and for overall evaluation were 0.983, 0.921, 0.615, 0.862, and 0.914 for the expert reader, 0.966 (p = 0.178), 0.805 (p = 0.001), 0.605 (p = 0.91), 0.872 (p = 0.317), and 0.849 (p = 0.0009) for the fellow level, 0.877 (p = 0.002), 0.757 (p < 0.001), 0.585 (p = 0.761), 0.744 (p = 0.239), and 0.787 (p = < 0.001) for the senior resident level and 0.861 (p = 0.177), 0.649 (p < 0.001), 0.648 (p = 0.774), 0.862 (p = 1), and 0.721 (p < 0.001) for the junior resident level. CONCLUSIONS: According to our results, interpretation of pelvic MRI for DPE should be performed by specialists as; even the performance of radiologists with up to 2 years of experience in female imaging was statistically inferior to that of experts.

The Kaiser score reliably excludes malignancy in benign contrast-enhancing lesions classified as BI-RADS 4 on breast MRI high-risk screening exams.

OBJECTIVES: MRI is an integral part of breast cancer screening in high-risk patients. We investigated whether the application of the Kaiser score, a clinical decision-support tool, may be used to exclude malignancy in contrast-enhancing lesions classified as BI-RADS 4 on breast MRI screening exams. METHODS: This retrospective study included 183 consecutive, histologically proven, suspicious (MR BI-RADS 4) lesions detected within our local high-risk screening program. All lesions were evaluated according to the Kaiser score for breast MRI by three readers blinded to the final histopathological diagnosis. The Kaiser score ranges from 1 (lowest, cancer very unlikely) to 11 (highest, cancer very likely) and reflects increasing probabilities of malignancy, with scores greater than 4 requiring biopsy. Receiver operating characteristic (ROC) curve analysis was used to evaluate diagnostic accuracy. RESULTS: There were 142 benign and 41 malignant lesions, diagnosed in 159 patients (mean age, 43.6 years). Median Kaiser scores ranged between 2 and 5 in benign and 7 and 8 in malignant lesions. For all lesions, the Kaiser score's accuracy, represented by the area under the curve (AUC), ranged between 86.5 and 90.2. The sensitivity of the Kaiser score was high, between 95.1 and 97.6% for all lesions, and was best in mass lesions. Application of the Kaiser score threshold for malignancy (≤ 4) could have potentially avoided 64 (45.1%) to 103 (72.5%) unnecessary biopsies in 142 benign lesions previously classified as BI-RADS 4. CONCLUSIONS: The use of Kaiser score in high-risk MRI screening reliably excludes malignancy in more than 45% of contrast-enhancing lesions classified as BI-RADS 4. KEY POINTS: • The Kaiser score shows high diagnostic accuracy in identifying malignancy in contrast-enhancing lesions in patients undergoing high-risk screening for breast cancer. • The application of the Kaiser score may avoid > 45% of unnecessary breast biopsies in high-risk patients. • The Kaiser score aids decision-making in high-risk breast cancer MRI screening programs.

What is the diagnostic performance of 18-FDG-PET/MR compared to PET/CT for the N- and M- staging of breast cancer?

PURPOSE: To compare the diagnostic performance of 18-FDG-PET/MR and PET/CT for the N- and M- staging of breast cancer. METHODS AND MATERIALS: Two independent readers blinded to clinical/follow-up data reviewed PET/MR and PET/CT examinations performed for initial or recurrent breast cancer staging in 80 consecutive patients (mean age = 48 ± 12.9 years). The diagnostic confidence for lesions in the contralateral breast, axillary/internal mammary nodes, bones and other distant sites were recorded. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated. The standard of reference included pathology and/or follow-up > 12 months. RESULTS: Nine of 80 patients had bone metastases; 13/80 had other distant metastases, 44/80 had axillary, 9/80 had internal mammary and 3/80 had contralateral breast tumours. Inter-reader agreement for lesions was excellent (weighted kappa = 0.833 for PET/CT and 0.823 for PET/MR) with similar reader confidence for the two tests (ICC = 0.875). In the patient-per-patient analysis, sensitivity and specificity of PET/MRI and PET/CT were similar (p > 0.05). In the lesion-per-lesion analysis, the sensitivity of PET/MR and PET/CT for bone metastases, other metastases, axillary and internal mammary nodes, contralateral tumours and all lesions together was 0.924 and 0.6923 (p = 0.0034), 0.923 and 0.923 (p = 1), 0.854 and 0.812 (p = 0.157), 0.9 and 0.9 (p = 1), 1 and 0.25 (p = 0.083), and 0.89 and 0.77 (p = 0.0013) respectively. The corresponding specificity was 0.953 and 1 (p = 0.0081), 1 and 1 (p = 1), 0.893 and 0.92 (p = 0.257), 1 and 1 (p = 1), 0.987 and 0.99 (p = 1) and 0.96 and 0.98 (p = 0.0075) respectively. CONCLUSIONS: Reader confidence, inter-reader agreement and diagnostic performance per patient were similar with PET/MR and PET/CT. However, for all lesions together, PET/MR had a superior sensitivity and lower specificity in the lesion-per-lesion analysis. KEY POINTS: • N and M breast cancer staging performance of PET/MR and PET/CT is similar per patient. • In a lesion-per-lesion analysis PET/MR is more sensitive than PET/CT especially for bone metastasis. • Readers' diagnostic confidence is similar for both tests.

Fat suppression techniques for breast MRI: Dixon versus spectral fat saturation for 3D T1-weighted at 3 T.

OBJECTIVE: To compare two fat suppression techniques used for 3D T1-weighted sequence in breast MRI (magnetic resonance imaging), namely Dixon versus spectral fat saturation (fat sat). MATERIALS AND METHODS: All breast MRI examinations performed in a Philips 3 T unit between March 2013 and October 2015 including either a Dixon or a fat sat sequence were retrospectively analyzed. The examinations were subjectively evaluated by two independent experienced readers in a scale of 5 for overall quality of fat suppression, homogeneity of fat suppression, definition of anatomic structures and focal lesions, diagnostic confidence for axillary and internal mammary regions and the presence of artifacts, 1 corresponding to excellent and 5 to non-diagnostic quality. Contrast-to-noise-ratio (CNR) measurements for muscle and focal lesions were also performed. RESULTS: Overall 161 women (mean age 51.6 ± 12.0 years) underwent 189 MR examinations, 113 with the fat saturation and 76 with the Dixon sequence. Interobserver variability was good (kappa = 0.757). In all subjectively evaluated parameters, the Dixon sequence was superior to the fat sat (p < 0.05). Mean values of CNR for muscle and focal lesions were 9.98 (±4.2), 17.9 (±7.53) for the fat sat and 18.3 (±10.4) and 29.3 (±14.1) for the Dixon sequence, respectively (p < 0.001). CONCLUSION: 3D T1 Dixon sequence is superior to fat sat for dedicated breast MRI at 3 T, in terms of efficiency of fat suppression and image quality with the added advantage of optimal exploration of the axillary areas.

CT vaginography: a new CT technique for imaging of upper and middle vaginal fistulas.

OBJECTIVE: Different types of vaginal fistulas is a relatively uncommon condition in the Western world but very frequent in developing countries. In the past, conventional vaginography was the radiological examination of choice for exploring this condition. CT and MRI are now both used for this purpose. Our objective was to test the feasibility and to explore the potential role of a new CT imaging technique implementing vaginal introitus obstruction and opacification of the vagina with iodine contrast agent, to show patency of a fistula. METHODS: We describe the technical protocol of CT-vaginography as performed in Geneva University Hospitals, including vaginal catheterization with a Foley catheter and obstruction of the introitus by inflating the balloon of the catheter. We also report three cases of patients with suspected vaginal fistula who underwent CT-vaginography. RESULTS: The examinations were technically successful. In one patient, it revealed the presence of fistulous pathways from the vaginal fornix along the bilateral infected surgical prostheses. In a second patient, it showed a fistula between the vagina and the necrotic cavity of a recurrent cervical cancer. In a third patient, it proved the absence of a suspected vaginal fistula. CONCLUSION: CT-vaginography is a technically feasible CT protocol that provides anatomical and functional information on clinically suspected vaginal fistulas. Advances in knowledge: After the abandon of conventional vaginography in the era of transaxial imaging, the current modalities of imaging vaginal fistulas provide excellent anatomical detail but less functional information concerning the permeability of a vaginal fistulous pathway. We propose the use of CT-vaginography, a technical protocol that we describe in detail.

Value of liver computed tomography with iodixanol 270, 80 kVp and iterative reconstruction.

AIM: To evaluate the image quality of hepatic multidetector computed tomography (MDCT) with dynamic contrast enhancement. METHODS: It uses iodixanol 270 mg/mL (Visipaque 270) and 80 kVp acquisitions reconstructed with sinogram affirmed iterative reconstruction (SAFIRE(®)) in comparison with a standard MDCT protocol. Fifty-three consecutive patients with known or suspected hepatocellular carcinoma underwent 55 CT examinations, with two different four-phase CT protocols. The first group of 30 patients underwent a standard 120 kVp acquisition after injection of Iohexol 350 mg/mL (Accupaque 350(®)) and reconstructed with filtered back projection. The second group of 25 patients underwent a dual-energy CT at 80-140 kVp with iodixanol 270. The 80 kVp component of the second group was reconstructed iteratively (SAFIRE(®)-Siemens). All hyperdense and hypodense hepatic lesions ≥ 5 mm were identified with both protocols. Aorta and portal vessels/liver parenchyma contrast to noise ratio (CNR) in arterial phase, hypervascular lesion/liver parenchyma CNR in arterial phase, hypodense lesion/liver parenchyma CNR in portal and late phase were calculated in both groups. RESULTS: Aorta/liver and focal lesions altogether/liver CNR were higher for the second protocol (P = 0.0078 and 0.0346). Hypervascular lesions/liver CNR was not statistically different (P = 0.86). Hypodense lesion/liver CNR in the portal phase was significantly higher for the second group (P = 0.0107). Hypodense lesion/liver CNR in the late phase was the same for both groups (P = 0.9926). CONCLUSION: MDCT imaging with 80 kVp with iterative reconstruction and iodixanol 270 yields equal or even better image quality.

Clinical utility of 18F-FDG-PET/MR for preoperative breast cancer staging.

OBJECTIVE: To evaluate the performance of 18F-fluorodeoxyglucose (FDG) positron emission tomography magnetic resonance imaging (PET/MR) for preoperative breast cancer staging. METHODS: Preoperative PET/MR exams of 58 consecutive women with breast cancer were retrospectively reviewed. Histology and mean follow-up of 26 months served as gold standard. Four experienced readers evaluated primary lesions, lymph nodes and distant metastases with contrast-enhanced MRI, qualitative/quantitative PET, and combined PET/MR. ROC curves were calculated for all modalities and their combinations. RESULTS: The study included 101 breast lesions (83 malignant, 18 benign) and 198 lymph node groups, (34 malignant, 164 benign). Two patients had distant metastases. Areas under the curve (AUC) for breast cancer were 0.9558, 0.8347 and 0.8855 with MRI, and with qualitative and quantitative PET/MR, respectively (p = 0.066). Sensitivity for primary cancers with MRI and quantitative PET/MR was 100 % and 77 % (p = 0.004), and for lymph nodes 88 % and 79 % (p = 0.25), respectively. Specificity for MRI and PET/MR for primary cancers was 67 % and 100 % (p = 0.03) and for lymph nodes 98 % and 100 % (p = 0.25). CONCLUSIONS: In breast cancer patients, MRI alone has the highest sensitivity for primary tumours. For nodal metastases, both MRI and PET/MR are highly specific. KEY POINTS: • MRI alone and PET/MR have a similar overall diagnostic performance. • MRI alone has a higher sensitivity than PET/MR for local tumour assessment. • Both MRI and PET/MR have a limited sensitivity for nodal metastases. • Positive lymph nodes on MRI or PET/MR do not require presurgical biopsy.