Faculty Bibliography

Approximately 15% of men with newly diagnosed prostate cancer have high-risk disease. Imaging is critically important for the diagnosis and staging of these patients, and also for the selection of management. While established prostate cancer staging guidelines have increased the appropriate use of imaging, underuse for high-risk prostate cancer remains substantial. Several factors affect the utility of initial diagnostic imaging, including the variable definition of high-risk prostate cancer, variable guideline recommendations, poor accuracy of existing imaging tests, and the difficulty in validating imaging findings. Conventional imaging modalities, including CT and radionuclide bone scan, have been employed for local and metastatic staging, but their performance characteristics have generally been poor. Emerging modalities including multiparametricMRI, positron emission tomography (PET)-CT, and PET-MRI have shown increased diagnostic accuracy and could improve accuracy in staging patients with high-risk prostate cancer.

OBJECTIVE: The purpose of this study was to determine whether the simultaneous MRI evaluation of Hill-Sachs lesions and glenoid bone loss by use of the on-track off-track method can be used to predict engagement during arthroscopy. MATERIALS AND METHODS: The records of 75 consecutively registered patients (60 male patients, 15 female patients) with a history of previous anterior shoulder instability who underwent preoperative MRI of the shoulder and arthroscopy at our institution were reviewed. A total of 76 MRI examinations were included. Two readers reviewed the MR images of each patient blindly and independently and used the on-track off-track method to predict engagement. These results were compared with the findings related to engagement seen during arthroscopy, which was performed by one of seven orthopedic surgeons. Statistical analyses included Fisher exact test, logistic regression, ROC analysis, and calculation of intraclass correlation coefficients. RESULTS: Using the on-track off-track technique of reading MR images, the reviewers correctly predicted 13 of the 18 engaging (off-track) lesions (sensitivity, 72.2%). Among the 58 shoulders that did not engage (on-track), they correctly predicted 51 (specificity, 87.9%). Overall, the accuracy of the on-track off-track method was 84.2% with a positive predictive value of 65.0% and negative predictive value of 91.1%. CONCLUSION: Our study showed that the on-track off-track method can be used in MRI to accurately assess the bipolar bone loss seen in patients with anterior shoulder instability for predicting the presence of engaging, or off-track, lesions. This information can be used preoperatively to help guide the type of stabilization procedure performed on patients with anterior shoulder instability.

OBJECTIVE: The purpose of this article is to review the normal anatomy and pathologic conditions of the shoulder on the basis of the appearance on MR and ultrasound images obtained during performance of abduction external rotation and flexion adduction internal rotation positional maneuvers. CONCLUSION: Positional MRI and ultrasound are highly useful in evaluation of the shoulder. Knowledge of the normal appearance of anatomic structures and pathologic changes in nontraditional imaging planes is necessary to avoid pitfalls in interpretation.

Purpose: A routine shoulderMRI protocolwith multi-planar 2D fast spin echo (FSE) sequences usually requires 15-20 min of imaging time.With recent technological advances of multichannel coils and MRI systems, these same sequences can nowbe acquired rapidly using parallel imaging. The purpose of this study was to evaluate if a 5-min shoulder MRI protocol using parallel imaging is interchangeable with a routine shoulder MRI protocol. Materials and Methods: 153 shoulder MRI exams performed on an 8 channel 3 T system (Siemens Verio) with a 4 channel shoulder coil (Invivo) were retrospectively reviewed. All scans included a routine 5 sequence protocol (coronal oblique fat suppressed (fs) PD-weighted and T2-weighted FSE sequences, sagittal oblique fs fluid sensitive and non fs T1-weighted FSE sequences, and an axial fluid sensitive FSE sequence) and 4 fast sequences with an acceleration factor of 2 and slightly larger voxels (coronal oblique, sagittal oblique, and axial fs fluid sensitive sequences and a sagittal oblique non fs T1-weighted sequence). After separation and anonymization of the two protocols, 2 musculoskeletal radiologists independently evaluated the following structures: supraspinatus and infraspinatus tendons (normal/tendinosis, low grade partial-thickness tear, high grade partial-thickness tear, full thickness tear); subscapularis tendon (normal/tendinosis, partial thickness tear, incomplete full thickness tear, and complete full thickness tear); rotator cuff muscle fatty infiltration (none, minimal, mild, moderate, marked); biceps tendon (normal, tendinosis/ partial tear, complete tear); and labrum by quadrant (intact, tear). A test for interchangeability between the fast and routine protocols was performed by comparing the difference between the inter-reader agreement for the routine protocol with the inter-reader agreement when 1 reader was reading the routine protocol and the other reader was reading the fast protocol. Results: The mean age of the patients was 46.75 years (18 - 80) with 85 men and 68 women. The average imaging time was 5 min, 23 s (4:47 - 6:45) for the fast protocol and 14 min, 6 s (12:43 - 16:34) for the routine protocol. The inter-reader agreement for supraspinatus/ infraspinatus pathology was 79.5 % for the routine protocol versus 80.8 % between the routine and fast protocols (95 % CI for difference -5.5 to 2.9 %, p = 0.539). The agreement for subscapularis pathology was 83.4 % for the routine protocol versus 83.4 % between the two protocols (95 % CI -3.8 to 3.8%, p = 1.0). The agreement on muscle fatty infiltration was 89.4 % for the routine protocol versus 91.4 % between the two protocols (95 % CI -4.5 to 0.6 %, p = 0.141). The agreement on biceps pathology was 70.9 % for the routine protocol versus 68.2 % between the two protocols (95 % CI -2.4 to 7.7 %, p = 0.302). The agreement on labrum was between 77.5 and 94.0 % for the routine protocol versus 75.5-93.4 % between the two protocols (95 % CI -3.2 to 6.6 %, p value=0.105-1.0). Conclusion: A 5-min shoulder MRI is clinically interchangeable with a routine shoulderMRI for evaluation of the rotator cuff, biceps tendon and glenoid labrum. Using a 5-min protocol could improve the efficiency and lower the costs of performing a shoulder MRI

Purpose: Whole body PET-MRI to evaluate for osseous malignancy is a novel rapidly emerging modality. While several studies have shown the individual utility of Fluorine-18 labelled fluorodeoxyglucose (FDG) and sodium fluoride (NaF) PET tracers and diffusion weighted imaging (DWI) MRI in evaluating metastatic and primary osseous malignancy, there is no literature directly comparing all three parameters using whole body hybrid PET-MRI. The purpose of this pilot study is to directly compare FDG and NaF PET scans and DWI ADC mapping for detecting osseous malignancy on whole body PET-MRI. Materials and Methods: A retrospective review of 8 biopsy proven malignant bone lesions (7 CT guided biopsies and 1 surgical biopsy) and 11 benign bone lesions were evaluated in 13 patients who had whole body FDG PETMRI and/or NaF PET-MRI including DWI with apparent diffusion coefficient (ADC) mapping. For each bone lesion, the SUVmax, ADCmin, and ADCmean was calculated. On PET, criteria for malignancy was prominent focal round or mass-like tracer uptake morphology, and criteria for benign lesion was absence of increased uptake relative to background bone or linear uptake morphology consistent with benign disease. On DWI, criteria for malignancy was ADC value in the range of 0.7 - 1.0 x 10-3 mm2/s as previously published, and criteria for benign was an ADC value outside of this range. The reference standard for malignancy was biopsy results and the reference standard for benign lesion was characteristic benign appearance on conventional MRI sequences (T1, T2, STIR). The sensitivity and specificity of each measurement was calculated. McNemar tests were used to compare diagnostic tests based on each measure in terms of accuracy relative to the reference standard diagnosis. Results: 8 patients (5 females, 3 males, avg. age 60) had malignant bone lesions and 7 patients (3 females, 4 males, avg. age 65) had benign bone lesions which were evaluated. Malignant lesions included four metastatic breast cancer, two metastatic prostate cancer, one multiple myeloma, and one Ewing's sarcoma. Benign lesions included eight degenerative, one fracture, two enthesopathic, one hemangioma, and one avascular necrosis. The sensitivities, specificities, and accuracies of FDG PETwere 50, 50, 50 %, of NaF PETwere 100, 67, 75%, of ADCmin were 88, 100, 95%, of ADCmean were 63, 100, 86 %. Conclusion: Our preliminary data suggests that when using whole body PET-MRI to evaluate for osseous malignancy, NaF may have the highest sensitivity compared to FDG and DWI, and DWI has the highest specificity and accuracy with ADCmin being more accurate than ADCmean. This could be useful clinical information for diagnosis, treatment, surveillance and surgical/biopsy planning and warrants further investigation

Purpose: To evaluate the diagnostic accuracy of NaF PET-MRI in differentiating bone metastases from benign bone lesions, such as degenerative changes, in patients with metastatic prostate cancer.
Material(s) and Method(s): 11 patients with prostate cancer and bone metastases underwent NaF PET-MRI. The MRI included anatomic T1/T2/ STIR sequences as well as diffusion-weighted imaging (DWI) using b values of 50 and 800. Each bone lesion was tabulated as benign or metastatic for each image type using either NaF PET-MRI, NaF PET-CT, or biopsy as the gold standard. Bone scintigraphy was available in 7 of the 11 patients and read independently without knowledge of the PET-MR results. SUVmax on PET and ADCmin, mean, max on DWI was measured for each lesion. Mixed model analysis of variance (ANOVA) was used to compare benign and malignant lesions in terms of each measure. Specificity, sensitivity, and overall accuracy for discrimination of benign and malignant lesions using each modality (BS, PET, DWI, PET/MRI) were calculated. Area under the ROC curve (AUC) achieved by each measure, threshold to define lesions as test positive for malignancy that maximized the average sensitivity and specificity, and sensitivity and specificity achieved at the indicated threshold were calculated.
Result(s): 36 total bone lesions were evaluated, including 21 metastases and 15 benign lesions. ADCmean was significantly lower (p=0.008) and SUVmax significantly higher (p=0.024) among malignant lesions than benign lesions. No significant difference between malignant and benign lesions was seen with ADCmin (p=0.09) and ADCmax (p=0.140). Specificity, sensitivity, and overall accuracy of each modality was: 100%, 31%, 65% for BS; 53%, 86%, 72% for DWI; 13%, 100%, 64% for PET; 100%, 86%, 92% for PET/MRI. AUC, threshold, and achieved sensitivity and specificity at that threshold for each parameter was: 0.7, >17.95, 62%, 80% for SUVmax; 0.67, <=1.377, 56%, 87% for ADCmax; 0.8, <=0.6224, 67%, 93% for ADCmean; 0.6, <=0.221, 82%, 47% for ADCmin. AUC of ADCmin was significantly lower than that of ADCmean (p=0.012). There were no other significant differences between measures in terms of AUC (p>0.1).
Conclusion(s): NaF PET-MRI as a hybrid imaging study shows higher specificity, sensitivity, and overall accuracy than BS and PET or DWI in isolation in differentiating between metastatic and benign bone lesions. Accurately defining the number of lesions has important treatment implications as prostate cancer treatment is generally based on disease burden

Purpose: To see if 3D imaging could improve our understanding of rotator cuff tendon tear shapes on MRI.
Method(s): We performed a retrospective review of 1.5T/3T MR examinations, conducted over an 18-month period, of patients with arthroscopically proven full- thickness rotator cuff tears. Two orthopaedic surgeons reviewed the operative reports/arthroscopic photos for each patient, and characterized, in consensus, the shape of the tear based on a comparison of the tear's width (size) and length (retraction), and involvement of the rotator interval without measurements into the following categories: crescent, longitudinal, U or L-shaped longitudinal, and massive- type. Two musculoskeletal radiologists reviewed the pre-operative MR examination for each patient independently/blind to the arthroscopic findings. Initially, the readers characterized the shape of the tendon tears by reviewing the standard 2DMR sequences and using the same criteria as the surgeons used during their review of the scope images. Next, the readers measured and documented the width and length of each tendon tear using the 2D images. The shape of the tear was then classified based on a previously published MR-based system as either crescent, longitudinal, U or L-shaped, or massive. Four weeks after the initial imaging evaluation, 3DMR reconstructions of each tear were reviewed and the shape documented by each radiologist independently/blind to the arthroscopic results using the same system used by our orthopaedic colleagues. These results were then compared to the 2D imaging evaluations and arthroscopic findings. Statistical analysis included 95% confidence intervals, McNemar test, and intra-class correlation coefficients.
Result(s): A total of 34 patients were included in the study; 21 had crescent shaped tears and 13 had longitudinal tears during arthroscopy. Of the 13 longitudinal tears, 8 were subtyped as U-shaped, while 5 were described as L-shaped. 6 of the 13 longitudinal tears were additionally classified as massive-type. There was no significant difference when comparing the accuracy of the tear shape characterizations made on 2DMR imaging without measurements (pre) and with measurements (post). The accuracy for differentiating between crescent shaped, longitudinal, and massive tears was the same for reader 1, 70.6% (24/34; p=1) and more accurate using the post 2D data for reader 2 (67.6%(post) vs. 61.8%(pre), p=0.5). The accuracy for tear shape characterization between crescent and longitudinal using the 3D reconstructions for reader #1 was 97.1%(33/34) and 88.2% (30/34) for reader #2. When this characterization included subclassifying the longitudinal tears into U or-L shaped, the accuracy for reader #1 was 97.1% and 82.4% for reader #2. When further characterizing the longitudinal tears as massive or not, both readers had an accuracy of 76.9% (10/13). The overall accuracy of the 3D reconstructions was 82.4% (56/68), significantly different (p=0.021) from the post 2D accuracy (64.7%) and pre 2D accuracy (60.3%, p=0.001). The intraclass correlation coefficient for the 2D measurements of width and length were 0.81, moderate agreement, for width and 0.95, strong agreement, for length.
Conclusion(s): Our study has demonstrated that 3DMR reconstructions of the rotator cuff improve the accuracy of characterizing rotator cuff tear shapes compared to the current 2DMR imaging based techniques

Magnetic resonance imaging (MRI) evaluation of the postoperative shoulder presents technical and diagnostic challenges related to imaging artifacts from hardware and micrometallic shavings, postsurgical scarring, and morphological alterations. Improved visualization of postoperative shoulder anatomy and pathology can be obtained with the use of metal artifact reduction techniques as well as MR arthrography. In this article we review the MR techniques that are designed to address these technical and diagnostic challenges, and we discuss the definitions and indications, normal MRI appearance, and complications of routine surgical procedures for treatment of injuries to the rotator cuff, labral ligamentous complex, and biceps tendon. J. Magn. Reson. Imaging 2014;40:1280-1297. (c) 2014 Wiley Periodicals, Inc.

OBJECTIVE: The annular ligament is one of the major stabilizers of the proximal radioulnar joint. However, it is one of the least studied structures in the lateral elbow because of imaging challenges and low pathologic incidence. This article will examine the anatomy of the annular ligament, its biomechanics, and its functional importance. Eight surgically proven cases of annular ligament abnormality in patients with posterolateral and nursemaid elbow, along with the associated findings, are presented. CONCLUSION: Adequate understanding of the anatomy and familiarity with the associated injuries that can be seen in annular ligament displacement or rupture will improve detection of annular ligament abnormality.

The rotator interval contains several important anatomical structures that contribute to the stability and normal function of the shoulder joint including the biceps tendon, coracohumeral ligament, superior glenohumeral ligament, rotator interval capsule, anterior fibers of the supraspinatus tendon, and superior fibers of the subscapularis tendon. Rotator interval pathology is associated with biceps instability, glenohumeral instability, and adhesive capsulitis, all of which can be challenging to clinically diagnose and treat. The complex anatomy and orientation of the rotator interval structures within a relatively small space can make it difficult to evaluate by imaging; however, improvements in MR technology have allowed better detection of disease in this region. Furthermore, the rotator interval is not routinely evaluated arthroscopically unless the clinical examination or imaging findings suggest pathology at this level. Imaging, therefore, can play a significant role in helping the clinician make the diagnosis and initiate appropriate treatment. This article discusses the normal anatomy and biomechanics of the rotator interval and its structures as well as the normal and pathologic appearances on imaging and the treatment options of abnormalities of structures in this region.