Ramon Gheno

Peripheral tumor and tumor-like neurogenic lesions

Neoplasms of neurogenic origin account for about 12% of all benign and 8% of all malignant soft tissue neoplasms. Traumatic neuroma, Morton neuroma, lipomatosis of a nerve, nerve sheath ganglion, perineurioma, benign and malignant peripheral nerve sheath tumors (PNST) are included in this group of pathologies. Clinical and radiologic evaluation of patients with neurogenic tumors and pseudotumors often reveals distinctive features. In this context, advanced imaging techniques, especially ultrasound (US) and magnetic resonance (MR) play an important role in the characterization of these lesions. Imaging findings such as location of a soft tissue mass in the region of a major nerve, nerve entering or exiting the mass, fusiform shape, abnormalities of the muscle supplied by the nerve, split-fat sign, target sign and fascicular appearance should always evoke a peripheric nerve sheath neoplasm. Although no single imaging finding or combination of findings allows definitive differentiation between benign from malign peripheric neurogenic tumors, both US and MR imaging may show useful features that can lead us to a correct diagnosis and improve patient treatment. Traumatic neuromas and Morton neuromas are commonly associated to an amputation stump or are located in the intermetatarsal space. Lipomatosis of a nerve usually appears as a nerve enlargement, with thickened nerve fascicles, embedded in evenly distributed fat. Nerve sheath ganglion has a cystic appearance and commonly occurs at the level of the knee. Intraneural perineuroma usually affects young people and manifests as a focal and fusiform nerve enlargement. In this article, we review clinical characteristics and radiologic appearances of these neurogenic lesions, observing pathologic correlation, when possible.

Accessory head of biceps brachii muscle: anatomy, histology, and MRI in cadavers.

OBJECTIVE The purpose of our study is to describe and define an anatomic variation located close to the bicipital groove using MRI with gross anatomic and histologic correlation in cadavers. MATERIALS AND METHODS Ten fresh male human shoulders were harvested and used in this investigation. They were derived from persons with a mean age of death of 78.9 years (age range, 58-92 years). MR arthrography using proton density-weighted sequences was used to obtain images in axial, coronal, and sagittal planes. After imaging, the specimens were cut in axial, coronal, and sagittal sections using a band saw. The slices were then photographed to allow correlation with the MR arthrographic images, followed by histologic analysis. RESULTS Two anomalous tendons, both intimate with the tendon of the long head of the biceps brachii muscle in the bicipital groove, were recognized. The origin of both tendons was in the greater tuberosity near the articular capsule. These structures had a muscular belly that was joined with the other biceps bellies. At the level of the bicipital groove, the anomalous tendons appeared as hypointense structures in proton density-weighted images, with a mostly flat morphology in axial and coronal planes. The average dimensions of these structures were 45.5 (craniocaudal)x6.2 (anteroposterior)x0.85 (mediolateral) mm. CONCLUSION The MR images, gross anatomic inspection, and histologic information led us to conclude that these anomalous structures were accessory heads of the biceps brachii muscle.

Ulnomeniscal Homologue of the Wrist: Correlation of Anatomic and MR Imaging Findings

PURPOSE To evaluate the anatomy of the ulnar side of the wrist in the region of the triangular fibrocartilage (TFC) complex, with special focus on the ulnomeniscal homologue (UMH) and its relationship to surrounding structures. MATERIALS AND METHODS Institutional review board approval and informed consent were not required. Ten upper extremities were harvested from the nonembalmed cadavers of four women and six men (age range at death, 56-97 years; mean age at death, 83 years) and used according to institutional guidelines. Magnetic resonance (MR) imaging and MR arthrography of the wrist were performed with the wrist in neutral position, maximal ulnar deviation, and maximal radial deviation by using intermediate-weighted sequences. The specimens were cut into 4-mm-thick sections that corresponded to the MR imaging planes. The gross anatomic features of the UMH and its relationship to adjacent structures were evaluated and compared with imaging findings. UMH variants, as described in previous articles on purely anatomic studies, were sought on MR images. MR findings of the wrist in neutral position were compared with those of the wrist in maximal ulnar and radial deviations. Histologic examination was used to further elucidate the structure of the UMH. RESULTS The UMH displayed complex anatomic features because of its obliquely oriented course. However, it could be divided into styloid, radioulnar, and collateral components and a distal insertion. The UMH variants described in previously published studies could be identified, but evaluation results were highly dependent on the wrist position at imaging. CONCLUSION The anatomy of the UMH is complex. For assessment of the UMH and the ulnar side of the TFC complex, coronal MR arthrography with the wrist in neutral position or radial deviation might be superior to standard MR imaging.

Anatomical study of the pisotriquetral joint ligaments using ultrasonography

ObjectiveThe aim of this study was to demonstrate that ultrasonography may allow a precise assessment of the primary stabilizers of pisotriquetral joint (pisohamate, pisometacarpal, and ulnar pisotriquetral ligaments).Methods and materialsThis study was initially undertaken in eight cadavers. Metal markers were placed in the ligaments using ultrasonographic guidance, followed by the dissection of the wrists. High-resolution ultrasonography was then performed in 15 volunteers (30 wrists) for the analysis of the presence, appearance, and thickness of the ligaments.ResultsAt dissection, the metal markers were located in the ligaments or immediately adjacent to them, confirming that they were correctly depicted using ultrasonography. The three ligaments could also be identified in each volunteer. The optimal positioning of the probe and the dynamic maneuvers of the wrist allowing the strain of these ligaments could be defined. No significant changes in the appearance and thickness of the ligaments could be observed.ConclusionsThe three ligaments stabilizing the pisotriquetral joint can be identified using ultrasonography. Further studies are now required to know whether this knowledge may be useful in the assessment of pain involving the ulnar part of the wrist.

Ultrasonographic evaluation of degenerative changes in the distal radioulnar joint: correlation of findings with gross anatomy and MR arthrography in cadavers.

OBJECTIVE To determine the accuracy of ultrasonography (US) in the evaluation of degenerative changes in the distal radioulnar joint (DRUJ). METHODS AND MATERIALS Ten cadaveric specimens were obtained. US evaluation of cartilage degeneration and thickness was performed by two independent and blinded readers (R1 and R2). Gross anatomy and MR arthrography evaluated by two readers in consensus served as the reference standard. The joint surface not accessible to US was measured. RESULTS US interreader agreement was non-existent for cartilage thickness measurements and moderate for cartilage degeneration grading (weighted kappa = 0.41). Comparing US and MR imaging evaluation, there was no correlation between US R1 and MR imaging (Pearson correlation coefficient [PCC] = 0.352) and a moderate correlation between US R2 and MR imaging (PCC = 0.570) concerning cartilage thickness measurements. Concerning cartilage degeneration grading, there was a moderate to strong (R1 Spearman correlation coefficient [SCC] = 0.729)/R2 SCC = 0.767) correlation concerning cartilage degeneration grading. Comparing US and gross anatomic evaluation, there was no correlation for US R1 (PCC = 0.220) and a strong correlation for US R2 (PCC = 0.922) concerning cartilage thickness measurements, and a strong to moderate correlation (R1 SCC = 0.808/R2 SCC = 0.597) concerning cartilage degeneration grading. The mean sector of the articular surface of the ulna head not accessible to US was 13°. CONCLUSION In conclusion the DRUJ is accessible to US except in the central 13° sector of the joint surface. US was approved to be sufficient in demonstrating advanced stages of cartilage degeneration. Thus, US of the DRUJ is recommended in patients suffering from ulnar-sided wrist pain.

Morphology of the Distal Radioulnar Joint: Cadaveric Study With MRI and MR Arthrography With the Forearm in Neutral Position, Pronation, and Supination

OBJECTIVE The purpose of this study was to evaluate the physiologic extent and thickness of the cartilage and bare areas of the distal radioulnar joint with gross anatomic examination, MRI, and MR arthrography with the forearm in neutral position, maximal pronation, and maximal supination. MATERIALS AND METHODS MRI and MR arthrography were performed on 10 cadaveric specimens (mean age at death, 82.9 years; range, 56-97 years) with the forearm in neutral position, maximal pronation, and maximal supination. Cartilage surface and thickness were assessed, and degenerative changes and bare areas were evaluated in consensus by two musculoskeletal radiologists. Gross anatomic and histologic examinations were used as the reference standard. RESULTS MRI in maximal pronation and supination was helpful in evaluation of the ulnar cartilage. In the axial plane, any change in cartilage thickness in the ulnar head was related to chondral degeneration. In the coronal plane, cartilage thickness proved to be an unreliable sign in the assessment of chondral degeneration. The presence of osteophytes in the proximal aspect of the joint was easily detected and proved to be a reliable criterion for joint degeneration. Bare areas were found at the proximal and volar attachments of the joint capsule. CONCLUSION Detailed knowledge of the anatomy of the distal radioulnar joint should allow more accurate assessment of degenerative changes and localization of erosions in inflammatory joint disease. Imaging with the forearm in maximal pronation and supination can improve visualization of the cartilage of the ulnar head.

Edematous Processes Within Kager Fat Pad: Magnetic Resonance Imaging, Gross Anatomical, and Histological Studies in Cadavers With Clinical Correlation

Objective: To demonstrate the anatomical features of Kager fat pad (KFP) and its fasciae using magnetic resonance imaging, gross anatomy, and histology in cadavers; and to correlate the data with image findings in patients. Methods: The KFP was analyzed in 10 fresh human cadavers and 152 clinical cases. The retrospective clinical study was institutional review board approved. The specimens were studied by magnetic resonance imaging and sectioned for anatomical/histological correlation. Clinical cases were selected to evaluate the frequency, distribution, and patterns of edema/inflammation in KFP. The square of the Pearson product moment correlation coefficient and Student t tests were performed. Results: Fasciae about KFP are double layered and derived from the union of the fascia of the leg and flexor and peroneal retinacula. Edema in KFP could be divided into diffuse, confined anteriorly, confined posteriorly, and confined externally. Confined patterns of edema were associated with paratenonitis and fluid in the Achilles bursae (P < 0.05). Conclusions: Four patterns of edema occur in KFP. Paratenonitis and bursal fluid were associated with confined edematous patterns. The double layer about KFP may contain edema that affects this region.

Can osseous landmarks in the distal medial humerus be used to identify the attachment sites of ligaments and tendons: paleopathologic–anatomic imaging study in cadavers

ObjectiveTo describe osseous landmarks that allow identification of the attachments of the ligaments and tendons in the distal medial aspect of the humerus.Materials and methodsReliable osseous landmarks in the distal medial aspect of the humerus were identified in 34 well-preserved specimens from a paleopathologic collection. These osseous landmarks were then sought in magnetic resonance (MR) images of ten cadaveric elbow specimens so that the ease of their visualization and optimal imaging plane could be assessed. To assign these osseous landmarks to specific attachments of the tendons and ligaments in the distal medial humerus, we cut the specimens in slices and photographed and examined them. Subsequently, the prevalence of these osseous landmarks as well as the attachment sites of the tendons and ligaments in this location was determined.ResultsWe determined ten reliable osseous landmarks in the distal medial aspect of the humerus, their prevalence and ease of identification, and their relationship to the attachments of the tendons and ligaments at the medial distal humerus.ConclusionIt is possible to use osseous landmarks at the distal medial humerus to facilitate identification of the different attachments of tendons and ligaments when MR images of the elbow are assessed.