Biomedical subjects
Publications and source records attributed to D Resnick.
The authors review various pedal conditions affecting the rearfoot, including plantar fasciitis, Achilles tendon pathology, fractures, arthritides, coalitions, and tumors. Various diagnostic imaging modalities such as routine radiography, radionuclide bone scanning, computed tomography, and magnetic resonance imaging are discussed.
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Silicone synovitis is a known complication of silicone implants used in orthopedic surgery for joint reconstruction. It has been studied with routine radiography; however, no report on magnetic resonance imaging abnormalities of this condition exist in the literature. This article reports on five patients with silicone synovitis studied by magnetic resonance imaging. All patients showed hypointense implants that were deformed, fragmented or subluxed, and intra- and periarticular silicone particles were evident on T1- and T2-weighted images.
OBJECTIVE: To describe the imaging characteristics of stress fractures of the heads of the metatarsal bones, emphasizing their difference from the more common metatarsal shaft and neck stress fractures. DESIGN AND PATIENTS: Eight patients with stress fractures of the head of one or more of the metatarsal bones were seen in a 5-year period. The four men and four women were 31-72 years of age (mean 52.3 years). Three of the patients were active in sports. Three patients had underlying conditions predisposing to insufficiency fracture and one patient had had a bunionectomy on the affected foot 5 years previously. Plain radiographs and magnetic resonance (MR) imaging studies were reviewed in a retrospective feature. RESULTS: Plain radiographs showed subchondral sclerosis of the metatarsal heads in all but one case, in which MR imaging, performed 6 weeks after the onset of symptoms, demonstrated an area of abnormal signal intensity in the head of the third metatarsal bone consistent with marrow edema. CONCLUSION: Stress fractures (i.e., fatigue and insufficiency fractures) of the head of the metatarsal bones occasionally occur. Because of their less recognized appearance on routine radiographs and MR images, they are frequently overlooked.
Condensing osteitis of the clavicle is a rare, benign, usually painful condition leading to sclerosis of the medial end of the clavicle. In the English language literature, this has only been reported in women since its original description by Brower et al. in 1974 [1]. We report a clavicular lesion occurring in a man that is clinically, radiographically, and histologically identical to described cases of condensing osteitis.
Magnetic resonance (MR) imaging provides useful information in the evaluation of peripheral nerves. Recent advances in MR imaging allow for detailed depiction of the soft tissue structures of the elbow joint. Three major nerves are present about the elbow. Six cadaveric elbows were imaged to depict the normal anatomy of these nerves and to determine the best plane and position of the elbow for optimal visualization of each nerve. Axial images of the elbow in full extension with the forearm in supination allow identification of all major nerves. Axial images with the elbow in full flexion allow accurate assessment of the cubital tunnel and the ulnar nerve. Axial images of the elbow in full extension with the forearm in pronation are helpful for assessment of the median and radial nerves in the forearm.
OBJECTIVE: To evaluate the accuracy of MR arthrography in determining the thickness of articular cartilage of the humeral head and glenoid fossa. DESIGN AND PATIENTS: MR arthrography of the glenohumeral joint was performed in 17 cadaveric shoulders. Articular cartilage thickness was measured on the MR arthrographic images and corresponding anatomic sections. RESULTS: The correlation coefficients for MR arthrographic measurement versus anatomic measurement of the cartilage thickness were 0.7324 and 0.8757 for humeral head and glenoid fossa, respectively. With regard to the humeral head, there was a tendency to overestimate regions of thin cartilage and underestimate regions of thick cartilage. This tendency was not found in the assessment of glenoid cartilage. The mean of the absolute value of MR-anatomic differences was similar on the glenoid side (0.27 mm) and the humeral side (0.29 mm). The accuracy of measurement was significantly better on the glenoid side (Fisher's r-to-Z transformation: Z=5.21, P=0.000001). CONCLUSION: MR arthrography causes a moderate degree of error in the naked-eye measurement of the cartilage of the glenohumeral joint. The accuracy is higher on the glenoid side than on the humeral side.
A 39-year-old woman suffered from swelling and tenderness of the right leg for 31 years. Imaging studies showed a large soft tissue lesion on the right side extending from the proximal portion of the thigh to the ankle. She underwent several operations due to the leg mass and associated equinovarus deformity of the right ankle. The pathologic findings were those of an ossified cavernous hemangioma. This appears to be one of the largest hemangiomas to be reported. It revealed the three types of calcification characteristic of hemangiomas. Equinovarus deformity of the ankle caused by contracture of the calf in this case was probably related to repeated bleeding.
OBJECTIVE: To compare partial flexion true sagittal (FS) magnetic resonance (MR) images with extension sagittal oblique (ESO) MR images with regard to delineation of the anterior cruciate ligament (ACL) in the knee. DESIGN: To establish the appropriate degree of flexion of the knee joint, two human cadaveric knee joints were used as a supplementary technique. FS and ESO images then were performed in 17 knees with an intact ACL and six knees with a torn ACL. In 22 of the 23 knees in which the MR diagnosis of intact or torn ACL corresponded to that derived from arthroscopy, the paired MR images were rated by a three-point scale. RESULTS: FS images were rated superior to ESO images in 53%, 41% and 47% of cases with regard to femoral attachment sites, midportions and tibial attachment sites of intact ACLs, respectively. FS images allowed better assessment of disrupted ACLs and residual ligamentous structures. Overall the FS images were either equal to or better than the ESO in the majority of cases. CONCLUSION: FS images are useful when the ACL is not well visualized in initial ESO images.
Although the diagnosis of infection is only a small part of the orthopedist's job description, it is a important part. This article discusses the fundamentals of orthopedic infections and highlights the refinements on this topic from a radiologic perspective. In addition to reviewing the imaging appearance of musculoskeletal infections in bone and the surrounding soft tissues, we focus on the advantages and disadvantages of five imaging methods: radiography, sonography, CT, scintigraphy, and MR imaging. Finally, we review three specific situations that have garnered substantial attention in recent medical literature: chronic recurrent multifocal osteomyelitis, musculoskeletal infections in AIDS patients, and pedal infections in diabetic patients.
RATIONALE AND OBJECTIVES: Compartmental anatomy of the forearm is complex and controversial. The purpose of this investigation was to demonstrate via magnetic resonance the anatomy of forearm compartments and their preferential ways of communication in a human cadaveric model. METHODS: Twelve forearm spaces (11 muscles and one intermuscular) were injected with a solution containing gadopentetate dimeglumine. The extent and distribution of leakage were evaluated on axial fat-suppressed T1-weighted spin-echo images. The findings were related to known descriptions of compartmental anatomy of the forearm. RESULTS: Contrast leakage occurred mostly into the intermuscular space and into the muscles adjacent to the injected muscle. A frank communication within the classically described three forearm compartments (volar, radial, and dorsal) was not present. The interosseous membrane was not an absolute barrier between flexor and extensor compartments. CONCLUSION: The classic description of three forearm compartments may not be sufficient to explain distribution of soft tissue abnormalities.
RATIONALE AND OBJECTIVES: The authors study the distribution of elbow joint fluid with flexion and extension of the joint and evaluate the imaging implications of such distribution. METHODS: Three cadaveric elbows were studied with radiography, ultrasonography, and magnetic resonance imaging after the incremental injections of 1 to 15 mL of saline solution into the elbow joint. Imaging was obtained with full flexion and extension of the joint. Anatomic sections were obtained for correlation. RESULTS: In flexion fluid initially collected posteriorly and, with larger quantities, anteriorly. In extension the anterior fat pad was pressed into its fossa and the posterior fat pad was displaced superiorly by the olecranon process. On lateral radiographs in elbow flexion a positive fat pad sign was seen with 5 to 10 mL of fluid in the joint. Sonography allowed identification of 1 to 3 mL of fluid posteriorly with the elbow flexed. Magnetic resonance imaging allowed identification of 1 mL of fluid, regardless of joint position and location. CONCLUSIONS: The distribution of joint fluid in the elbow is influenced by flexion and extension of the joint. Radiography is best performed in flexion. Sonography is more sensitive than radiography in diagnosing effusions, but should be performed along the olecranon fossa with the elbow flexed. Magnetic resonance imaging is most sensitive in identifying effusions, regardless of joint position or location.
RATIONALE AND OBJECTIVES: The authors evaluate the functional changes in patients with cervical radiculopathy and increasing symptoms after provocative maneuvers at flexion, extension, axial rotation, and coupled motions of the cervical spine. METHODS: Twenty-one patients with cervical disc herniation (n = 17) or cervical spondylosis (n = 4) in whom symptoms were elicited at flexion, extension, axial rotation, and coupled motions of the cervical spine were studied. The patients were examined inside a positioning device by using a circular surface coil for signal reception. At neutral position (0 degrees) and at provocative positions sagittal T2-weighted turbo spin-echo, axial T2-weighted two-dimensional flash sequence, sagittal three-dimensional (3D) fast imaging with steady state precision sequence and coronal 3D double-echo-in-the-steady-state sequences were obtained. The 3D sequences were reformatted in the axial and oblique coronal planes perpendicular to the exiting nerve roots. The images were evaluated for the size of disc herniations, the foraminal size and cervical cord rotation or displacement at provocative position compared with neutral position (0 degrees). RESULTS: Compared with neutral position (0 degrees), change in size of disc herniation was not found in any (0%) of the provocative positions. In five (24%) patients cervical cord rotation or displacement was noted at axial rotation. The foraminal size increased at flexion, axial rotation to the opposite side of pain and flexion combined with axial rotation to the opposite side of the pain. The foraminal size decreased at extension combined with axial rotation to the side of the pain. A decrease or no change in foraminal size was observed at either extension or axial rotation to the side of the pain. CONCLUSIONS: In patients with cervical disc herniation or cervical spondylosis, exacerbated pain at defined provocative maneuvers is related more to changes in the foraminal size and to nerve root motion with, in some cases, cervical cord rotation or displacement than to changes in the size of herniated discs.
RATIONALE AND OBJECTIVES: The authors assessed the ability of a low-field-strength extremity-only magnet to provide visualization of the triangular fibrocartilage and the scapholunate and lunotriquetral ligaments. METHODS: Twelve human wrists were examined with a 0.2 T extremity-only magnet. T1-weighted spin echo, proton density-weighted, and T2-weighted turbo spin echo, short-tau inversion recovery, and three-dimensional gradient recalled echo images were acquired, and sections of the specimens were then made that corresponded to the magnetic resonance images. Masked imaging analyses were correlated with macroscopic and limited histopathologic findings. RESULTS: Low-field-strength extremity-only magnet allowed consistent visualization of the triangular fibrocartilage and accurate assessment of a small number of complete tears of the triangular fibrocartilage. The scapholunate ligaments in all cases were identified using a combination of imaging sequences. Consistent visualization of the lunotriquetral ligament with a low-field-strength extremity magnet was difficult. CONCLUSIONS: Magnetic resonance imaging with a low-field-strength extremity-only magnet can be used to visualize the triangular fibrocartilage and the scapholunate ligament, but not the lunotriquetral ligament.
PURPOSE: To evaluate the cross-sectional imaging features of osteochondral defects (OCDs) of the glenoid fossa and to elicit a more detailed analysis of the trauma, if any, that may cause this injury. MATERIALS AND METHODS: Eight patients (seven male patients, one female patient; age range, 15-42 years; mean age, 27 years) with an OCD in the glenoid fossa were identified. Conventional computed tomography (CT), CT arthrography, or magnetic resonance (MR) imaging was performed. Surgical correlation was available in six patients. RESULTS: Six patients had a history of anterior dislocation or subluxation, one patient had an acromioclavicular joint separation, and one patient had chronic pain. Seven patients had anterior labral tears, and four had a redundant capsular insertion. A glenoid OCD appeared as either a multiloculated cyst in the subchondral bone mimicking a subchondral cyst (six patients) or a single osteochondral fragment (two patients). The lesion ranged from 8 mm to 2.0 cm in diameter. Three patients had an intraarticular body. Surgery confirmed an OCD in six of six patients. CONCLUSION: A glenoid OCD occurs most often as a result of acute trauma and has a high association with instability, labral tear, and intraarticular bodies.
PURPOSE: To compare magnetic resonance (MR) arthrography with conventional arthrography and standard MR imaging in the evaluation of gamekeeper thumb. MATERIALS AND METHODS: Eighteen cadaveric thumbs with (n = 12) or without (n = 6) experimental abduction stress were examined with conventional arthrography, standard MR imaging, and MR arthrography. Standard MR imaging and MR arthrography were performed with 0.2-T (low-field-strength) extremity-only and 1.5-T (high-field-strength) magnets. Results of blinded imaging analyses were correlated with pathologic findings. Paired MR images and MR arthrograms were rated with a three-point scale. RESULTS: Fourteen ulnar collateral ligaments were torn, including eight nondisplaced (57%) and six displaced (43%) tears. For the presence of tear, diagnostic accuracy of conventional arthrography, low-field-strength MR imaging, high-field-strength MR imaging, low-field-strength MR arthrography, and high-field-strength MR arthrography was 83%, 89%, 90%, 94%, and 100%, respectively. With regard to displacement of the torn ligament, diagnostic accuracy was 61%, 89%, 90%, 94%, and 100%, respectively. MR arthrograms were rated superior to standard MR images in 72% and 90% of specimens with low-field-strength and high-field-strength magnets, respectively. CONCLUSION: Of the tested methods, MR arthrography proved to be the most sensitive to the diagnosis of a torn ulnar collateral ligament of the first metacarpophalangeal joint and of displacement of the torn ligament.
PURPOSE: To define the magnetic resonance (MR) imaging appearance of a hip effusion. MATERIALS AND METHODS: Fifty-two asymptomatic hips in 26 volunteers aged 20-37 years and five fractured hips were imaged at 1.5 T with T2-weighting in three planes. Images were computer digitized and analyzed for hip fluid volume and visually assessed for the presence and width of fluid pockets (in millimeters) seen in the acetabular notch; recesses anterior, posterior, and lateral to the femoral head; and recesses anterior, posterior, and medial to the femoral neck. Cadaveric hips were also injected with graduated amounts of saline (1-20 mL), and sequential MR and ultrasound images were obtained. RESULTS: Computer analysis yielded an average fluid volume of 2.7 mL (range, 0.7-5.6 mL) in asymptomatic and 6.1 mL (range, 1.7-11.6 mL) in symptomatic hips. The mean difference between the right and left hips was 0.8 mL (range, 0.0-2.9 mL). Discrete fluid pockets, sometimes measuring greater than 5 mm in width, were commonly seen in asymptomatic hips. Distention of the capsule by at least 5 mm along the length of the femoral neck was almost always seen after injection of 5 mL of saline and was consistently seen after injection of 10 mL of saline into cadaveric hips. CONCLUSION: Fluid adjacent to the entire length of the femoral neck, measuring at least 5 mm in width, is compatible with a joint effusion.
PURPOSE: To assess a low-field-strength extremity-only magnet in the evaluation of patellar cartilage abnormalities. MATERIALS AND METHODS: Four regions in each of 10 patellae from cadavers were examined in the transaxial plane with a 0.2-T extremity-only magnet and the following sequences: T1-weighted spin echo, proton density- and T2-weighted turbo spin echo, short inversion time inversion recovery, and two- and three-dimensional gradient echo with and without magnetization transfer contrast subtraction. Lesions depicted with MR imaging and seen in anatomic sections of the patellae were classified according to a modified standardized arthroscopic grading system. MR imaging and pathologic correlation was then analyzed. RESULTS: On the basis of macroscopic findings, 14 of 40 cartilage regions were found to be intact, grade 2A lesions were present in eight regions, grade 2B lesions in eight, and grade 3 lesions in 10. For the various MR imaging techniques, sensitivity was 25%-62% for grade 2A lesions, 50%-75% for grade 2B lesions, and 60%-90% for grade 3 lesions. Specificity was 81%-97% for grades 2A and 2B lesions, and 80%-97% for grade 3 lesions. Accuracy was 75%-82% for grade 2A lesions, 75%-92% for grade 2B lesions, and 80%-92% for grade 3 lesions. CONCLUSION: High-grade cartilaginous lesions can be evaluated reliably with low-field-strength MR imaging by using a combination of imaging sequences.