Biomedical subjects
Publications and source records attributed to A Bonakdarpour.
Orthogonal sections usually suffice to demonstrate the soft tissues of the knees, but oblique MR sections may provide better images of the cruciate ligaments. The authors cite indications for oblique sections and discuss their production.
In six cases of giant cell tumor the magnetic resonance (MR) images obtained with various pulse sequences and field strengths were compared to the corresponding computed tomography (CT) scans and plain roentgenograms. MRI was superior to CT and plain films in demonstrating areas of tissue inhomogeneity within the tumor as well as soft tissue extension. CT was superior in demonstrating cortical thinning. Multiplanar imaging capability and visualization of articular cartilage may demonstrate intra-articular tumor spread. The characteristic MRI findings with short TR/TE (T1-weighting) and long TR/TE (T2-weighting) are described. We also describe one case where serial MR scans were used to assess response to therapy.
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Proximal femoral focal deficiency, an uncommon congenital anomaly, necessitates early radiologic classification for surgical planning and treatment. Objective radiographic criteria, including femoral length index, acetabular depth index, acetabular angle index, and shape of the proximal femur were determined in 49 patients before cartilaginous ossification of the femoral capital epiphysis; final classification was based on follow-up radiographs or findings at arthrography or surgery. These parameters were analyzed to determine the accuracy and contributions of each in classification. Correct classification into one of three groups was possible in 86% of cases with use of three of the parameters: femoral length index, acetabular depth index, and shape of the proximal femur. The acetabular angle was found to contribute insignificantly to classification. Magnetic resonance imaging, used in only one case, depicted the nonossified cartilaginous femoral capital epiphysis, thus obviating the need for invasive diagnostic procedures and facilitating early classification.
Twenty-one joints with stable (n = 9) or loose (n = 12) osteochondritis dissecans (OCD) lesions were examined in 15 subjects with plain radiography, three-phase bone scintigraphy, and magnetic resonance (MR) imaging. The lesion size and the thickness of the sclerotic margin as measured on plain radiographs were good parameters for predicting loosening. However, bone scintigraphy was more sensitive and specific in determining the mechanical stability of OCD lesions. MR imaging permitted direct visualization of loosening and fragment displacement; the latter permits differentiation of in situ loosening from a grossly unstable lesion. The noninvasive nature of bone scintigraphy and MR imaging makes them potentially preferable diagnostic modalities to arthrography for evaluating the mechanical status of OCD lesions.
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The subungual keratoacanthoma is a benign neoplasm which simulates and must be differentiated from squamous cell carcinoma. Subungual keratoacanthomas are rapidly growing tumors, causing bone destruction which usually heal spontaneously. The lesion most often presents as a painful, enlarging mass in middle-aged Caucasian patients. Radiographic examination demonstrates a lytic cup-shaped erosion of the underlying distal phalanx. It is essential to recognize keratoacanthoma and separate it from squamous cell carcinoma, both for prognostic and therapeutic reasons. We present two cases of proven subungual keratoacanthoma and discuss their radiographic and histologic characteristics, as well as the current treatment alternatives for this entity.
Forces and torques, due to a 0.3 Tesla magnetic field were evaluated on ten hip prostheses and ten hemostat clips. Measurements were performed with an instrument utilizing the movement of a laser beam caused by the deflection of a cantilever. The results indicate effects, if any, to be smaller than the instrument's sensitivity which, at its highest, was 7 mg of force and 125 mg.cm of torque.
Lumbar radiographs and scintigrams were compared in 24 patients with low back pain. Radiographs of the pars interarticularis were classified as type 0, normal; type 1, a stress fracture with an irregular lucent line in an area of sclerosis; type 2, an evolving or healed stress injury showing either sclerosis or narrowing; or type 3, a nonunited fracture with a large lucent defect and well defined margins. Radiographs and scintigrams were abnormal in 88% (21/24) and 54% (13/24) of patients, respectively. Scintigraphy was most often positive with type 1 (73% [11/15]) and negative with type 3 abnormalities (83% [10/12]). Findings suggest that in the proper clinical setting, identification of a type 1 abnormality is sufficient to diagnose acute pars injury. If a type 2 or 3 abnormality is present, scintigraphy is used to confirm recent injury. Finally, if no radiographic abnormality is present at the site of localized pain, scintigraphy should be used to exclude stress injury not radiographically apparent.
Giant synovial cysts (GSC) are large, well-defined cavities, containing synovial fluid and lined by a synovium-like membrane, which extend for a variable distance outside the joint cavity. We are reporting 15 cases of GSC of various joints. Rheumatoid arthritis is the most common disease process reported in association with GSC. We suggest that trauma may be a more important cause of GSC than has previously been described. Arthrography and ultrasonography are both helpful in diagnosing these large cysts, especially in the knee to aid in differentiating GSC from thrombophlebitis.
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A case of spinal cord compression secondary to an osteochondroma of the vertebral body of T-4 is reported. Computed tomography aided in the display of the lesion and the planning of its resection.
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Radiological findings in 75 cases of aneurysmal bone cyst were analyzed. Sixty-five per cent were primary or simple and 35% were secondary, the aneurysmal bone cyst being combined with other osseous lesions. A primary aneurysmal bone cyst can be diagnosed with a high degree of certainty, but only 20% of secondary forms had the radiological appearance of aneurysmal bone cyst; in the other 80% the associated lesion dominated the radiological picture, particularly when it was malignant. In the secondary form a small biopsy specimen may show the features of aneurysmal bone cyst only; without radiological assistance a concomitant malignant lesion may be missed. Therefore, there must be close collaboration between the radiologist and and the pathologist.
Intestinal ischemia was produced in dogs by ligation and division of a branch of the superior mesenteric artery that supplied a selected segment of bowel. The bowel lesions included patchy mucosal necrosis, ulceration, and stenosis. The development of these changes was studied, and it appeared that ulceration was accompanied by severe submucosal inflammation in uniform appearance. Healing was accomplished by regeneration of mucosa and widespread submucosal fibrosis. Villi developed in the regenerated mucosa about 30 days after the onset of ischemia. Focal disruption of muscularis mucosa and loss of ganglion cells were common, although muscularis propria remained largely intact.
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