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Biomedical subjects

A Shirkhoda

Publications and source records attributed to A Shirkhoda.

At least 73 records · Page 4Linked to original sources

Computed tomography of acetabular fractures.

Computed tomography (CT) is helpful in delineating the extent and configuration of fractures of the acetabulum. These injuries are frequently complex, and the precise pathological anatomy is not easily demonstrated by conventional radiographs. In some cases CT will reveal a fracture which may not be seen on the radiograph. In addition, the extent of soft-tissue damage and joint involvement is precisely demonstrated with CT. Five cases are presented to illustrate the value of CT in acetabular fractures.

Acetabulum↗

Renal lymphoma imaged by ultrasound and gallium-67.

Lymphomatous involvement of the kidneys, usually a secondary process, may be seen as single or multiple sonolucent or weakly echogenic masses on ultrasound. The majority of these patients have a known diagnosis of lymphoma and are being evaluated for change in nodal mass size, flank pain, and/or deteriorating renal function. Occasionally, these masses are discovered on an excretory urogram and are further investigated with ultrasound. The ultrasound findings may be confirmed with gallium scanning. Five such cases are presented along with the ultrasonic and gallium scan findings.

Adult↗

Technical note. Optimal computed tomography technique for bone evaluation.

Various combinations of window settings and displays were evaluated to determine the optimal photographic reproduction of images obtained from the Ohio-Nuclear Delta scanner to best demonstrate bony structure by computed tomography. A combination of wide window and negative images will produce better bony structure detail than various other settings. The physical basis of this technique will be described along with several cases to illustrate the conclusion. Although no one combination was universally adequate, the best in our experience was a wide window with negative images.

Adolescent↗

Iatrogenic superior vena cava syndrome with spontaneous improvement.

We describe a patient in whom superior vena cava syndrome developed after central venous catheterization and infusion of caustic medications. The diagnosis was proven by venography. Because anticoagulant therapy was contraindicated, the patient was clinically observed and the syndrome improved spontaneously. Follow-up venographic examination was normal.

Catheterization↗

Adult polycystic kidney disease: ultrasonographic and computed tomographic appearance.

Sixteen patients with adult polycystic kidney disease (PKD) were studied by gray scale B mode ultrasonography. The nephrosonographic appearance of adult PKD is a spectrum ranging from kidneys of normal size to enlarged kidneys with multiple variable-sized cysts. Strong focal cortical echoes were present in patients with only small cysts in the renal cortex. Hepatic cysts, which appeared as sharply marginated anechoic regions within the liver parenchyma, were detected by ultrasound in 50% of our patients. Hepatic and renal cysts appeared on computed tomograms as sharply defined, ovoid areas of low attenuation. There was good diagnostic correlation between ultrasonography and computed tomograms as sharply defined, ovoid areas of low attenuation. There was good diagnostic correlation between ultrasonography and computed tomography. Ultrasound and computed tomography are accurate methods for diagnosis of adult PKD; however, the ability to diagnose quickly and noninvasively both renal involvement and associated extrarenal involvement makes ultrasound the procedure of choice for diagnosis, screening, and followup.

Adult↗

Computerized tomography of frontal sinus pneumatocele.

The radiographic feature and computerized tomography (CT) findings in a case of frontal sinus osteoma associated with pneumatocele are described along with the clinical history and surgical findings. CT gives useful information regarding the extent of air dissection and its relation with the ventricular system.

Adult↗

Symptomatic osseous sarcoidosis with findings on bone scan.

Twenty-one years after the onset of sarcoidosis, a 51-year-old woman experienced pain in the lower portion of her back, which proved to be the result of sarcoidosis involving the pelvis. The pelvic abnormality consisted of osteosclerotic and osteoblastic lesions. A bone scan showed several other areas of increased uptake, and the diagnosis was confirmed by bone biopsy. The patient improved with treatment with steroids, but the findings on the x-ray film and the bone scan did not change. Sarcoidosis may cause obscure, but symptomatic, osseous lesions.

Adult↗

Diagnosis of leukemic relapse in the pelvic soft tissues of juvenile females.

Five females with childhood acute lymphocytic leukemia whose disease relapsed in the pelvis were studied. In all five patients, relapse occurred late in the disease process, and all patients had been in complete continuous remission before relapse. Intravenous pyelogram and barium enema revealed hydronephrosis or a mass effect on the bladder or rectosigmoid colon. In three patients, sonography established the presence of a clinically palpable mass with involvement of the uterus, ovaries, and pelvic side walls. In one patient there was infiltration of the bladder and in another, infiltration of the appendix, both confirmed by biopsy.

Biopsy↗

MR imaging of myositis ossificans: variable patterns at different stages.

Five patients with a palpable mass at presentation underwent magnetic resonance (MR) imaging. The final diagnosis was myositis ossificans (MO). MR imaging features, particularly after injection of gadopentetate dimeglumine, mimicked those of an inflammatory mass or neoplasm. The lesions were excised in three patients, and the images were correlated with histologic findings. Three different appearances were noted on MR images, corresponding to the stages of maturation of MO. Two cases involved early-stage lesions, and T1-weighted MR images showed a mass with homogeneous intermediate signal intensity. Both lesions showed rim enhancement after contrast agent injection and high signal intensity on T2-weighted images. Pathologic specimens demonstrated stroma with masses of spindle cells in which osteoid production was interspersed. The enhanced rim of the lesion mimicked the expected MR appearance of an abscess or necrotic tumor. Areas of enhancement in adjacent muscle were also seen on postcontrast T1-weighted images. Intermediate-stage MO was present in one case; there was evidence of a thin rim of calcification on plain radiographs and fatty changes in the lesion on T1-weighted images, corresponding with histologic findings. One case of a mature lesion showed a considerable degree of peripheral calcification both on MR images and at histology. MR imaging is nonspecific in the diagnosis of early-stage MO.

Abscess↗

Giant cell tumor of the tendon sheath in the ankle: MRI with pathologic correlation.

We report a case of Giant cell tumor of the tendon sheath involving the ankle, wherein spin-echo (T1- and T2-weighted), gradient-echo, and dynamic contrast-enhanced sequences were performed, and the tumor was noted to be very vascular. To the best of our knowledge, the use of gradient-echo sequences and the pattern of enhancement by time-intensity curves has not been reported earlier.

Adult↗

Gradient-echo perfusion imaging of musculoskeletal abnormalities with contrast-enhanced two-dimensional fat-saturation FLASH.

The objective of this study was to evaluate the utility of MR perfusion imaging of various musculoskeletal lesions with a contrast-enhanced two-dimensional fat saturation fast low angle shot (FLASH) sequence and to assess the potential of this technique for distinguishing malignant from benign conditions. Thirty-six musculoskeletal lesions were studied at 1.5 T. The signal intensity of the lesions, adjacent artery, muscle, bone marrow, and fat were plotted against time. The time to peak enhancement, time to maximum signal intensity, percent enhancement, rate of peak enhancement, and rate of enhancement parameters were calculated. Because of a significant overlap between malignant and benign conditions, accuracy rates were lower than reported previously. The best parameter based on these values was the rate of peak enhancement (sensitivity, 84.6%; specificity, 65.2-66.6%; positive predictive value, 57.8-68.7%). Fat saturation gradient-echo MR perfusion imaging allows for a rapid assessment of the vascularity of musculoskeletal pathology; however, a significant overlap persists between malignant neoplasms and several benign conditions.

Adipose Tissue↗

Contrast-enhanced 3D MRA with centric ordering in k space: a preliminary clinical experience in imaging the abdominal aorta and renal and peripheral arterial vasculature.

The objective of this study was to determine the clinical utility of a contrast-enhanced, centric reordered, three-dimensional (3D) MR angiography (MRA) pulse sequence in imaging the abdominal aorta and renal and peripheral lower extremity arteries. Twenty-eight MRA studies were performed on 23 patients and four volunteers at 1.5 T using a 3D contrast-enhanced, centric reordered pulse sequence. In 20 patients, the abdominal aorta and renal arteries were imaged, and in seven patients, the lower extremity arteries were imaged. In 19 patients, a total of 51 renal vessels were evaluated (33 renal arteries using .1 mmol/kg of gadopentetate dimeglumine and 18 renal arteries using .2 mmol/kg of gadoteridol). A total of 70 peripheral arterial segments were assessed using .2 mmol/kg of gadoteridol. Correlation with conventional angiography was made for the following 14 cases: renal artery stenosis (four cases), abdominal aortic stenosis (one case), arteriovenous fistula in a transplant kidney (one case), renal arteriovenous malformation (one case), common iliac artery aneurysms (one case), and peripheral lower extremity (six cases). Of the 70 peripheral arterial segments evaluated, in 35, there was correlation with x-ray angiography. The mean percent of aortic signal enhancement was significantly higher in the .2 mmol/kg dose group (370.8 +/- 190.3) than in the .1 mmol/kg dose group (184.5 +/- 128.9) (P = .02). However, there was no apparent difference between the two doses for visualization of the renal and accessory renal arteries. There was concordance between the contrast-enhanced 3D MRA studies and conventional angiography in all cases of renal artery and peripheral arterial stenoses and occlusions, including visualization of reconstituted peripheral arterial segments. There was no evidence of spin dephasing effects at sites of stenoses on the 3D contrast-enhanced MRA studies. Contrast-enhanced, centric reordered, 3D MRA can rapidly image the abdominal aorta and renal and accessory renal arteries, as well as peripheral lower extremity arteries, with high resolution. Accurate depiction of the vascular lumen at sites of stenosis is made because of the lack of spin dephasing effects, even with hemodynamically significant stenoses. Additional larger clinical trials are required with this promising technique.

Adult↗

Imaging features of splenic epidermoid cyst with pathologic correlation.

The spleen can be involved in a variety of cystic lesions ranging from cystic neoplasms and parasitic cysts to "true" and "false" cysts. Epidermoid splenic cyst is a rare true cyst that is developmental in origin. We present two young patients with such a cyst and illustrate their features on ultrasound, CT, and MRI with pathologic correlation.

Adult↗

Hepatic focal nodular hyperplasia: CT and sonographic spectrum.

Fifteen patients with pathologically proven focal nodular hyperplasia (FNH) of the liver had abdominal computed tomography (CT) (15) and ultrasound (11). In seven patients, the lesions were incidentally found during gallbladder or renal examination, whereas the other eight had a primary neoplasm and the liver was studied for possible metastasis. In 11 unenhanced CT scans, the ratio of isodense to hypodense lesions was 8 to 3. In 15 contrast-enhanced CT scans, seven were isodense, six were hypodense, and in two, the lesion enhanced (hyperdense). In seven patients a hypodense lesion on unenhanced CT became isodense with contrast injection. Delayed images in three showed the lesions appearing as hypodense in two and displaying a rim of enhancement in one. In one case, unenhanced CT was normal and only enhanced CT showed an area of homogeneous increased density. Ultrasound was done in 11 patients, the lesion was hypoechoic to the liver in five, echogenic in four, and isoechoic in two. Findings of central scar were seen on CT and ultrasound in three cases. Pathologic diagnosis was available in all cases, seven by needle aspiration and eight by surgical resection. In our experience, FNH has many CT and sonographic features that can mimic hemangioma or metastasis. While the presence of a central scar increases the specificity, in a cancer patient, the findings should be interpreted with caution and needle aspiration should be obtained.

Adult↗