Massive skeletal muscle invasion by lymphoma.

Three patients had diffuse enlargement of skeletal muscle of the thigh as the result of infiltration by diffuse large-cell lymphoma. One case presented de novo as diffuse lymphoma, but the other two had previous diagnoses of nodular lymphoma and Hodgkin's disease. Computed tomographic scanning disclosed an enhancing mass in the thigh with infiltration of skeletal muscle groups; abnormal medullary cavities were noted in the adjacent long bones. Muscle biopsy established the diagnosis in two of the patients.

[131I]iodocholesterol scintiscan and a rare "functional" black adenoma of the adrenal cortex.

A rare functional black adenoma (FBA) of the adrenal cortex was found to be the cause of hypertension and cushingold features in a 34-yr-old white female. Preoperative studies included [131I]iodocholesterol scanning (ICS) of the adrenal glands, which demonstrated the increased release of cortisol from the affected adrenal gland, with the failure of the opposite adrenal gland to record. This is evidence that cortisol was suppressing adrenocorticotropin (ACTH) output by the pituitary gland. This case documents the clinical utility of "functional" imaging techniques in this clinical setting.

Computed tomography in the evaluation of the patient with symptomatic abdominal aortic aneurysm.

Computed tomography was used to evaluate 25 hemodynamically stable patients with suspected leaking abdominal aortic aneurysms. Of 10 patients found to have the presence of free retroperitoneal blood, six underwent immediate operation and five survived (83%). Delay in operation uniformly resulted in death. There was one false-positive study. Twelve patients demonstrated no extravascular fluid on initial computed tomography interpretation. Unsuspected nonvascular problems were found in six patients (40%). There was one false-negative study that resulted in a death. Clinical findings at initial examinations were similar in both groups. We conclude that in the hemodynamically stable patient, combining prompt computed tomography evaluation and immediate operation optimizes outcome in patients with leaking abdominal aortic aneurysms.

Characterization of chest masses by FDG positron emission tomography.

Radiographic imaging techniques have proved to be of limited value in characterizing chest masses. Likewise, scintigraphic techniques with tumor-seeking single photon emitting agents have shown marginal practical benefit. In contrast, high resolution PET with [F-18]-2-fluoro-2-D-deoxyglucose (FDG) offers a unique opportunity to distinguish benign from malignant processes by determining metabolic characteristics. PET scan results, including graphical analysis of tumor transfer constants (Patlak plot) in 21 patients with primary lung cancer, were compared to clinical outcome (histologic proof or clinical follow-up of longer than 1 year) in 54 patients who had chest masses identified by CT and/or plain film. The patients were categorized into three groups. The first group (N = 23) had primary, unknown, lung masses. Differentiation of benign from malignant tumors by PET had a sensitivity of 100% and a specificity of 67%. The second group (N = 13) had proven lung carcinoma or lymphoma and post-therapy PET scanning for recurrent tumor. In this setting, PET had a sensitivity of 83% and a specificity of 80%. The third group (N = 18) had extrathoracic malignancies and suspected pulmonary metastases. Metastatic lesions were identified with a sensitivity of 87% and specificity of 83%. Glucose uptake by normal tissue is variable and inflammatory/infectious processes can have high FDG uptake and overlap with the glucose uptake of malignant tissue. FDG PET is useful in characterizing chest tumors based on the level of their metabolic activity. Malignant tissue has a high glucose uptake. Elevated FDG uptake by an active inflammatory process may produce overlapping results.(ABSTRACT TRUNCATED AT 250 WORDS)

Differentiating benign from malignant lung lesions using "quantitative" parameters of FDG PET images.

UNLABELLED: Fluorine-18 labeled deoxyglucose positron-emission tomography (FDG-PET) applications in oncology include the differential diagnosis of chest masses and single pulmonary nodules. However, FDG is not tumor-specific; rather, it also accumulates in inflammatory processes. This study was performed to identify image parameters that would improve the specificity of PET. METHODS: Twenty-six patients who had benign and malignant lung lesions were examined retrospectively. Positron-emission tomography data were acquired in dynamic scanning mode after intravenous bolus of 250-402 MBq of FDG. Standardized uptake values (SUVs) were calculated and Patlak analyses were performed in selected regions of interest in the PET images. Positron-emission tomography results were related to histological diagnosis (N = 49) or clinical follow-up (N = 3). RESULTS: The specificity and sensitivity of the original PET scan reports, which was based on visual image interpretation and loosely applied SUVs, was 100% and 73%, respectively. Using the SUVs with a cut-off value of 3.8 and Kpat value with a cut-off at 0.025 min-1 improved the specificity to 81% and 85%. CONCLUSION: FDG-PET image interpretation can be facilitated by using SUV information or the accumulation rate of the radiotracer (Patlak). With additional validation, this method could have a significant cost-effective impact on the medical/surgical management of chest masses.

Predictability of splenic salvage by computed tomography.

The recognition of overwhelming post-splenectomy infection (OPSI) has led to greater efforts to conserve splenic tissue in patients sustaining blunt torso trauma. Nonoperative management of splenic trauma has emerged as a means to enhance splenic salvage yet criteria to assure the safety of such an approach remain ill defined and controversial. Since severity of injury directly influences outcome, a need exists for identification of splenic injuries that require early operation and repair or removal. Using our recently reported classification of splenic trauma, 46 patients with blunt splenic trauma were evaluated preoperatively with computed tomography (CT). Injuries were graded I through IV and were described as capsular or subcapsular disruptions without parenchymal injury (four); capsular and parenchymal injuries not involving the major vessels or hilum (24); injuries involving major vessels and/or the hilum (17); and fragmentation/devascularizing injuries (one). Additional modifiers were added for associated intra-abdominal and/or extra-abdominal injuries. Sixteen patients had their splenic injuries managed nonoperatively and the remainder underwent operation for the splenic injury or associated injuries. The CT classification was confirmed in all patients and we believe early operation optimized splenic salvage. We conclude that: 1) CT is an accurate technique to determine the extent of splenic injury; 2) CT classification of splenic trauma has a high correlation with anatomic findings and need for operation; 3) early operation in patients with severe class II and all class III injuries affords optimal conditions for splenic salvage; and 4) early definitive management of splenic trauma significantly reduces late splenectomy and shortens hospitalization.

Identification of a bronchopleural fistula by computerized tomography--a case report.

A case report is presented of a bronchopleural fistula demonstrated on computed tomography (CT) scan but not identifiable on plain radiographs. The case illustrates the importance of CT in evaluating the pleural space.

Lymphatic changes in retroperitoneal lipomatosis.

Retroperitoneal lipomatosis is a condition in which excessive fat deposits in the retroperitoneum can exert a mass effect, with displacement of normal structures. In the case presented, it displaced lymph nodes and simulated adenopathy in nonopacified nodes. The specific diagnosis of retroperitoneal lipomatosis as the cause of the mass effect can be made by computerized tomography.

Mirizzi syndrome simulating a tumor by ERC.

ERC was initially performed on a patient with right upper quadrant pain and jaundice. The filling defect in the CHD was felt to be a tumor. A correct preoperative diagnosis of Mirizzi's syndrome was made by CT.

Calcified bronchopulmonary sequestration.

An unusual case of calcified sequestration in a 76-year-old female is presented.

Assessment of primary and metastatic ovarian cancer by positron emission tomography (PET) using 2-[18F]deoxyglucose (2-[18F]FDG).

The potential of positron emission tomography (PET) to distinguish benign from malignant ovarian tissue was evaluated by comparing the results of F-18 fluoro-2-D-deoxyglucose (F-18-FDG) PET scans with computed tomography and surgical findings. If sufficiently sensitive, this method might play a role in localizing metabolically active tumor sites for diagnosis, staging, and follow-up of ovarian cancer. Fifty-one patients had imaging studies prior to laparotomy for suspected ovarian cancer. PET scans were done with an ECAT 931-08-12 or ECAT EXACT (Model 921, Siemens/CTI, Knoxville, TN) after iv injection of 185-370 MBq of F-18-FDG. (ECAT is a trade name for "emission computerized axial tomograph.") Data were acquired in dynamic scanning mode and time activity curves (TACs) were evaluated in multiple regions of interest identified by visual interpretation of the PET scans. Scan interpretation, standardized uptake values, and TAC profiles were related to surgical and histological findings. The results of this pilot study show good correlation between PET and histological findings. The positive predictive value of PET for ovarian cancer was 86% and, perhaps more important, the negative predictive value was 76%. This early work indicates that PET may be useful in the management of patients with ovarian neoplasms by identifying occult foci of metabolically active tumor that do not appear on morphological studies.

Hemorrhagic angiomyolipoma: demonstration by computed tomography.

Preoperative tissue specific diagnosis of renal angiomyolipomas is now frequently made by computed tomography (CT). Although hemorrhage of these hypervascular tumors is a common cause for presentation, it is rarely recognized preoperatively. We present two cases of large, solitary angiomyolipoma complicated by perinephric and intratumoral hemorrhage demonstrated by CT.

Bladder pheochromocytoma with ring calcification.

A case of a 19-year-old male with a paraganglioma (pheochromocytoma) arising in the prostate and involving the urinary bladder is presented. The radiological studies, including computed tomography, demonstrated ringlike calcification of the tumor, a rare finding that is highly suggestive of the diagnosis of pheochromocytoma. The tumor was excised and found to be malignant at surgery.