The relationship of computed tomography, gray-scale ultrasonography and radionuclide imaging in the evaluation of hepatic masses.

Hepatic scintigraphy, gray-scale ultrasonography, and computed tomography have proven to be useful in the initial detection and evaluation of hepatic masses. These studies appear to be complimentary since each provides information not available from the others. Hepatic scintigraphy is currently the method of choice for the initial evaluation of the liver for mass lesions as it is easily performed, relatively inexpensive, and affords detectability of intrahepatic mass lesions at least as great as that of ultrasonography or computed tomography. When a definite or suspected abnormality is seen by hepatic scintigraphy, computed tomography or ultrasonography may be helpful in providing better anatomic definition or clarification of the nature of the abnormality. The choice between these latter two modalities depends on the type of scanning equipment available and the observer's experience with each method.

DentaScan: a new diagnostic method for evaluating mandibular and maxillary pathology.

Although computerized tomography (CT) is valuable for evaluating head and neck pathology, it can be suboptimal when evaluating the presence or extent of mandibular and maxillary involvement by tumor, infection, or other pathology. The presence of dental restoration artifact, CT gantry positioning problems, and the inability to obtain cross-sectional images will diminish the accuracy of standard CT images. A program, termed either DentaScan or multiplanar reformation (CT/MPR), eliminates these problems by processing axial CT scan information to obtain true cross-sectional images and panoramic views of the mandible and maxilla. In this study, DentaScan imagery was used in 26 patients whose mandibles or maxillas were affected by tumor, osteomyelitis, or other pathology. CT scanning with multiplanar reformation proved useful in the precise location, assessment, monitoring, and treatment of various pathologies of the mandible and maxilla. Selected case studies illustrate the therapeutic implications and advantages of this new imaging technique.

Radiologic evaluation of aortic dissection.

The radiologic assessment of patients suspected of having an aortic dissection must be based on an understanding of the treatment options and how these are to be employed in any clinical setting. The appropriate selection and timing of imaging studies is crucial. The diagnosis of dissection must be quickly confirmed, other diseases that mimic dissection must be excluded, and the type and extent of dissection must be established so that appropriate therapy can be instituted. Although computed tomography, magnetic resonance (MR) imaging, and echocardiography greatly enhanced the ability to evaluate the aorta by noninvasive means, aortography remains the examination of choice for defining the vascular anatomy, especially when surgical intervention is considered. MR imaging may become the primary examination for the initial and subsequent evaluation of acute and chronic dissections as MR angiographic techniques improve and changes are made in monitoring equipment to allow the safe examination of acutely ill patients.

Computed tomography of the abdomen: initial experience.

Computed tomography has provided a new dimension in the roentgenologic evaluation of the abdomen. Normal structures not visible on conventional examinations are clearly identified. Abnormalities are recognized by their alterations in anatomic form or by their effect on tissue absorption values. Our early experience suggests that in the abdomen computed tomography will be most valuable in detecting lesions in those sites least accessible to conventional roentgenographic methods such as the liver, spleen, pancreas and retroperitoneum.

Acute injury of the ligaments of the knee: magnetic resonance evaluation.

Eleven acutely injured knees and 13 normal knees were examined by magnetic resonance imaging (MRI) to assess the value of this modality in detecting acute ligamentous injury of the knee. The presence of torn ligaments in the injured knees was determined by arthroscopy and/or arthrotomy in ten cases and clinical follow-up in one case. The anterior and posterior cruciate ligaments (ACL and PCL) were demonstrated by sagittal spin echo (SE) images through the intercondylar notch (TE = 30 ms; TR = 2,000 ms). The tibial and fibular collateral ligaments (TCL and FCL) were evaluated on coronal SE images (TE = 30 ms, TR = 200 or 530 ms; TE = 120 ms, TR = 2,000 or 2,120 ms). The ACL and PCL were considered torn on MR if they appeared disrupted or were not seen in their normal anatomical positions. The collateral ligaments were considered torn if abnormal high-intensity signal was noted in adjacent soft tissues on TE = 120 ms images or if disruption of a ligament was apparent. Eleven of 15 torn ligaments and 80 of 81 normal ligaments were correctly identified by these criteria. It is concluded that MR imaging may be useful in detecting acute injury of ligaments of the knee.

Endometriosis simulating a soft tissue tumor of the thigh: CT and MR evaluation.

A histologically documented case of endometriosis within the deep musculature of the thigh is presented. Although occurrence of endometriosis outside the abdomen is rare, characteristic periodic exacerbation of symptoms at the time of menstruation should suggest the correct diagnosis.

Soft-tissue masses of the locomotor system: comparison of MR imaging with CT.

Magnetic resonance (MR) images and computed tomographic (CT) scans of histologically characterized soft-tissue masses of the locomotor system in 35 patients were compared for image contrast, demonstration of bone destruction, and display of extent and anatomic relationships of the masses. Subjective criteria for predicting malignancy were tested. T1 measurements were made in a few cases. Intensities of masses relative to those of fat and muscle in spin-echo T1-weighted and highly T2-weighted images were evaluated for correlation with tissue type. Subjective value of using coronal and sagittal images was assessed. Because of its superior inherent image contrast and its ability to provide direct sagittal and coronal images, MR was better than CT in demonstrating size and extent of most tumors and their relationships to vascular and nonvascular structures. However, bone destruction was more difficult to see with MR. Except for fatty tumors, MR was not helpful in identifying tissue type. Subjective criteria were of limited value in distinguishing benign from malignant lesions. Moreover, there is currently no credible evidence that T1 or T2 measurements are helpful in this regard. Study results suggest that MR is superior to CT in evaluating soft-tissue masses of the locomotor system. If an MR examination is performed, CT may not be necessary in certain cases unless bone involvement is suspected.

Contributions of computed tomography in the staging and management of malignant lymphoma.

Pretreatment staging is considered essential in the management of patients with malignant lymphoma, particularly nodular sclerosing Hodgkin disease. The results of CT examination of 33 patients with malignant lymphoma are correlated with the results of lymphangiography, nuclide images of the liver and spleen, gallium citrate57 images of lymphoid tissue, and nuclide bone images. CT is least effective in the early clinical stages of malignant lymphoma because normal or minimally enlarged nodes are difficult to detect; CT is probably reliable enough to replace lymphangiography of gallium57 imaging in patients with advanced disease.

Congenital hepatic artery aneurysm simulating pancreatic carcinoma.

The authors report a case of a hepatic artery aneurysm that simulated a mass in the head of the pancreas. The correct diagnosis was made preoperatively based on several findings: curvilinear calcification within the mass on CT, a well-defined cystic collection on ultrasound, absence of biliary duct dilatation or jaundice, and presence of other aneurysms.

Femoral capital osteonecrosis: MR finding of diffuse marrow abnormalities without focal lesions.

Six painful hips in five patients were examined with magnetic resonance (MR) imaging and were found to have diffuse signal abnormalities in the marrow of the femoral head and neck, which extended into the intertrochanteric area in five cases. The abnormal regions were low in signal intensity on images obtained with a short repetition time (TR) and a short echo time (TE) and were isointense or hyperintense on long TR/TE images--findings that have been attributed by others to bone marrow edema. Edema was also seen in marrow just above the acetabulum in two cases. No focal abnormalities characteristic of osteonecrosis were seen. Osteonecrosis was subsequently shown to be present in all six femoral heads at core biopsy (three cases) or by subsequent development of focal MR abnormalities reported to be highly specific for osteonecrosis (three cases). The affected hips had been radiographically normal or subtly osteopenic and had shown intense radionuclide uptake in the femoral head at scintigraphy, with lesser abnormality in the neck and intertrochanteric region. Follow-up MR examinations of five of the six femoral heads showed the diffuse abnormalities to have been transient. Although diffuse MR abnormalities in the proximal femur are not specific, they may indicate the presence of osteonecrosis of the femoral head.