Preoperative evaluation of patients with primary hyperparathyroidism: role of high-resolution ultrasound.

Unilateral parathyroid exploration with adenoma removal and identification of a normal parathyroid gland is an accepted surgical approach for the treatment of patients with primary hyperparathyroidism. This study prospectively evaluated the ability of high-resolution sonography to localize adenomas preoperatively and the effect of this localization on operative time and cost in 37 previously untreated patients undergoing surgical treatment for primary hyperparathyroidism. The sensitivity and positive predictive value of the sonographic examination were 84% and 90%, respectively. A true positive sonographic examination decreased surgical time by an average of 40 minutes and reduced operative charges by $564, including the cost of the test ($156). In experienced hands high-resolution sonography can be a cost-effective means of localizing parathyroid adenomas where unilateral exploration is considered an accepted surgical approach.

Diagnosis of diaphragmatic trauma with helical CT in a swine model.

OBJECTIVE: The purpose of this study was to determine whether diaphragmatic injury can be accurately diagnosed with helical CT in a swine model. The hypothesis of our study was that thin-section helical CT with sagittal and coronal reformations can reliably detect injury of the diaphragm. MATERIALS AND METHODS: The study was performed in a swine model because of the similarity of the swine thorax to the human thorax. Ten swine had a limited abdominal helical CT (enteral contrast; 3-mm collimation; pitch, 1) before and after surgical creation of a 6-cm posterolateral laceration in the left hemidiaphragm. A repeat scan was obtained after 5 cm of gastric fundus was sutured through the laceration. The gastric fundus was used because it is the most commonly herniated viscus in human diaphragmatic injury. No IV contrast was used. Control, laceration, and herniation scans were reconstructed with 1.0-mm overlap and reformated in axial, sagittal, and coronal planes. Three observers scored each reformation as control or injury (defined as laceration or herniation) in a blinded and randomized fashion. RESULTS: Using helical CT, the observers were able to distinguish diaphragmatic injury from controls (p < .0001). The sensitivity and specificity were 92% and 87%, respectively, for sagittal reformations; 85% and 87%, respectively, for coronal reformations; and 73% and 80%, respectively, for axial reformations. Sagittal reformations proved superior to coronal or axial reformations (p = .01). The results were independent of individual observers: We found no significant difference in accuracy among the three observers. CONCLUSION: Helical CT can accurately detect diaphragmatic injury in a swine model.

Aortoiliac disease: two-dimensional inflow MR angiography with lipid suppression.

A magnetic resonance (MR) imaging strategy, SLIP (spatially separated lipid presaturation), which can be incorporated into existing MR imaging and MR angiographic techniques, has been developed to suppress lipid signal. The authors report the clinical application of this technique, with a triple comparison of two-dimensional inflow MR angiography, with and without SLIP, and x-ray angiography in patients with aortoiliac disease. SLIP improved visualization of arterial segments, with 50 of 63 (79%) arterial segments visualized versus 41 of 63 (65%) for non-SLIP MR angiography. The SLIP strategy aids in the depiction of slow or turbulent flow, because the lipid signal is suppressed while the intravascular signal is left undisturbed. Image quality improves because of the combination of decreased background lipid signal intensity and use of the maximum-intensity-projection algorithm. Compared with x-ray arteriography, non-SLIP MR angiography had a sensitivity and specificity of 60% and 56%, respectively, for detection of lesions with 50%-100% diameter reduction, while SLIP MR angiography had a sensitivity and specificity, respectively, of 53% and 67%.

Duplex assessment of the portal venous system.

The clinical applications of duplex ultrasound and color Doppler imaging in the evaluation of the portal venous system and hepatic vasculature are quite diverse and widespread. These include identification of portal vein thrombosis, portal venous hypertension, and hepatic veno-occlusive disease as well as a role in the preoperative and postoperative treatment of patients who are candidates for portosystemic shunts or for liver allografts. As technological improvements continue, the current applications will almost certainly be refined, with resultant improvements in sensitivity, specificities, and accuracy rates.

Duplex assessment of the splanchnic vasculature.

The role of duplex ultrasound and color Doppler imaging in the evaluation of patients with suspected splanchnic vasculature obstructive disease and chronic mesenteric ischemia is not clearly defined. In this report the examination technique, as well as normal and abnormal findings, is discussed. Limitations are also described.

Duplex evaluation of native renal vessels and renal allografts.

Duplex ultrasound and color duplex imaging are useful in evaluating the renal vasculature. Investigation of native renal vessels includes the diagnosis of renal artery stenosis and occlusion and renal vein thrombosis. The sonographic examination of renal allografts may detect vascular complications and peritransplant fluid collections, both of which may impair allograft function. In order to perform and interpret renal vascular sonography, knowledge of pertinent vascular anatomy and proper duplex technique is essential. Renal arterial and venous examination with gray-scale, Doppler, and color duplex imaging is reviewed, comparing their performance with other methods of assessing renal vessels when appropriate.

Peripheral arterial occlusive disease: prospective comparison of MR angiography and color duplex US with conventional angiography.

Conventional angiography, two-dimensional inflow magnetic resonance (MR) angiography, and color duplex ultrasound (US) were performed on 12 patients in a blinded, prospective study. The ability to grade arterial lesions and plan revascularization interventions were compared. Arterial lesions were categorized as nonsignificant (0%-49% diameter reduction) or significant (50%-100% diameter reduction). Determination of nonsignificant and significant lesions with MR angiography was in agreement with that at conventional angiography in 100 of 140 lesions (71%). Agreement between results of conventional angiography and color duplex US occurred with 114 of 123 infrainguinal lesions (93%). Twenty-one vascular interventions were planned by using conventional angiography; there was agreement with color duplex US in 11 cases and MR angiography in five. Color duplex US performed well in the assessment of infrainguinal disease but was limited in the evaluation of iliac segments because of nonvisualization. The iliac region was visualized in more patients with MR angiography than with color duplex US, but image quality with MR angiography was inconsistent. Strategies to improve MR angiography of the peripheral vasculature merit further study.

Renal artery stenosis: prospective evaluation of diagnosis with color duplex US compared with angiography. Work in progress.

A prospective, double-blind comparison of color duplex sonography with angiography was performed for diagnosing renal artery stenosis in 50 kidneys in 26 patients. The major criterion for diagnosing a diameter narrowing of more than 50% was a velocity of greater than 100 cm/sec. Angiography demonstrated 10 stenoses and one occlusion in main or accessory renal arteries in seven patients. Twenty-two percent of kidneys had accessory renal arteries. Color duplex scanning helped identify 58% of the main arteries and no accessory vessels. None of the stenotic vessels were identified with duplex scanning, but the single occluded vessel was correctly diagnosed. Nine of the 29 vessels identified with duplex scanning were incorrectly diagnosed as stenotic, findings yielding a specificity of 37%. The authors conclude that the published velocity threshold of 100 cm/sec is too low. Duplex scanning with current technology is unlikely to prove satisfactory for screening patients with hypertension for renal artery stenosis.

The CT findings in pseudomembranous colitis.

The authors present their experience with the CT appearance of pseudomembranous colitis in 6 patients. In addition to the previously reported thickened colon wall, pericolonic inflammation was also noted in 5 of the patients.

Magnetic resonance imaging in recurrent carcinoma of the cervix.

Twenty patients with suspected recurrent cervical carcinoma were evaluated with computed tomography (CT) and high-field magnetic resonance imaging (MRI). Histological verification of the imaging findings were available in all cases. Computed tomography and MRI were equally effective in making the diagnosis of disease recurrence. The extent of vaginal recurrence and involvement of pelvic floor muscles was better shown on MRI than on CT.

Inhomogeneous enhancement of liver parenchyma secondary to passive congestion: contrast-enhanced CT.

Passive liver congestion secondary to increased hepatic venous pressure may accompany congestive heart failure. Abnormal patterns of hepatic parenchymal contrast medium enhancement in 25 patients with advanced congestive heart failure who were studied with computed tomography (CT) include a lobulated, patchy, inhomogeneous pattern in all 25 patients, an irregular perivascular enhancement in 14, and a global delay in parenchymal enhancement in nine. CT examinations showed cardiomegaly in the 20 patients with cardiac failure and pericardial effusion or thickening in the five patients with pericardial disease. Also noted were distention of the inferior vena cava (IVC) in 24 patients, hepatomegaly in 23, early reflux of contrast medium into the IVC in 21 and hepatic veins in 16, and hepatic perivascular lymph-edema in six. The abnormal patterns are thought to be due to slowing of hepatic blood flow. Confusion with Budd-Chiari syndrome and other forms of multifocal hepatic disease is avoidable with clinical and radiologic correlation.

CT and MR imaging in the evaluation of retroperitoneal fibrosis.

We have performed CT and MR on five patients with biopsy proven retroperitoneal fibrosis (RPF). Magnetic resonance (MR) accurately displayed a retroperitoneal mass of low signal intensity on T1-weighted scans and of heterogeneous medium signal intensity on T2-weighted scans. The coronal MR views demonstrated a retroperitoneal mass: the shape, signal intensity, and effects on the ureters and major vessels appear characteristic of RPF.

Preoperative evaluation of abdominal aortic aneurysm by MR imaging with aortography correlation.

Sonography, computed tomography, and most recently, magnetic resonance imaging (MRI) have been advocated as noninvasive imaging methods for the preoperative evaluation of patients with abdominal aortic aneurysms (AAA). We prospectively assessed the value of MRI in this clinical setting. Twenty of 23 patients with AAA referred for evaluation with biplane aortography underwent MRI within 3 days of aortography. MR and angiographic studies were interpreted prospectively and independently and then the results were compared with each other and with the operative findings. All angiographically demonstrated infrarenal and suprarenal aneurysms except one were documented as such by MRI. The distal extent of the aneurysm on MRI agreed with that on angiography in all but 3 cases. MRI is an accurate method for assessing the size and extent of AAA and its relationship to the main renal artery origins. MRI is not accurate in detecting vascular obstructions or accessory renal arteries. Therefore, the usefulness of MRI and the need for aortography in preoperative assessment of AAA depends upon the specific information the surgeon requires prior to aneurysmectomy in a given patient.

Differentiation between small benign and malignant adrenal masses with dynamic incremented CT.

Contrast-enhanced dynamic incremented CT scans in 37 patients with 44 small adrenal masses (28 benign and 16 malignant) were reviewed by two observers unaware of the histologic diagnosis to determine if applying morphologic criteria could help differentiate small benign adrenal masses from malignant adrenal masses. Only lesions smaller than 5 cm with diagnoses confirmed by histology (12 masses) or follow-up (32 masses) were included. Features evaluated to suggest a benign diagnosis were homogeneous low attenuation, possibly with punctate contrast enhancement; an enlarged gland (adrenal configuration maintained); a thin or absent rim; round or oval shape with sharp margins; and diffusely homogeneous attenuation about equal to or greater than that of muscle. Features studied to suggest a malignant diagnosis were a thick enhancing rim, invasion of adjacent structures, irregular or poorly defined margins, and inhomogeneous attenuation. Both observers' diagnoses of benign vs malignant lesions with CT criteria were highly statistically significant. The positive predictive value of a benign diagnosis was 100% for both observers and of a malignant diagnosis was 82% and 62% for the two observers. Evaluated singly, all but three diagnostic criteria were statistically significant in differentiating lesions for both observers; the other three criteria were present in a smaller percentage of patients, but nevertheless had positive predictive values for benignancy of 89-100%. We conclude that experienced observers who use CT criteria can often discriminate accurately between benign and malignant small adrenal masses and, in particular, minimize the number of false-negative diagnoses of adrenal metastases. If these results are confirmed and refined by prospective studies, aggressive diagnostic evaluation can be eliminated in some patients with benign adrenal lesions.

Hepatic perivascular lymphedema: CT appearance.

The CT appearance of dilated hepatic lymphatics in liver transplant recipients has been described recently. We have observed similar findings of presumed hepatic lymphatic dilatation and perivascular lymphedema in 20 patients seen over an 8-month period, none of whom had received a liver transplant. Review of these patients' records showed that 18 (90%) of 20 had underlying disease processes that could have caused dilated lymphatics as a result of either increased lymph flow or lymphatic obstruction. We have grouped these processes into three etiologic categories: (1) posttraumatic hepatic lymphatic obstruction, (2) obstruction caused by malignant lymphadenopathy, and (3) congestive hepatomegaly caused by cardiac decompensation. The appearance of hepatic lymphatic dilatation and surrounding lymphedema needs to be recognized so that lymphatic dilatation is not mistaken for dilated intrahepatic bile ducts.

Magnetic resonance imaging of the internal anatomy of the prostate gland.

Previous reports on the value of magnetic resonance imaging of the prostate have been conflicting and frequently pessimistic, in part because of inability to visualize internal prostatic anatomy. Multiple spin-echo sequences were used to determine a sequence that clearly delineated the internal prostatic anatomy in normal volunteers. A thin section, T2-weighted, spin-echo technique displayed the internal prostatic anatomy in great detail, including the central and peripheral zones, the prostatic urethra, and the periprostatic venous plexus. Accurate depiction of the zonal anatomy of the prostate is important in characterizing focal prostatic disease because the vast majority of carcinomas begin within the peripheral zone, whereas benign hypertrophy originates centrally.

Duplex Doppler examination of the liver and portal venous system.

Duplex Doppler scanning has many applications in the evaluation of the liver and the portal venous system. It can be a useful adjunct to real-time sonographic identification of normal and variant anatomy, and lesion detection in the liver and porta hepatis. It is able to document both portal venous thrombosis and portal venous hypertension. It plays an important role in the pre- and postoperative assessment of patients undergoing portosystemic shunts or liver transplants. It allows the observation and measurement of portal venous systemic physiologic responses. In addition to the above applications, duplex Doppler scanning's future potential, including full-field color Doppler imaging, is discussed.

Aortocaval fistula: CT appearance with angiographic correlation.

As CT is often the initial imaging method in the evaluation of suspected complications of abdominal aortic aneurysm, especially rupture of the aneurysm, it is important to be aware of other less common complications that can be detected by CT. A patient with an aortocaval fistula and renal venous hypertension is discussed. The constellation of CT findings that suggest this diagnosis is described as is the angiographic correlation. Awareness of these CT findings, including early equivalent enhancement of the inferior vena cava and aorta; enlarged, poorly functioning kidney; and perirenal "cobwebs," will lead to the appropriate confirmatory angiographic studies.