Long-term follow-up after TIPS: use of Doppler velocity criteria for detecting elevation of the portosystemic gradient.

PURPOSE: To evaluate the performance of Doppler ultrasound as a screening test for detecting elevated portosystemic gradients in failing transjugular intrahepatic portosystemic shunts (TIPS). MATERIALS AND METHODS: Twenty-seven of 61 patients who underwent TIPS creation between November 1991 and March 1996 were studied. At routine intervals, angle-corrected velocity measurements of portal venous and intrashunt blood flow (at the portal venous, middle, and hepatic venous levels of the shunt) were obtained. These were compared with portal hemodynamics for diagnostic accuracy in predicting clinically significant elevation of the portosystemic gradient. Venographic and manometric correlations were obtained on all patients available for follow-up and were not limited to those with symptoms or "abnormal" Doppler studies. Receiver-operating characteristic (ROC) curves were done. Linear regression was done to study correlation of shunt velocities with portal pressure, and logistic regression was done to predict shunt stenosis with use of shunt velocities. RESULTS: The most accurate location for shunt velocity measurement was the main portal vein, but this had an area under the ROC curve of only 0.70. Accuracy of any velocity threshold (including maximum shunt velocity) was no greater than 70%. Maximum shunt velocity of less than 60 cm/sec was 93% specific for detecting shunt restenosis, but only 25% sensitive, for an overall accuracy of 64%. High sensitivity (90%) could only be achieved with poor specificity (< 33%). Linear regression revealed poor correlation between shunt or portal vein velocity measurements and portal pressure (/r/ < 0.23 for all). CONCLUSIONS: Intrashunt and portal venous Doppler velocities alone do not accurately predict elevation of the portosystemic gradient on long-term follow-up after TIPS.

Contemporary diagnostic approaches for nonpalpable carcinoma of the breast: the role of the radiologist.

Over the past 25 years the radiologist's role in the diagnosis of breast cancer has expanded from merely confirming the clinical suspicion of neoplasm to detecting occult nonpalpable tumors and now percutaneously obtaining tissue for histologic assessment. The cancer the radiologists discover is smaller in size and earlier in stage, allowing more conservative surgical approaches. This, coupled with adjuvant radiation therapy and chemotherapy, is producing newly demonstrated mortality reduction in this disease so feared by American women.

Color Doppler sonography: anatomic and physiologic assessment of the thyroid.

The purpose of this study was to assess the potential application of color Doppler sonography in thyroid imaging. Thyroid nodules and other thyroid pathology detected by color Doppler ultrasound and nuclear scintigraphy were compared in 115 patients. The majority of "cold" nodules demonstrated a peripheral rim of color flow and no internal color flow with color Doppler sonography. A large number of "hot" nodules demonstrated internal color flow. Color Doppler sonography was helpful in delineating nodules in otherwise inhomogeneous glands. We determined that color Doppler cannot reliably distinguish benign from malignant thyroid nodules; fine-needle aspiration biopsy remains the most accurate method in differentiating benign and malignant lesions. We suggest that color Doppler sonography plays only a limited role in the evaluation of nodular thyroid disease at this time. The color Doppler appearance of other thyroid disorders (including toxic multinodular goiter, Graves' disease, and thyroiditis) is discussed.

Benign circumscribed breast masses. Mammographic and sonographic appearance.

Mammography is an excellent screening tool for the detection of breast masses. One of the goals of the radiologist is to separate benign breast masses warranting no intervention from the indeterminate and malignant masses that require histologic evaluation. Thorough mammographic and sonographic work-up of lesions detected at screening will reduce the number of biopsies performed and increase the true positive biopsy rate. By systematically evaluating a breast mass as to its density location, size, margins, and interval change, one can separate benign lesions from those requiring additional work-up and those that will require a biopsy diagnosis. Any features suggesting malignancy should prompt histologic assessment. For many women, FNAB or large-core needle biopsy, guided either stereotactically or sonographically, will not only reduce the morbidity associated with excisional biopsy but also decrease the cost of evaluating questionable lesions found at screening. Ultrasound examination will further reduce the number of biopsies by separating cysts from solid and indeterminate lesions that require further evaluation. What rate of carcinoma in biopsy specimens should be the mammographer's guideline? Ciatto et al found in his series a 30% positive predictive value for mammography in detecting carcinoma. In the author's opinion, a goal to strive for should be in the range of 40%. The mammographer's experience and confidence as well as patient's compliance with follow-up recommendations will help the mammographer reach this goal.

Is bilateral lower extremity compression sonography useful and cost-effective in the evaluation of suspected pulmonary embolism?

OBJECTIVE: Because deep venous thrombosis is clinically linked with pulmonary embolism and often treated similarly, we sought to assess the usefulness of obtaining bilateral lower extremity compression sonograms when findings on ventilation-perfusion lung scans indicate a low or indeterminate probability of pulmonary embolism. Demonstration of deep venous thrombosis would provide a rationale for treating both pulmonary embolism and deep venous thrombosis. MATERIALS AND METHODS: Two hundred twenty-three consecutive patients with suspected pulmonary embolism had ventilation-perfusion lung scans and concurrent bilateral lower extremity compression sonograms; 34 also had pulmonary arteriography. RESULTS: In 75 cases, the results of ventilation-perfusion lung scanning indicated an indeterminate probability of pulmonary embolism. Evidence of thrombosis was seen on sonograms in 11 of these 75. In the remaining 64, 17 underwent pulmonary arteriography and four (24%) had pulmonary embolism. Findings on lung scans indicated a low probability of pulmonary embolism in 70 of 223 patients. Evidence of thrombosis was seen on sonograms in 11 of these 70. Five of the remaining 59 underwent pulmonary arteriography and one (20%) had pulmonary embolism. According to the 1993 Medicare Fee Schedule, if all 145 patients whose lung scans were nondiagnostic had sonography and only those with normal sonograms had pulmonary arteriography, the professional and hospital charges would be $359,552. If all 145 had pulmonary arteriography without sonography, the charges would be $395,031. CONCLUSION: If ventilation-perfusion lung scans indicate a low or an indeterminate probability of pulmonary embolism and bilateral lower extremity compression sonography is performed, only those patients with normal sonographic findings would need further study. Thus, 15% (22/145) of patients could be spared pulmonary arteriography, and the estimated savings in cost would be 9%.

Computerized tomography in persons with Down syndrome and atlantoaxial instability.

Atlantoaxial instability has been reported to occur in 9-31% of persons with Down syndrome. The authors studied a subsample of patients with this chromosomal disorder who had both routine roentgenograms and computerized tomographic examinations. Computerized tomography revealed numerous skeletal anomalies of the C1-C2 region as well as spinal cord compression that were not visualized on plain roentgenograms. In addition, an apparent discrepancy of the atlanto-dens interval measurements between the two procedures was noted. The measurements of the plain roentgenograms were significantly greater than those obtained by computerized tomography, which is due to the magnification factor in plain roentgenograms.

A longitudinal study of atlanto-dens relationships in asymptomatic individuals with Down syndrome.

This study was designed to investigate the natural history of atlantoaxial instability in individuals with Down syndrome and to determine whether significant changes in C1-C2 relationship are taking place over time. Although more than 400 patients with Down syndrome who are presently followed at the Child Development Center had cervical spine radiographic examinations in the past, only 141 patients who had serial radiological examinations and whose radiographs were available for reevaluation participated in this study. The results of our investigations revealed that there were only minor changes (1 to 1.5 mm) of atlanto-dens interval measurements over time in 130 (92%) patients with Down syndrome. Eleven patients (8%) had changes of atlanto-dens interval measurements between 2 and 4 mm over time; however, none of these patients had any clinical symptoms. The analyses of data obtained from several subgroups (males and females, various age groups, and patients with and without atlantoaxial instability) did not show any significant changes of atlanto-dens interval measurements of successively obtained radiographs. Our recommendations for and rationale of routine screening for atlantoaxial instability and follow-up examinations are discussed in detail.

Diazald, a newly recognized antimicrobial agent and its spectrophotometric determination.

Diazald, a chemical intermediate for the synthesis of biologically active compounds, was found to be a potent in vitro antimicrobial agent against yeasts, yeast-like and filamentous fungi as well as Gram-positive and Gram-negative bacterial strains. Its activity is not inhibited by either para-aminobenzoic acid (PABA) or the nitroso group-specific 2-aminothiazole-methoxyimino acetic acid (ATMAA). This suggests that the molecule as such is responsible for the antimicrobial activity. For its quick measurement a sensitive spectrophotometric method has been developed.

Skeletal anomalies of the upper cervical spine in children with Down syndrome.

This study showed that a significantly greater number of children with Down syndrome (45 to 78) have cervical spine anomalies than an age- and sex-matched group of normal children (3 of 38). Moreover, children with Down syndrome who had atlantoaxial instability had an increased frequency of cervical spine anomalies (31 of 39) as compared with an age- and sex-matched group of children with this chromosome disorder who did not have atlantoaxial instability (14 of 39).

Radiation exposure to patients receiving routine scoliosis radiography measured at depth in an anthropomorphic phantom.

Concern about the amount of radiation received during scoliosis evaluation and treatment led us to measure radiation exposure in an anthropomorphic phantom to determine the increased risk of breast cancer in young women with scoliosis. Assuming that 22 radiographic examinations were performed over the course of scoliosis treatment, the increased relative risk of breast cancer was determined to be 0.22% in these patients.

Iatrogenic changes at the venotomy site after percutaneous placement of the Greenfield filter.

To determine the prevalence of iatrogenic abnormalities associated with percutaneous delivery of Greenfield filters, the authors prospectively evaluated 69 peripheral veins used for filter placement in 68 patients. Of the 69 venotomy sites, 63 were not associated with preexisting thrombosis and were evaluated with compression and Doppler ultrasound within 1 week of placement and over 13-541 days. New thrombosis developed at the puncture site in nine of 63 sites (14.3%), although clinical suspicion of clot was raised in only one patient. Fifty-four sites (85.7%) showed no evidence of acute deep venous thrombosis, even though three patients had signs and symptoms suggestive of thrombosis. During the follow-up, most new thromboses resolved, yielding a 96.3% long-term patency rate. The authors conclude that postplacement increase in symptoms of venous stasis and occlusion may not correlate with placement site thrombosis. New filters should be evaluated for their ability to capture potential pulmonary emboli while maintaining caval patency and for mechanical and biologic stability because placement site complications occur at low rates and resolve in most cases.

Grade I hydronephrosis: pulsed Doppler US evaluation.

This study was undertaken to determine whether the presence of blood vessels could mimic the appearance of grade I hydronephrosis on sonograms and thus cause false-positive readings. One hundred consecutive patients with grade I hydronephrosis were examined. Sample volumes were obtained with pulsed Doppler ultrasonography (US) at the site of the greatest separation of the central renal sinus echoes to determine if the separation was fluid accumulating in the collecting system, as in obstruction, or if the separation was actually caused by vessels that mimic hydronephrosis. Vascular structures accounted for the separation of the sinus echoes in 43% of patients. In patients 12 years of age or younger, this frequency rose to 61%. The simple procedure of evaluating the renal sinus echo separation with pulsed Doppler US should decrease the frequency of false-positive diagnoses of hydronephrosis and thus diminish the need for further confirmatory testing.

Ultrasound evaluation of cholelithiasis in the morbidly obese.

The ability to detect gallstones in the morbidly obese population has been questioned in recent literature. Utilizing state-of-the-art, real-time ultrasound equipment, 44 morbidly obese patients were examined prior to gastric exclusion surgery and concomitant cholecystectomy. The 91% sensitivity and 100% specificity of gallstone detection in this series matches the results for the general population. This study provided the unique opportunity to evaluate a large number (34) of negative ultrasound examinations, with subsequent surgical confirmation yielding a negative predictive value of 97%. This confirms the continued role of ultrasound in the evaluation of cholelithiasis.

Atlantoaxial instability in individuals with Down syndrome: epidemiologic, radiographic, and clinical studies.

Atlantoaxial instability is a relatively frequent finding in individuals with Down syndrome. We examined 404 patients with this chromosome disorder and observed their atlanto-dens intervals and spinal canal widths to be significantly different from children without Down syndrome. Significant differences were also noted between boys and girls with Down syndrome in spinal canal widths but not in atlanto-dens interval measurements. When different neck positions were compared, measurements obtained in flexion were significantly greater than in extension or in neutral position. In addition, more patients had greater than or equal to 5 mm atlanto-dens interval measurements in flexion than in extension or neutral. A total of 59 (14.6%) of 404 patients displayed atlantoaxial instability. Fifty-three (13.1%) patients had asymptomatic atlantoaxial instability, and special precautions will have to be taken with this group of children. Six (1.5%) patients had symptomatic atlantoaxial instability who underwent surgery to prevent further injury to the spinal cord. In our follow-up studies of 95 patients with Down syndrome, we did not find any significant changes during either clinical or radiographic reexaminations.

Atlantoaxial instability in Down syndrome: roentgenographic, neurologic, and somatosensory evoked potential studies.

To identify patients with Down syndrome and asymptomatic atlantoaxial instability who are at increased risk for developing neurologic symptoms, we studied 27 patients with this skeletal disorder and compared them with an age- and sex-matched group of 27 patients with Down syndrome without atlantoaxial instability. A third group of six patients had symptomatic atlantoaxial instability. The mean atlanto-dens intervals and the mean spinal canal widths among the three groups were significantly different. There were no significant differences in mean composite neurologic scores and somatosensory evoked responses between patients in the asymptomatic group and those in the control group. However, when a subsample of patients with high and low latencies (greater than 1 SD below and above the mean) was formed and comparisons were made with roentgenographic findings, there was a high correspondence between somatosensory evoked potential latencies and atlanto-dens interval measurements. We conclude that no single assessment technique, but a combined approach using roentgenographic, CT scan, neurologic, and neurophysiologic investigations, will provide information of the risk status of patients with Down syndrome and atlantoaxial instability.

Deep venous thrombosis: US assessment using vein compression.

To assess vein compressibility as a simple ultrasound (US) technique to determine the presence of venous thrombi, 51 patients undergoing contrast material venography of the lower extremity because of a clinical suspicion of deep venous thrombosis (DVT) also underwent high-resolution US evaluation of the veins. DVT was diagnosed on 28 venograms. In 25 patients US studies demonstrated non-compressibility of the veins, indicating the presence of clot. In 23 patients with normal venograms, US examinations demonstrated total compressibility of the veins, indicating the absence of DVT. Clots below the knee were not depicted by US. In this study US had a sensitivity of 89% and a specificity of 100%.