Microcystic features at US: a nonspecific sign for microcystic adenomas of the pancreas.

Microcystic adenoma of the pancreas is a benign tumor with no malignant potential and may not require surgery if it is asymptomatic. In the past, a mass containing more than six small (<2-cm) cysts at ultrasonography (US) has been considered to be diagnostic for microcystic adenoma. However, a retrospective study of 36 patients with focal or diffuse pancreatic lesions containing over six small cysts demonstrated that this finding can occur in a wide variety of neoplastic and inflammatory lesions, most of which are malignant. These lesions included adenocarcinoma (n = 18), mucinous cystadenocarcinoma (n = 2), islet cell carcinoma (n = 1), lymphoma (n = 1), sarcoma (n = 1), metastases (n = 2), pancreatitis (n = 4), and adenoma (n = 7). Thus, a finding of multiple small cysts in a pancreatic mass is not specific for microcystic adenoma, and if diagnosis is based on US findings alone, many malignant tumors will be misdiagnosed as microcystic adenomas. Furthermore, computed tomography provides only limited assistance in this setting due to overlapping findings. Needle biopsy can be highly accurate in diagnosing both microcystic adenoma and other malignant lesions and should generally be performed for all lesions with the US features described earlier.

Tissue harmonic imaging sonography: evaluation of image quality compared with conventional sonography.

OBJECTIVE: The purpose of this study was to determine if tissue harmonic imaging (THI) sonography produced higher quality images than did conventional sonography. SUBJECTS AND METHODS: A prospective study was performed on 89 patients to compare the image quality of THI sonography with that of conventional sonography. Each examination was performed using THI sonography (transmitted frequency, 2.0 MHz; received frequency, 4.0 MHz) and conventional sonography at 2.5 and 4.0 MHz. The pancreatic area was studied in 60 patients, and other anatomic areas were studied in 68 patients. The images were then graded for penetration, detail, and total image quality. Graders were unaware of the sonographic technique. RESULTS: Of the 60 pancreatic examinations, THI sonography was the best technique for penetration in 45, detail in 54, and total image quality in 50. For the pancreas, THI sonography was significantly better than 2.5-MHz conventional sonography for penetration (p = .0002), detail (p < .0001), and total image quality (p < .0001). THI sonography was significantly better than 4.0-MHz conventional sonography for penetration (p < .0001), detail (p < .0001), and total image quality (p < .0001). Of the 68 examinations of other anatomic areas, THI sonography was the best technique for penetration in 42, detail in 57, and total image quality in 58. For other anatomic areas, THI sonography was significantly better than 2.5-MHz conventional sonography for penetration (p = .05), detail (p < .0001), and total image quality (p < .0001). THI sonography was significantly better than 4.0-MHz conventional sonography for penetration (p < .0001), detail (p < .0001), and total image quality (p < .0001). CONCLUSION: The THI technique improved sonographic image quality.

Color Doppler applications in hepatic imaging.

Color Doppler sonography is an important modality in the non-invasive evaluation of the liver. It is commonly used to evaluate vascular changes which accompany cirrhosis. Doppler techniques are also used to evaluate patients who have undergone liver transplantation or transjugular intrahepatic portosystemic shunt (TIPS) placement. This review describes the various applications of color Doppler in hepatic imaging.

Liver transplant rejection: value of hepatic vein Doppler waveform analysis.

BACKGROUND: To determine whether abnormal hepatic vein Doppler tracings can be used to predict liver transplantation rejection. METHODS: A total of 158 hepatic vein Doppler tracings were obtained on 93 postliver transplant patients (63 patients without rejection and 30 patients with biopsy-proven rejection). Hepatic vein Doppler tracings were scored according to an established grading system (0 = normal triphasic waveform, 1 = dampened waveform, with loss of flow reversal, 2 = completely flat waveform). The hepatic vein Doppler tracings were then correlated with biopsy findings. RESULTS: In the group of 63 patients without rejection, 124 Doppler examinations were performed and graded as follows: 0 = 87 (70%), 1 = 31 (25%), and 2 = 6 (5%). In the group of 30 patients with biopsy-proven rejection, 34 Doppler examinations were performed and graded as follows: 0 = 16 (47%), 1 = 14 (41%), and 2 = 4 (12%). The sensitivity of abnormal hepatic vein Doppler tracings for detection of rejection was 53% and the specificity was 70%. The positive predictive value of an abnormal hepatic vein Doppler tracing was 33% and the negative predictive value of a normal Doppler tracing was 84%. CONCLUSIONS: Abnormal hepatic vein Doppler tracings are observed in patients with and without liver transplant rejection. Abnormal tracings cannot be used to predict liver transplant rejection.

Pneumothorax and pneumomediastinum after laparoscopic surgery.

Pneumothorax, pneumomediastinum, pneumopericardium, and subcutaneous emphysema have been described as complications of laparoscopy. This study evaluates the incidence and significance of these extra alveolar collections of air. We found that pneumomediastinum with or without pneumothorax was not associated with significant morbidity and is more likely after laparoscopic fundoplication than other laparoscopic surgeries. The presence of pneumomediastinum after fundoplication is a normal finding. However, pneumothorax has clinical significance and should be considered pathological.

Obstetric embolotherapy: effect on menses and pregnancy.

PURPOSE: To determine the long-term effects of uterine embolotherapy with gelatin sponge pledgets on menses and fertility. MATERIALS AND METHODS: Between June 1990 and December 1995, 17 women (aged 20-44 years) with obstetric hemorrhage underwent selective gelatin sponge pledget embolization of uterine vessels. Gynecologic information in the 12 women who did not undergo hysterectomy was obtained by means of direct communication or from the patients' physicians. RESULTS: In 11 (92%) of the 12 women, normal menses resumed within 2-5 months of the procedure. There were no complications related to embolotherapy. The follow-up period was 1-6 years. All three patients who desired to conceive had full-term, healthy newborns. The only patient who is amenorrheic is currently receiving medroxyprogesterone acetate; her ultimate menstrual and fertility status cannot yet be determined. CONCLUSION: Selective embolization of the uterine vessels with gelatin sponge pledgets is a safe and effective method of managing pregnancy-related hemorrhage. Our results suggest that women who undergo this procedure can expect to have a return of normal menses with no adverse effect on fertility.

MRI of the liver. A pictorial essay.

Magnetic resonance imaging (MRI) is an extremely useful modality for evaluation of the complex pathophysiology of the liver. The high degree of soft tissue contrast afforded by MRI accurately detects and characterizes both focal and diffuse abnormalities of the liver. In this article we present a pictorial review of MRI of the liver.

Atypical angiographic appearance of a superficial femoral artery mycotic aneurysm.

An unusual presentation of mycotic aneurysm is described. In this case, a large thrombosed mycotic aneurysm of the superficial femoral artery was associated with segmental occlusion of the adjacent artery. Small vessels were delineated in the periphery of the aneurysm on angiography.

Paraumbilical venous collateral circulations: color Doppler ultrasound features.

Using Color Doppler ultrasonography to trace the dilated paraumbilical vein to its connection with systemic veins in 27 patients, we have found four major pathways: In type 1 (63%), the vein connected with the external iliac vein via the inferior epigastric vein. In type 2 (3.7%), the vein connected with the saphenous vein via the superficial epigastric vein. In type 3 (22.2%), the vein connected with the internal thoracic vein via the superior epigastric vein. Type 4 (11.1%) is a combination of types 1 and 2. A frank caput medusa was not seen, but occult caput medusa were seen in two patients. Turbulent flow was seen at the junction between inferior epigastric and external iliac veins, paraumbilical and superficial epigastric veins, and superficial epigastric and saphenous veins in some patients. Color Doppler ultrasonography is a convenient, noninvasive method for determining the course and associated hemodynamic changes in the paraumbilical collateral circulation.

Systemic venous enhancement patterns during dynamic abdominal CT.

In 25 patients we assessed the enhancement of abdominal venous structures during dynamic computed tomography (CT). The degree of venous enhancement demonstrated great variation. In six instances (out of 250 observations) a vessel was visually perceived as not enhancing and potentially thrombosed, including three gonadal veins. CT measurements were helpful in identifying enhancement, but were occasionally low enough that thrombosis remained a radiological consideration. The great variation in venous enhancement makes the diagnosis of thrombosis suspect, based on CT alone. Corroboration of this finding is suggested, when clinically relevant.

Transjugular intrahepatic portosystemic shunt: correlation of portal vein velocity measurements and portosystemic pressure gradients.

To assess the relationship between portal vein velocity measurements and portosystemic gradients, color Doppler sonography was performed on 12 patients before and after transjugular intrahepatic portosystemic shunt placement. An additional patient was examined before and after shunt modification. The average maximum portal vein velocity increased from 15.7 cm s-1 before shunt placement to 43.5 cm s-1 after shunt placement, while the average portosystemic gradient decreased from 22.0 mm Hg before shunt placement to 7.9 mm Hg after shunt placement. Flow was observed within the shunt in 11 of the 12 cases. Shunt velocity was measurable in nine patients, with an average value of 115.7 cm s-1. Reversal of intrahepatic portal vein flow was observed in 10 cases following shunt placement. Color Doppler sonography is a useful non-invasive tool in the evaluation of intrahepatic portosystemic shunts, and changes in portal vein velocity correlate well with changes in the portosystemic gradient.

Abscess formation as a late complication of dropped gallstones.

We describe a case of abscess formation 1.5 years postoperatively in a patient with dropped gallstones from laparoscopic cholecystectomy. The entity was initially recognized on computed tomography (CT) and the diagnosis was confirmed with ultrasound. Although this is a rare complication of laparoscopic cholecystectomy, it should be recognized as a potential source of abscess formation even in a patient presenting months after the procedure.

Renal lymphoma in Castleman's disease.

An unusual case of renal lymphoma occurring in a patient with Castleman's disease is presented. The radiographic features and the relationship to the lymphoproliferative disorders, Castleman's disease, and multicentric angiofollicular lymph node hyperplasia are described.

Variability of hepatic vein Doppler tracings in normal subjects.

A prospective study was undertaken to determine the variability of hepatic vein Doppler waveforms in normal subjects. Seventy-five patients without liver or heart disease underwent Doppler examination of the middle hepatic vein. Normal triphasic tracings were observed in 68 subjects, while flattened tracings were observed in seven subjects. In addition, in four of the seven subjects with flattened tracings, an increase in pulsatility was seen during prolonged inspiration. We conclude that there is variability of hepatic vein tracings in normal subjects and that respiratory maneuvers can alter these tracings.

Hepatic mass in Budd-Chiari syndrome: CT and MRI findings.

We describe a case of Budd-Chiari syndrome, secondary to a hypercoagulable state, which produced a mass lesion on computerized tomography (CT) and magnetic resonance imaging (MRI) examinations. The mass simulated a tumor, but proved to be an area of hemorrhagic necrosis upon biopsy. The finding of a space occupying lesion may not always indicate a tumor in a patient with the Budd-Chiari syndrome. The causes, pathologic changes, and radiologic findings of Budd-Chiari syndrome are discussed.

Color Doppler sonography of vascular malformations of the liver.

Nine cases of intrahepatic vascular malformations diagnosed using color Doppler sonography are described. These consisted of six cases of intrahepatic portal-hepatic venous shunts and three cases of arteriovenous fistulas. Among these is a case of multiple intrahepatic portal-systemic shunts. The sonographic findings and theories explaining the formation of vascular malformations in the liver are discussed.