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The mainstay of therapy for acute cholecystitis is cholecystectomy, which has a mortality of 5-30% in high-risk patients such as the elderly or critically ill. An alternative treatment option in patients suffering from acute cholecystitis with contraindications to emergency surgery is percutaneous cholecystostomy (PC) followed by interval laparoscopic cholecystectomy. Percutaneous cholecystostomy yields 10-12% mortality in high-risk patients and is therefore a safe temporizing measure, allowing delayed, elective cholecystectomy when the patient is in better condition for surgery.Hospital charts and radiology films were reviewed for all 50 patients who underwent PC for acute cholecystitis between January 1990 and September 1993. Most patients were high risk for emergency cholecystectomy by virtue of their critical illness or underlying medical condition. Twenty-five patients went on to have interval cholecystectomies. We recorded whether they underwent laparoscopic or open cholecystectomy, as elective or emergency procedures, and we recorded direct complications, mortality, and postoperative length of hospital stay.Relief of symptoms occurred within 48 h of PC in 90% of patients, and two patients had complications of PC. Laparoscopic cholecystectomy was attempted in 13 patients and competed in nine. Four patients (31%) required conversion from laparoscopic to open cholecystectomies due to extensive adhesions (3) or bleeding (1). Three patients had direct complications of laparoscopic cholecystectomy. There was no mortality or major bile duct injury.Percutaneous cholecystostomy followed by interval laparoscopic cholecystectomy is a safe, minimally invasive approach which can be employed safely in the critically ill patient when contraindications to emergency surgery exist.

The authors studied the prevalence of abnormalities at abdominal ultrasonography (US) in patients with acquired immunodeficiency syndrome (AIDS), the temporal change in prevalence, and the use of US to correlate clinical indications with these abnormalities.From 1983 to 1991, 899 AIDS patients were seen, representing 89.36% of the 1,006 AIDS patients in the province during that time. Of these, 414 underwent 684 US studies, 399 of which were able to be reviewed.US results showed abnormalities in 264 of the 399 studies, including splenomegaly (n = 124), lymphadenopathy (n = 83]), gallbladder and bile duct abnormalities (n = 80), hepatomegaly (n = 77), and ascites (n = 54). Clinical indications with the highest frequency of abnormal findings included hepatosplenomegaly (n = 337) and abnormal liver function tests (n = 270). Lymph nodes more than 3 cm in diameter (in 10 of 83 patients with enlarged nodes) always represented an abnormality other than reactive hyperplasia. The percentage of abnormal results went from 25% in 1984 (two of nine studies) to 81% in 1990 (77 of 95 studies).The prevalence of abdominal abnormalities depicted at US in AIDS patients has increased since 1983.

To determine how long Gianturco-Rosch metal stents remain patent when used as the initial treatment for malignant obstruction of the common bile duct.The patency of Gianturco-Rosch metal stents was prospectively studied in 26 patients with malignant obstructive jaundice. Biliary obstruction was caused by pancreatic carcinoma (n = 15), cholangiocarcinoma (n = 10), or metastatic lymphadenopathy (n = 1). Follow-up information was obtained every 3-4 months until death.Stent insertion was successful in all patients. Stent occlusion occurred in nine patients (35%). The overall mean patency period was 39.9 weeks. Adequate biliary drainage for a minimum of 80 weeks or until death was achieved in 19 patients (73%). Life-table analysis predicted stent patency rates of 86%, 75%, and 69% at 12, 24, and 48 weeks, respectively.These results are better than those previously reported in patients with plastic endoprostheses. The authors believe that insertion of the metal stent is the procedure of choice in patients with inoperable malignant biliary obstruction.

PURPOSE: To evaluate the authors' experience with treatment of symptomatic hepatic cysts by means of percutaneous catheterization and sclerosis. MATERIALS AND METHODS: Twenty patients with 24 symptomatic hepatic cysts underwent percutaneous drainage and sclerosis. Ten patients had polycystic disease, and 10 had solitary cysts. Sclerosants used were alcohol, tetracycline, doxycycline, or a combination. RESULTS: Twenty-one of 24 cysts in 17 of 20 patients were treated successfully. Treatment was unsuccessful in three patients: one patient with innumerable medium-size and small cysts, one patient in whom only a needle was inserted (no catheter), and one patient with a cystic metastasis (rather than a simple cyst) that recurred. Complications included pleural effusion in two patients and secondary infection in one patient. The range of blood alcohol levels was 0-0.8 mg%. CONCLUSION: Percutaneous catheter drainage with sclerosis is an effective method of therapy for symptomatic hepatic cysts; careful patient s...

The purpose of this paper is to review the indications for transrectal ultrasound; to briefly describe the sonographic technique; to describe the sonographic findings of prostatic carcinoma; to review the indications for transrectal sonographic-guided biopsy; and to discuss the controversles of routine screening and staging.

The purpose of this study was to review the embryology, classification, imaging features and treatment options of Mullerian duct anomalies. The three embryological phases will be described and the appearance of the seven classes of Mullerian duct anomalies will be illustrated using hysterosalpingography, ultrasound and MRI. This exhibit will also review the treatment options, including interventional therapy. The role of imaging is to help detect, classify and guide surgical management. At this time, MRI is the modality of choice because of its high accuracy in detecting and accurately characterising Mullerian duct anomalies. In conclusion, radiologists should be familiar with the imaging features of the seven classes of Mullerian duct anomalies, as the appropriate course of treatment relies upon the correct diagnosis and categorisation of each anomaly.

To determine which of several variables--age, serum level of prostate-specific antigen (PSA), findings of transrectal ultrasonography (TRUS) and findings of digital rectal examination (DRE)--are the best predictors of positive prostate biopsy results.An urban, university-affiliated tertiary care hospital.a cohort of 1330 consecutive men referred to the diagnostic imaging department for TRUS and TRUS-guided prostate biopsy. Each patient was referred after examination by a urologist because of clinical suspicion of prostate cancer.All of the men had undergone prior determination of serum level of PSA. Repeat DRE was performed at the time of imaging. The variables age, PSA level, TRUS findings and DRE findings were tested aline and in combination as predictors of positive biopsy results by means of logistic regression analysis. A summary of percentage risk for positive biopsy results was constructed for each combination of statistically significant variables, stratified for age.Cancer was detected in 541 men (40.7%). A strong correlation was observed between serum PSA level and the likelihood of positive biopsy result (p0.001). Of 402 men with normal age-specific PSA, 109 (27.1%) had positive biopsy results. Of 403 men with PSA of 10 ng/mL or more, 233 (57.8%) had cancer. The level of serum PSA was also related to the number of prostate sextants harbouring cancer (p0.001). TRUS findings at the time of biopsy were a strong predictor of cancer of the PSA level was abnormal (p0.001). DRE results alone did not correlate with positive biopsy results, regardless of age, PSA level of TRUS findings.Men in whom there is a clinical concern for prostate cancer should undergo prostate biopsy if there is any elevation of age-specific PSA, particularly if the findings of TRUS are also abnormal. Because DRE alone was not predictive of biopsy outcome, algorithms for prostate cancer detection that rely on abnormal DRE results to identify men who should undergo biopsy will miss a significant number of cancers.

Small catheters containing 20 MHz transducers have recently become available for high resolution endoluminal ultrasound. We report our early use of this technique to image and stage esophageal carcinoma. Fifteen patients undergoing high resolution endoluminal ultrasonography for suspected esophageal carcinoma were studied. Twelve of these patients also underwent computed tomography and pathologic correlation was available in seven. Satisfactory esophageal examination was possible in 14 of 15 patients. Of those with pathologic correlation, the depth of tumor invasion was correctly staged by high resolution endoluminal ultrasonography in six of seven patients and by computed tomography in only three of seven patients. Lymph node assessment correlated poorly with pathologic findings for both high resolution endoluminal ultrasound and computed tomography. With the increasing use of preoperative radiation therapy, we believe these early results predict a potential role for high resolution endoluminal ultrasonography in the staging of esophageal carcinoma.

The dimensions of the infrarenal inferior vena cava during quiet respiration, single leg lifting, and breath-holding were assessed using sonography in 156 patients. Sonographic assessment of infrarenal inferior vena caval dimensions was feasible in 69% of patients. Measurements during breath-holding were significantly greater than during quiet respiration (P < 0.001) and leg lifting (P < 0.005), although in approximately one quarter of the patients the mean calculated diameter was greatest during quiet respiration. we conclude that sonographic assessment of infrarenal inferior vena caval dimensions is feasible, but it should be performed during quiet respiration and breath-holding to allow for variation with different respiratory maneuvers.

To assess the long-term outcome in patients with acute cholecystitis treated initially by percutaneous cholecystostomy, the authors reviewed the medical and radiology records of all such patients treated at their hospital from January 1990 to September 1993. Of the 50 patients, 29 had calculous and 21 had acalculous cholecystitis. In the group with calculous cholecystitis, 1 of the patients required no further treatment, 3 subsequently underwent percutaneous stone removal, 14 underwent elective cholecystectomy, 6 underwent emergency cholecystectomy and 5 died of the underlying condition shortly after cholecystostomy. In the group with acalculous cholecystitis, 12 of the patients needed no further treatment after a mean follow-up period of 12 months; 8 of these underwent follow-up ultrasound examination, which revealed gallbladder calculi in only 1 patient. Four patients underwent elective cholecystectomy, 1 underwent emergency cholecystectomy, and 4 died of the underlying condition shortly after cholecystostomy. Over the long term, 23 (79%) of the 29 patients with calculous cholecystitis underwent surgery or removal of calculi. In the other group surgery was required in only 5 (24%) of the 21 patients. The authors conclude that percutaneous cholecystostomy is a useful temporizing measure, which allows patients with calculous cholecystitis to undergo elective cholecystectomy. In most cases of acalculous cholecystitis the procedure is curative, obviating the need for cholecystectomy.

This study was undertaken to confirm the utility of systematic transrectal ultrasound-guided prostate biopsy in diagnosing cancer in patients with abnormal findings on digital rectal examination or abnormal levels of prostate-specific antigen (or both). The authors also wanted to determine the diagnostic advantage of taking six sextant biopsy samples rather than four quadrant samples. In a prospective study of 669 men examined between July 1992 and April 1993 at a tertiary-care hospital, core samples were obtained from any visualized or palpated abnormalities, the three other "normal" quadrants (apices and bases) and the two parasagittal midzones. The glands of 403 of the patients (60%) had an abnormality detectable by ultrasonography, and 233 of the patients (35%) had adenocarcinoma, proven by histologic examination. Of the 169 cases of adenocarcinoma initially indicated by ultrasonography, the suspected lesion was histologically benign in 66 (39%), but malignancy was found in another portion of the gland. In 18 (8%) of the 233 patients with adenocarcinoma, the only positive result was obtained from the additional core biopsy samples from the midzone. This study confirms that the ultrasonographic characteristics of cancer are variable, that many tumours (130 [56%] in this study) are detected in areas that are normal on ultrasonography and digital rectal examination, and that the detection sensitivity is increased (by 8% in this study) when two midlobe parasagittal plane biopsy samples are added to the four standard quadrant samples.

Hepatic cysts are a common finding in autosomal dominant polycystic kidney disease (ADPKD) [1]. Although polycystic kidney disease often leads to renal failure, polycystic liver disease is usually of little or no clinical consequence. However, large liver cysts may occasionally compress the common hepatic duct, leading to obstructive jaundice [2]. We describe a patient with ADPKD who was initially not considened for renal transplantation because of obstructive jaundice. Two large cysts adjacent to the common hepatic duct were drained percutaneously and sclenosed with ethanol. After cyst ablation, liven function returned to normal, allowing the patient to undergo successful renal transplantation.

Expanding metal stents were used to treat symptomatic pancreatic duct obstruction in two patients with chronic pancreatitis. Both patients initially underwent percutaneous external pancreatic duct drainage and then had metal stents inserted for internal drainage. Both patients remained asymptomatic, and the stents were patent during short-term follow-up periods of 6 and 9 months, respectively. Percutaneous insertion of metal stents, which can be performed to treat pancreatic duct obstruction after a trial of external drainage has been shown to relieve the patient's symptoms, should be considered as an alternative to endoscopic stent placement or surgical drainage.

Eleven cases of bilateral diffuse microlithiasis of the testes were evaluated sonographically. The presence of testicular microlithiasis was coincidental to the presence of testicular neoplasms (n = 2), nontesticular malignant lesion in the abdomen or chest (n = 2), subfertility (n = 2), varicocele (n = 1), epididymitis (n = 1), testicular maldescent (n = 1), scrotal trauma (n = 1), and transient scrotal pain (n = 1). Clinical follow-up suggested that testicular microlithiasis is an asymptomatic nonprogressive condition. Sonographic examination of testicular microlithiasis shows diffuse hyperechoic nonshadowing foci measuring 1-2 mm in diameter throughout both testes. The diagnosis of testicular microlithiasis was pathologically proved in five cases. In six cases, the diagnosis was made on the basis of the sonographic appearance (n = 6), clinical information and follow-up (n = 6), and radiologic demonstration of testicular microcalcifications (n = 3). The sonographic appearance of testicular microlithiasis is specific, and we believe that biopsy or orchiectomy in these cases is unnecessary.

The sonographic criteria for diagnosis of retinal detachment and vitreous membranes are well established, and in most cases a diagnosis can be made. However, in difficult cases, differentiation between the two may be difficult. In this study the use of high-resolution color flow Doppler was evaluated for differentiating between retinal detachments and vitreous membranes. Sonographic evaluation, including color flow Doppler, was performed in 25 symptomatic eyes. Seven eyes had areas of retinal detachment, all of which had detectable blood flow within at least a portion of the detached retina. Fifteen eyes had vitreous hemorrhages or membranes in which no flow was detected. Two diabetic patients with vitreous membranes and no retinal detachment did have flow detectable within the neovascular membranes. Another patient, who had a complete choroid detachment after surgery, demonstrated good flow within the area of detachment. It is concluded that in difficult cases high-resolution color flow Doppler can enable differentiation of an area of retinal detachment from a vitreous membrane in a patient without diabetes.

This report reviews the cases of 12 patients in whom ultrasound examination revealed endometrial cavity echoes that were more prominent than expected. Dilatation and curettage or hysterectomy, or both, in these patients revealed a spectrum of endometrial pathology in 83 per cent of the patients, including carcinoma in 33 per cent and normal findings in 17 per cent.

Six serious pleural complications (three empyemas, two hemothoraces, and one bilious effusion) have occurred after use of the right intercostal approach to the upper abdomen in 230 interventional radiologic procedures performed over the last 3 years. The anatomy of the pleural reflection in the right costophrenic sulcus is reviewed and correlated with a dissection study of the course of right intercostal needle punctures in three cadavers. The pleural reflection reaches the level of the 10th rib in the midaxillary line, and in the cadaver study, all 9th- 10th interspace punctures clearly traversed pleura, diaphragm, and peritoneum to reach the liver. The widely held belief among radiologists that the pleura can be deliberately avoided in transhepatic cholangiography and biliary drainage is shown to be false. It is believed that most needle punctures traverse the costophrenic sulcus, through pleura but below lung, despite the low incidence of reported pleural complications. a left subxiphoid approach avoiding the pleura is recommended in patients with abscesses, ascites, emphysema, anxiety, and, in the case of biliary drainage, benign or purely left-sided disease. When using the intercostal approach, the minimum number of needle passes, careful route planning, antibiotic prophylaxis, and postprocedural chest radiography are strongly recommended.

In a number of cases the ultrasound examination of the left upper quadrant showed an appearance suggesting a fluid collection around the superior and lateral aspects of the spleen. Subsequent investigations including careful real-time evaluation, computed tomography, and magnetic resonance imaging have demonstrated that the pseudo-"fluid collection" is the normal left lobe of the liver extending into the left subdiaphragmatic space to lie superior and even lateral to the spleen. The echogenicity of the normal liver was observed to be less than that of the normal spleen. The ability to simultaneously visualize both the liver and the normal spleen at the same depth and the same field of view gives a true indication of the relative echogenic consistency of the liver and the spleen, which is different from that which had been previously reported.

We have been using a high resolution real time ultrasound mechanical sector scanner to visualize the carotid bifurcation. Twenty-six patients were studied before carotid arteriography for transient ischemic attacks. One bifurcation was not adequately visualized. Of the remaining 51, plaques were identified correctly in 29; absence of plaques was identified correctly in 15; small plaques were demonstrated by ultrasound in two that did not appear on the arteriogram; and four small plaques and one significant stenosis were not identified by ultrasound.

Abdominal sonograms were obtained for three patients who had clinically suspected abscesses. There were abnormal fluid collections that, when viewed from a posterior position, demonstrated a horizontal line representing an air-fluid level. Abdominal abscesses containing air were confirmed by both horizontal beam radiography and surgery. Since ultrasound examination is frequently performed before radiography in patients thought to have abscesses, it is important to look for and recognize the sonographic appearance of an air-fluid level.

Hepatic hemangiomas are the most common benign tumors of the liver and commonly present as incidental findings on sonographic examination of the abdomen. To chart more precisely the natural course of the sonographic appearance of hepatic hemangiomas, 47 patients with 68 hemangiomas were rescanned 1-6 years after the initial study. Fifty-six lesions (82%) showed an identical appearance on follow-up study. However, 12 (18%) of the lesions had an appreciably changed sonographic appearance. Three lesions could not be found, seven were less obvious (less echogenic), one was larger, and one smaller. This study shows that once hemangiomas are identifiable sonographically in adults, they have reached a stable size and change in size or appearance only rarely. They do not continue to grow slowly over time. Furthermore, this study also confirms that the sonographic appearance in the appropriate patient can differentiate these hemangiomas relatively reliably from metastases.

An ultrasonographic pattern of mass lesions with strong central echoes appears to be specific for lesions of the luminal GI tract. Three lesions from different portions of the GI tract showing this appearance are presented. Although ultrasound is not the technique of choice in the diagnosis of lesions of the luminal gastrointestinal tract, it is sometimes preferable to perform ultrasound prior to barium studies, and hence it is important to recognize this characteristic appearance.

The ultrasonic appearance of Candida infection in the livers of immunosuppressed patients is quite characteristic. Cystic, target-like lesions were found in three patients receiving chemotherapy for myeloproliferative diseases. The computed tomographic appearance is less characteristic. A possible explanation for the appearance of these lesions is presented.

Real-time ultrasound was used as an aid in intrauterine transfusions for patients with Rh isoimmunization. It was preferred to fluoroscopy and x-ray control to identify the placental site and fetal abdomen and to direct the insertion and placement of the transfusion needle. The technique was used 22 times in 12 patients and resulted in increased efficiency and safety, including decreased radiation to the fetus.

Three case reports illustrate the changes in a distal acoustic interface after transmission of an ultrasonic beam through a tissue containing two different tissue velocities. The "break" created in the distal interface should be recognized and should not be interpreted as representing a pathologic change.

The "WES" triad -- that is, the demonstration of the gallbladder Wall, the Echo of the stone, and the acoustic Shadow -- permits the specific diagnosis of stones in a contracted gallbladder. This triad positively identifies the gallbladder and helps to differentiate the contracted gallbladder with stones from a loop of bowel containing gas.

With the routine use of sonography in the evaluation of suspected gallbladder disease, the familiarity of gallbladder duplication and its differential considerations are essential. Three cases are presented: one surgically proven duplication of the gallbladder, one case in which the sonographic findings were compatible with duplication of the gallbladder, and one surgically proven intraperitoneal fibrous band mimicking a gallbladder duplication. Gallstones were present in all cases and were confined to only one of the two lobes identified in each case. The gallstones did not communicate between individual gallbladder lobes despite multiple patient positions. Contraction of the non-stone-containing lobe was present in one nonfasting patient, which is probably the best indirect sign of a double gallbladder.

We used high-resolution real-time ultrasonography to examine the gallbladder in patients with signs and symptoms suggestive of gallbladder disease. Using this noninvasive technique, the physician can examine the gallbladder and related anatomy thoroughly in less than five minutes. The technique is much easier to learn and perform than gray-scale ultrasonography. In 313 patients in whom gallstones were later confirmed at cholecystectomy or autopsy, the ultrasound examination achieved an accuracy of 96 per cent in the evaluation of cholelithiasis. Five examinations gave false-negative results, one a definite false-positive result, and two possible false-positive results; six examinations were inadequate. The sensitivity of the method was 98 per cent, and the specificity was between 93.5 and 97.7 per cent. In 124 patients evaluated prospectively by means of both ultrasound and oral cholecystography, the ultrasound study revealed calculi in five patients in whom calculi were not demonstrated on an adequate oral cholecystogram. No calculus detected with oral cholecystography was missed by ultrasound. We believe that ultrasound should replace oral cholecystography as the first technique in evaluation of the patient with suspected gallbladder disease.

The authors present a series of 13 patients with intraocular melanomas imaged using high resolution Small Parts Ultrasonography. All patients underwent enucleation and subsequent histopathologic examination. On ultrasonography, patients were assessed for the presence of retinal detachment, choroidal excavation, rupture through Bruch’s membrane, retro-orbital fat shadowing, and acoustic texture. Correlation with histopathology demonstrated that using traditional criteria, the majority of rupture through Bruch’s membrane was missed due to the limits of instrument resolution. No patients with a homogeneous acoustic texture showed evidence of tumour necrosis or haemorrhage, while the vast majority of those with an inhomogeneous texture did. The authors suggest that high resolution small parts scanning may result in an alteration in the traditionally accepted criteria for the B-Scan diagnosis of choroidal melanoma.

"Ring-down" is an ultrasound artifact that appears as a solid streak or a series of parallel bands radiating away from abdominal gas collections. Using an in vitro system of bubbles in water or gelatin, it was found that the ring-down artifact originated from the center of a cluster of four bubbles (bubble tetrahedron), three on top and one nestled beneath. Entrapped between the bubbles is a horn- or bugle-shaped fluid collection that we theorize emits a continuous sound wave back to the transducer when struck by an ultrasound pulse. Electronic processing by the scanner converts this continuous sound wave into the series of bands seen in the ring-down artifact.

A high-resolution real-time ultrasound sector scanner was used in the evaluation of patients with suspected gallbladder disease. This technique is noninvasive, requires minimal preparation, and takes less than five minutes for a thorough examination of the gallbladder and related anatomy. In 17 months, 959 patients were examined for suspected gallbladder disease and the gallbladder was adequately visualized in all but 5 patients. Follow-up information was obtained from surgery in 153 cases. There were 132 true-positive studies, 15 true-negative, 5 false-negative and one-false positive study. In a correlative study with oral cholecystography, calculi were detected ultrasonically in 5 cases that had been missed on the oral cholecystogram.

A tubular collection of fluid in the pancreas seen on ultrasound was initially thought to represent a dilated pancreatic duct, and subsequently shown to be a pancreatic pseudocyst.

Previous demonstrations of distal displacement of interfaces deep to cystic structures have been based on only the slower speed of sound through the cystic structure, which has been postulated to cause an apparent discontinuity in the echo from the diaphragm deep to a cyst. The authors found cysts whose identification could not be explained by this theory because they were too small or the diaphragm was displaced in such a manner that the explanation would not hold true. They propose that, in addition to the slowing of the speed of sound through the cyst, refraction at the edge of the cyst can cause the apparent discontinuity. Since the machine does not distinguish the sound beam as having been refracted, the echo is displayed at the appropriate distance along the vector in the direction in which the transducer was pointing at the time. A computer simulation is used to confirm this theory.

Oligohydramnios and megacystis were demonstrated sonographically at a gestational age of 18 weeks. This was confirmed radiographically by direct intrauterine injection of contrast medium into the enlarged fetal bladder. The fetus was aborted. Autopsy confirmed prune-belly syndrome with megacystis secondary to urethral obstruction. This case demonstrates the ability of ultrasound to diagnose a significant structural fetal abnormality early enough to allow termination of the pregnancy.

Turner syndrome has been the only genetic abnormality reported in which intrauterine cystic hygromas occur. We have recently seen three patients in whom cystic hygromas were detected in utero, and which turned out to be due to Turner, Down, and Noonan syndromes respectively. As the finding of a fetal cystic hygroma occurs in a spectrum of genetic disorders, anatomic and cytogenetic studies are indicated for definitive diagnosis.

In order to determine if serial, noninvasive evaluation of polytetrafluoroethylene (PTFE) vascular access grafts could identify a subgroup of patients at risk for thrombosis, the authors studied flow characteristics, using duplex ultrasonic scanning, in 18 hemodialysis patients with forearm loop grafts. On average, five examinations were performed per patient over the 10-month study period. Seven episodes of thrombosis occurred in six patients. The mean Doppler flow in grafts that subsequently thrombosed was significantly lower than in those that did not (544 +/- 218 ml/min versus 843 +/- 391 ml/min, p less than 0.001). The interval from last examination to thrombosis ranged from 13 to 58 days. At a defined cut-off flow of 450 ml/min, this test yielded a sensitivity of 83% and a specificity of 75% for episodes of thrombosis occurring within 2 to 6 weeks. The authors conclude that episodes of thrombosis in PTFE arm loop grafts are usually preceded by significantly lower Doppler-measured flow than grafts that do not thrombose and that it may be possible, by this means, to identify grafts at risk.

Twenty-two liver hemangiomas, initially diagnosed using ultrasonography, were imaged with a Picker 0.15 Tesla super-conducting scanner in order to (1) determine the reliability of spin-echo (SE) signal intensity measurements and the calculated T1 and T2 values of both normal tissue and hemangiomas and (2) assess the characteristics of hemangiomas as visualized by a low-field magnetic resonance imaging unit. Reproducible measurements of T1 values and signal intensities are possible (r = 0.93-0.99) but T2 values are less reproducible (r = 0.79) and more variable. T1 values provide the best discrimination between hemangiomas and normal liver (99% successful classification) followed by the SE signal intensity differences (94%). Signal intensity ratios and contrast-to-noise ratios of lesions compared with liver are similar to those of other studies. Most small hemangiomas exhibit homogeneous signal intensity but larger lesions can be nonhomogeneous.