Biomedical subjects
Publications and source records attributed to A A Nemcek.
The authors describe computed tomographic (CT) and magnetic resonance (MR) imaging of coexistent anomalies of the inferior vena cava and renal venous system. These were particularly relevant due to the presence of a renal neoplasm which invaded an anomalous renal vein.
Pregnancy is a contraindication to extracorporeal shock wave lithotripsy (ESWL) because of its possible harm to the embryo or fetus caused by shock waves or ionizing radiation. In this study timed-pregnant rats were subjected to shock waves early in gestation using a lithotriptor having ultrasound imaging. In a pilot group undergoing immediate laparotomy, it was determined to what extent the pelvic structures were effected. Then a test group was exposed to shock waves and carried to near term pregnancy along with an identical group of pregnant, sham procedure rats. A laparotomy all were inspected for fetal viability, fetal abnormalities, and maternal organ damage. Fetuses located nearest the focal area of maximum shock wave energy showed lower mean weight than controls. There was no recognizable gross or microscopic fetal damage.
Transjugular intrahepatic portosystemic stent-shunt placement has shown great promise as a means of protal decompression in patients with severe portal hypertension. Passage of a needle from the hepatic venous system into the portal venous system during this procedure may be technically difficult; while it would be advantageous to precisely target the portal vein, most methods of localization are themselves technically difficult, risky, or time-consuming. The authors describe a method of localization of the portal vein that, when feasible, appears to be both safe and technically simple. This method involves percutaneous catheterization of a paraumbilical portosystemic collateral vein under sonographic guidance.
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Aberrant right hepatic ducts are the most common biliary tract anomaly and are particularly susceptible to injury at cholecystectomy because of their critical location. The authors report radiologic diagnosis and therapy in five cases of inadvertent ligation of this duct at cholecystectomy. The diagnosis was unsuspected prior to the radiologic studies in each patient. Four patients experienced recurrent cholangitis; one patient had chronic pain as the only symptom. Prior to diagnosis, the duration of symptoms ranged from 2 weeks to 126 months. Findings at ultrasound, computed tomography, and percutaneous transhepatic cholangiography with differential biliary pressures helped establish the diagnosis in each patient. Findings at endoscopic retrograde cholangiopancreatography were nondiagnostic in four patients. Percutaneous biliary drainage provided palliation of symptoms, improved each patient's condition prior to reconstructive surgery, and provided an intraoperative landmark for the surgeon. Two patients had associated bilomas, one of which was infected and was drained percutaneously. All patients survived and recovered without further complications.
Uterine arteriovenous malformations are rare lesions that can cause massive vaginal bleeding and spontaneous abortions. The majority are either congenital or related to gestational trophoblastic disease. Hysterectomy has been the treatment with symptomatic uterine arteriovenous malformations by means of transcatheter embolization; three of the lesions were related to gestational trophoblastic disease and one was congenital. All were supplied by the uterine arteries that were subselectively embolized with particulate material. This resulted in prompt cessation of uterine hemorrhage. There were no complications, and one pregnancy was achieved. The three other women have normal menstruation and no recurrence of bleeding at follow-up 10-48 months after treatment. On the basis of this experience and that of others, embolotherapy should be the treatment of first choice in these lesions, as it appears safe and effective. Additionally, uterine function is preserved in patients who are usually reproductively active.
Percutaneous cholecystostomy is now commonly performed for the diagnosis and treatment of gallbladder and biliary disorders. The optimal method and route of percutaneous cholecystostomy catheter placement, however, remain controversial and may depend on the indication for the procedure. The ability to predict traversal of the extraperitoneal plane of fixation ("bare area") between the liver and gallbladder with a transhepatic approach was investigated. With sonographic guidance, 21 transhepatic catheterizations were attempted: 19 in cadavers and two in patients who subsequently underwent cholecystectomy. In all cases, 8-F or 5-F self-retaining catheters were used. At autopsy or surgery, the catheter course and gallbladder puncture site were evaluated. Of 21 punctures, 19 (90%) were transhepatic and two (10%) were transperitoneal. Among the 19 transhepatic punctures, eight catheters (42%) traversed the bare area, while 11 (58%) entered the free gallbladder wall adjacent to the serosal attachment. There were four instances of guide-wire dislodgment during catheter placement; all occurred following puncture of the free wall of the gallbladder. No guide-wire dislodgment occurred when the bare area was transversed. Transhepatic gallbladder puncture does not prevent puncture of the free gallbladder surface. However, the liver and bare area do seem to provide guide-wire stability during catheter placement.
The authors describe a patient with a posttraumatic intrahepatic false aneurysm. In this case, transcatheter embolization was not possible because of previous right hepatic artery embolization. To avoid the morbidity associated with surgery, direct percutaneous puncture of the pseudoaneurysm was performed under fluoroscopic guidance to permit embolization with Gianturco coils. Direct percutaneous embolization of intrahepatic aneurysms and pseudoaneurysms can be a safe and effective alternative to surgery when transcatheter techniques are not feasible.
The ability to ablate atheroma without generating heat makes the excimer laser wavelength a promising intraluminal technique for the treatment of arterial occlusive disease. This series reviews a preliminary experience treating patients with superficial femoral arterial disease admitted with limb-threatening ischemia or claudication. Twenty-six diseased superficial femoral arteries (5 stenotic and 21 occluded) were treated in 23 consecutive patients. Patients with claudication (18) reluctant to undergo bypass or with limb-threatening ischemia (8) at extremely high risk for surgery were included. There were 10 men and 13 women with a mean age of 67 years. A 308 nm excimer laser with an over-the-wire catheter (19) or balloon-centered end-on catheter (7) was used followed by balloon angioplasty. Twenty-four procedures were performed percutaneously, and two were performed with the vessel open in the operating room. Technical success, defined as disobliteration confirmed by angiography and greater than 0.15 increase of the ankle/brachial index, was achieved in 15 of 26. Eleven of 21 occlusions (52%) and four of five stenoses (80%) were opened. Only two of 11 lesions longer than 10 cm were successfully treated. Unsuccessful attempts (technical failure) occurred in 11 of 26 patients and resulted in four elective and one emergency femoral-popliteal bypass. Five patients were discharged with their claudication unchanged, and one had an elective amputation. Six arterial perforations with three arteriovenous fistulas occurred, all resolved without operation. No unanticipated limb loss occurred. In the 15 successful cases, the mean ankle/brachial index increase was 0.34. Seven (47%) of these 15 remain patent with a mean follow-up of 9.5 months (1.5 to 14 months).(ABSTRACT TRUNCATED AT 250 WORDS)
The usual appearance of the postoperative chest radiograph in patients after coronary artery bypass surgery is well known. The article describes an unusual case with development of a right anterior mediastinal mass after bypass surgery with internal mammary artery grafts. This mediastinal mass, initially detected on a chest radiograph, was confirmed by contrast-enhanced chest CT to be intrathoracic fat from the right internal mammary artery pedicle.
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Seven patients with duodenal diverticulitis were evaluated by computed tomography (CT) and various other abdominal imaging techniques. The series included four men and three women who ranged in age from 47 to 84 yr (mean: 65 yr). They had presented with epigastric or periumbilical pain, low-grade fever, leukocytosis, and loss of appetite and weight due to postprandial cramps or vomiting. In each instance, the abdominal CT examination proved crucial in the diagnosis of duodenal diverticulitis, with contained perforation or inflammatory changes involving the adjacent structures. Five patients underwent laparotomy while two others were treated conservatively with antibiotics and/or percutaneous drainage of peridiverticular abscess. The clinical and radiological features of this uncommon entity are herein described, along with a brief review of the medical literature regarding the current approach to its diagnosis and management.
Several factors may affect the fragmentation of gallstones by lithotripsy. We hypothesized that stone volume is an important determinant of degree of fragmentation, while number of stones is less important. The volume of 30 single stones was measured in vitro by water immersion. Thirty sets of multiple stones were matched with single stones of similar volumes. The stones were subjected to 750 shock waves (18 kV) with the Dornier MPL 9000 lithotripter. Degree of fragmentation was assessed by passing fragments through sieves of 1, 2, and 4 mm and recording percentage of stone weight which passed through each sieve. The mean percentage of stone weight passing through sieves of 1, 2, and 4 mm for single stones was 38.2, 49.4, and 59.8. The corresponding values for multiple stones were 46.4, 61.3, and 75.4. These values were not significantly different at P less than or equal to 0.05. Thus, there was no significant difference in fragmentation between single and multiple stones when their volumes were similar. The mean volume of stones with 100% of fragments less than 4 mm (0.80 +/- 0.05 cc) was significantly less than that of stones with fragments greater than 4 mm (1.95 +/- 0.14 cc) (P less than 0.0001). There was a significant inverse linear correlation between stone volume and degree of fragmentation (r = -0.65). We conclude that stone volume is an important determinant of degree of fragmentation and may be the most important criterion in selecting patients for lithotripsy. In this in vitro setting, stone number alone had no effect on degree of stone fragmentation.
Currently, the only available method to measure perfluorooctylbromide (PFOB) in tissues requires its extraction with a solvent followed by gas chromatography. Not only is this method invasive, but it cannot be validated because the amount of unextracted PFOB is unknown. Using a cylindrical CT phantom with eight wells in the wall filled with bromine (Br) standards, an in vivo method to measure PFOB tissue concentration was developed. Neutron activation analysis (NAA) was used to calibrate and validate the phantom since NAA allows the quantification of Br by making Br radioactive without the need for extraction. Once NAA was validated for PFOB, the phantom was calibrated using 80 rats and tested using 20 rats relative NAA. The phantom produced linear correlation between CT number and known PFOB concentrations with r = 0.998. After its calibration with NAA, the CT method produced a linear correlation between tissue PFOB concentration determined by CT and NAA near the line of identity with an r = 0.984, thus allowing the determination of PFOB tissue content in vivo noninvasively.
We report on the sonographic (US) and magnetic resonance imaging (MRI) appearance of a mixed sex-cord stromal tumor of the testis. The case is notable due to its rarity, its unusual imaging characteristics as correlated with pathology, and the ability of MRI, in this particular case, to give more complete information than US as to the character of the lesion.
Although alternatives to cholecystectomy are now available to treat patients with gallstones, the primary treatment of gallstone disease remains surgical. It is therefore important to distinguish those patients who would benefit most from nonoperative therapy of gallstones from those who require cholecystectomy while ensuring patient safety. Current criteria for selection of patients for extracorporeal shock-wave lithotripsy (ESWL) are presented herein. In addition, preliminary results from recent in vitro experiments with human gallstones obtained at cholecystectomy are outlined. The current criteria for selection of patients for treatment with ESWL are similar to those used in the initial German experience. They appear to ensure patient safety, but the actual conditions that predict successful treatment of gallstones by ESWL are not yet known, since the clinical and in vitro studies which will define the patient and stone characteristics that predict a successful treatment outcome are still in progress. Thus, current criteria should be considered guidelines for treatment which will most certainly be modified as experience is gained with ESWL.
Topographic relationships among the gallbladder, liver, hepatic flexure of the colon, right hemidiaphragm, and anterolateral peritoneal reflection were evaluated with computed tomography in 75 patients with biopsy-proved cirrhosis and in 200 control subjects to determine the effect of cirrhotic liver morphology on the anatomy of the right upper quadrant of the abdomen. Interposition of the colon between the liver and anterolateral abdominal wall and/or diaphragm was seen in 18 of the 75 (24%) cirrhotic patients and in six of the 200 (3%) control subjects. There was a strong correlation among gallbladder malposition, colonic interposition, and a ratio of transverse caudate lobe width to right lobe width (C/RL) exceeding 0.60. Patients with cirrhosis, colonic interposition, and gallbladder malposition had a mean C/RL of 0.62, compared with a mean of 0.50 for cirrhotic patients without interposition (P less than .0001). The mean C/RL for control subjects without interposition was 0.43, as compared with 0.69 for control subjects with interposition (P less than .01). These acquired malpositions of the colon and gallbladder may pose a diagnostic dilemma and increase the risk of inadvertent injury during percutaneous liver biopsy, interventional biliary tract procedures, and laparotomy.