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Biomedical subjects

P F Hahn

Publications and source records attributed to P F Hahn.

At least 91 records · Page 5Linked to original sources
PubMed1992

Sclerotherapy of malignant pleural effusion through sonographically placed small-bore catheters.

Pleural sclerosis after drainage with a small-bore catheter was performed in 21 patients with malignant pleural effusions. Intrapleural catheters 7- to 24-French in size were placed by using sonographic guidance. Tetracycline (18 patients) and bleomycin (four patients) were used as sclerosing agents (one patient had both). Clinical and radiologic follow-up was available on all patients until they died (range, 2 weeks to 25 months; mean, 3.6 months). Pleural sclerosis was successful in 15 (71%) of 21 patients. Two patients in whom pleurodesis failed had pleural sclerosis repeated, with one success and one failure. All of the failures were in patients in whom the amount of chest-tube drainage was more than 100 ml/day. Pleurodesis with tetracycline was painful in six patients; no pain was associated with use of bleomycin. Small pneumothoraces developed in four patients at the time of chest-tube placement, without consequence. A superimposed infection that developed in a patient having continuous drainage of pleural fluid was successfully treated with antibiotics. Pleural sclerotherapy can be performed through sonographically placed small-bore catheters with results comparable to those seen with large-bore, surgically placed catheters.

Adult↗
PubMed1991

Malignant small bowel obstruction and ascites: not a contraindication to percutaneous gastrostomy.

Percutaneous gastrostomy (PG) with gastropexy was performed for relief of malignant small bowel obstruction in 12 patients with extensive ascites. Abdominal paracentesis was performed before PG in nine patients and after PG in one patient. Gastrostomy catheters were inserted without complication in all patients. Clinical follow up revealed that pericatheter leakage of ascitic fluid and skin excoriation occurred only in the three patients who did not have paracentesis performed before PG. No dislodgement of gastrostomy catheters occurred but mild peritonitis was noted in one patient. Our experience suggests that although in the past extensive ascites was a relative contraindication for PG, these patients can now be successfully treated with a combination of ultrasound-guided paracentesis to reduce pericatheter leakage of ascitic fluid, and gastropexy to prevent catheter dislodgement.

Abdomen↗
PubMed1991

Percutaneous contact dissolution of gallstones: complexity of radiologic care.

The clinical and technical considerations for successful gallstone dissolution with methyl tert-butyl ether (MTBE) are often underestimated. Patients are selected for MTBE therapy on the basis of a functioning gallbladder without evidence of acute inflammation or calcified stones at plain radiography. A transhepatic route is favored for percutaneous insertion of the cholecystostomy catheter because of the theoretic reduced frequency of bile leakage. MTBE is delivered manually through the catheter in a closed system, with dissolution times of 4-16 hours. After MTBE dissolution, residual debris in the gallbladder is present at follow-up sonography in up to 75% of patients. The high frequency of residual debris, the potential for stone recurrence, and the labor-intensive nature of MTBE therapy make its future uncertain, especially with the advent of laparoscopic cholecystectomy.

Cholelithiasis↗
PubMed1991

Benign and malignant adrenal masses: CT distinction with attenuation coefficients, size, and observer analysis.

In a retrospective study of adrenal masses evaluated with computed tomography (CT), lesion x-ray attenuation was compared with size and radiologists' interpretations in discriminating benign lesions from malignant ones. Unenhanced CT attenuation coefficient and size were analyzed electronically in 55 patients with 66 adrenal masses. There were 38 nonhyperfunctioning adenomas in 33 patients and 28 malignant masses in 22 patients. Primary extraadrenal malignancies were present in 45 of the 55 patients. Three blinded readers characterized the adrenal masses using a seven-point scale of certainty. Results were subjected to receiver operating characteristic (ROC) analysis. The mean CT attenuation coefficient for benign adrenal masses was -2.2 HU +/- 16.0 and was significantly different from the mean for malignant lesions (28.9 HU +/- 10.6). The area under the ROC curve for CT attenuation coefficients (0.91 +/- 0.04) was significantly larger than that for lesion size (0.84 +/- 0.05) or best observer interpretation (0.84 +/- 0.05). A threshold CT attenuation value of 0 HU had a sensitivity-to-specificity ratio of 47%:100% for characterizing benign adrenal masses, whereas a threshold attenuation of 10 HU had a ratio of 79%:96%.

Adrenal Gland Neoplasms↗
PubMed1991

Importance of daily rounds by the radiologist after interventional procedures of the abdomen and chest.

A prospective study was performed to evaluate the clinical utility of daily rounds by the radiologist for patients with indwelling catheters in the chest and abdomen, placed during interventional radiologic procedures. The 7-week evaluation included documentation of the number of patients seen, time spent with each per day, number of problems identified, management of these problems, and consultations for new cases generated by interaction with other staff. During the 268 visits to 37 patients, 59 catheter-related problems were identified; 17 (29%) required further intervention in the radiology department, and 42 (71%) were managed at the patient's bedside. Of the patients who were followed up, 22 (59%) had some catheter-related problem identified during their hospital stay. Daily rounds by the radiologist are an essential component of patient care after catheter-related interventional procedures and should be made by those who perform and understand the procedures.

Catheterization↗
PubMed1991

MR imaging of liver metastases at 1.5 T: similar contrast discrimination with T1- and T2-weighted pulse sequences.

The authors evaluated soft-tissue contrast on spin-echo (SE) proton density-weighted, SE T2-weighted, SE short-echo-time (TE) T1-weighted, and gradient-echo (GRE) images of 34 patients with known hepatic tumors who underwent high-field-strength (1.5-T) magnetic resonance imaging. For solid liver tumors, the difference in the mean lesion-liver contrast-to-noise ratios (C/Ns) with T1- (GRE and SE) and T2-weighted pulse sequences was not statistically significant (P greater than .05). For nonsolid liver tumors, the T2-weighted images provided significantly greater (P less than .05) mean lesion-liver C/N than T1-weighted GRE images. Mean liver signal-to-noise ratio was significantly greater on T1-weighted GRE (P less than .0001) and T1-weighted SE (P less than .05) images than on T2- and proton density-weighted images. Qualitative analysis of T1-weighted (SE and GRE) images and proton density- plus T2-weighted images showed that lesion conspicuity was similar in 25 of 32 patients (78%). The results suggest that liver tumor imaging at high field strength can be performed with short-TE T1-weighted (SE or GRE) or conventional T2-weighted pulse sequences.

Humans↗
PubMed1991

Focal nodular hyperplasia of the liver: MR findings in 35 proved cases.

MR images of 28 patients with 35 lesions of hepatic focal nodular hyperplasia were reviewed to determine the frequency of findings considered typical of this condition (isointensity on T1- and T2-weighted pulse sequences, a central hyperintense scar on T2-weighted images, and homogeneous signal intensity). Fifteen lesions were imaged at 0.6 T with T1- and T2-weighted spin-echo (SE) pulse sequences; 20 lesions were imaged at 1.5 T with T1-weighted SE and gradient-echo pulse sequences and T2-weighted SE pulse sequences. Diagnosis of focal nodular hyperplasia was made pathologically in 25 patients, with nuclear scintigraphy in four, and with follow-up imaging in six. Only seven lesions (20%) were isointense relative to normal liver on both T1- and T2-weighted images. On T1-weighted SE images, 21 lesions (60%) were isointense relative to normal liver, 12 (34%) were hypointense, and two (6%) were hyperintense. On T2-weighted SE images, 12 lesions (34%) were isointense and 23 (66%) were hyperintense relative to normal liver. A central scar was present in 17 lesions (49%) and was hypointense relative to the lesion on T1-weighted images and hyperintense on T2-weighted images. Twenty lesions (57%) were of homogeneous signal intensity throughout the lesion, except for the presence of a central scar. All three MR imaging characteristics were present in three cases (9%). We conclude that hepatic focal nodular hyperplasia has a wide range of signal intensity on MR imaging.

Adult↗
PubMed1991

Treatment of critically ill patients with sepsis of unknown cause: value of percutaneous cholecystostomy.

Because of the difficulty in diagnosing acute cholecystitis in critically ill patients with severe intercurrent illness by clinical and imaging methods or percutaneous aspiration of the gallbladder, a trial of percutaneous cholecystostomy was performed in 24 patients in the intensive-care unit with persistent, unexplained sepsis after a complete clinical, laboratory, and radiologic search showed no alternative source of infection. Persistent high fevers, despite antibiotic therapy, were present in all patients, with elevated WBC count in 18 patients, vague abdominal tenderness in 11, and septic shock requiring vasopressors in 15. Sonographically, all patients had distended, spherical gallbladders, six had gallstones, eight had wall thickening, three had pericholecystic fluid, and four had Murphy's sign. All patients were seen by a senior abdominal surgeon, who agreed to a trial of percutaneous cholecystostomy. Fourteen patients (58%) responded to percutaneous cholecystostomy, as evidenced by a decrease in WBC count, defervescence, and the ability to be weaned off vasopressors. Bile cultures were positive in four patients. Ten patients (42%) did not respond to percutaneous cholecystostomy; five eventually died of unrelated causes. A respiratory source of infection was eventually found in three of these 10 patients, with no proved source of infection in the remainder. No complications related to catheter insertion occurred in this group of patients. Bile leaks occurred in two patients when the percutaneous cholecystostomy catheter was removed, but without serious consequence. Our experience suggests that a lower threshold for performing percutaneous cholecystostomy in this difficult clinical subset of patients is worthwhile.

Acute Disease↗
PubMed1991

Differentiation between hemangiomas and metastases of the liver with ultrafast MR imaging: preliminary results with T2 calculations.

We studied the efficacy of T2 measurements at high field strength in distinguishing between liver hemangiomas and hepatic metastases when an ultrafast (single-excitation) MR imaging technique is used. Fourteen patients with known liver tumors were imaged in a 2.0-T prototype ultrafast MR scanner with a spin-echo (infinite TR and TE of 30-340 msec) pulse sequence. Each image was obtained with a total data acquisition time of 20 msec. T2 calculations for hepatic metastases (n = 6) showed a mean of 79.3 +/- 13.5 msec, whereas hemangiomas (n = 8) showed a T2 of 139.8 +/- 18.8 msec (p less than .0001). T2 values of lesions had a smaller relative standard deviation than previously reported, and the range of T2 values of hemangiomas (119-181 msec) and metastases (68-103 msec) did not overlap. Our preliminary results suggest that T2 calculations with ultrafast MR imaging may be useful for differentiating hemangiomas from metastases. We hypothesize that T2 values obtained from ultrafast MR images are more reliable than those obtained from conventional MR images, primarily because of the elimination of T1 information and effects of motion on image signal intensity.

Carcinoid Tumor↗
PubMed1991

Percutaneous dilatation of benign biliary strictures: single-session therapy with general anesthesia.

Percutaneous biliary stricture dilatation (PBSD) is an uncomfortable procedure for patients that presently requires multiple dilatation sessions spread over many days. We evaluated the use of general anesthesia to enable PBSD to be performed in a single sitting in 14 patients with benign biliary strictures (11 anastomotic and three iatrogenic strictures). Four patients had multiple strictures, and the other 10 had a single stricture. Strictures were documented by transhepatic cholangiography (11 patients) or T-tube cholangiography (three); quantitative biliary perfusion studies were additionally performed in seven cases. Dilatation was performed transhepatically in 11 patients and via a T-tube track in three. Balloons ranged from 8 to 12 mm in diameter and were manually inflated for 3 min with an average of five inflations per stricture. Stenting catheters were left across the strictured areas in all patients for 6-21 days (mean, 10 days) before removal. The mean duration of hospital stay for all patients was 5.7 days, which could further be divided into means of 3.6 days (range, 1-6 days) for 11 patients without complications and 13.7 days (range, 13-14 days) for three patients who had complications. Complications included cholangitis; liver hematoma (which resolved with conservative therapy in both cases); and pseudoaneurysm of the hepatic artery, which necessitated angiographic embolization. PBSD achieved long-term patency in 13 (93%) of 14 patients with a follow-up period of 2.0 to 5.5 years (mean, 3.2 years). A stricture recurred in one patient 1.5 years after dilatation. We conclude that PBSD with the patient under general anesthesia can be performed in a single visit to the radiology department with excellent long-term patency rates, a shorter hospital stay, and a pain-free procedure for the patient.

Adolescent↗
PubMed1990

Clinical application of superparamagnetic iron oxide to MR imaging of tissue perfusion in vascular liver tumors.

Previous studies of AMI-25, a particulate iron oxide magnetic resonance contrast agent, imaged liver tumors 1 or more hours after injection, in the retention phase after complete clearance of AMI-25 from the circulation. In the present study, imaging was performed in the distribution phase, during the first 12 minutes after injection while contrast agent remain in circulation, and these images were compared with those obtained in the retention phase. Nineteen patients with cancer were studied, including 15 imaged during the distribution phase. T2-weighted distribution phase images demonstrated 90% of the lesions detected by means of T2-weighted retention phase images, showed a 3.5-fold increase in contrast-to-noise ratio over images obtained before administration of AMI-25, and increased diagnostic confidence by reducing signal from small intrahepatic blood vessels. Distribution phase images showed little contrast agent uptake by cancer tissue. Both distribution and retention phase images demonstrated greater contrast agent uptake by hemangiomas than by malignant neoplasms (P less than .01). The use of both distribution phase and retention phase AMI-25-enhanced images offers improved diagnostic accuracy in the detection and characterization of focal liver lesions.

Adenocarcinoma↗
PubMed1990

First clinical trial of a new superparamagnetic iron oxide for use as an oral gastrointestinal contrast agent in MR imaging.

The authors report the results of preclinical testing and initial clinical application of a superparamagnetic iron oxide specifically prepared as a contrast agent for magnetic resonance (MR) imaging of the gastrointestinal tract. MR imaging was performed at 0.6 and 1.5 T in 15 volunteers. Images of the upper abdomen and pelvis were obtained before and after ingestion of the contrast material at doses of 22.5-225.0 mg of iron in 600-900 L. Two readers scored the images. Delivery of contrast material into the proximal and distal small bowel, with obvious loss of signal intensity (T2 enhancement), was achieved in all subjects. Enhanced images showed improved delineation of the head and tail of the pancreas, anterior margins of the kidneys, and paraaortic region. The contrast agent did not generate artifacts, an improvement over prototype formulations evaluated previously in animals. Except for a brief episode of diarrhea in five subjects, the agent was well tolerated. Use of this contrast agent improved the diagnostic quality of abdominal MR images by enabling the distinction of the bowel from nonbowel structures at concentrations that did not produce image distortion.

Adult↗
PubMed1990

Occlusion of biliary endoprostheses: presentation and management.

A retrospective review of 20 cases of endoprosthesis occlusion in 17 patients was performed. The average length of stent patency before occlusion was 3.7 months. Clinical manifestations included one or a combination of the following: cholangitis (n = 17), jaundice (n = 9), and leakage of bile or purulent material from the percutaneous insertion site (n = 6). Eighteen of 20 episodes of endoprosthesis occlusion were successfully managed with normalization of biochemical parameters and alleviation of clinical manifestations. No therapy was attempted in two episodes of stent occlusion due to widespread metastatic disease. All 17 patients received intravenous fluid replacement and broad-spectrum antibiotic therapy. This was sufficient therapy to relieve symptoms in two cases of occlusion. Occluded stents were removed in the other 16 patients by means of radiologic (n = 10) or endoscopic (n = 6) methods. After the acute septic episode had subsided (2-5 days; mean, 3 days), new endoprostheses were percutaneously inserted in 10 cases of occlusion, long-term internal-external catheters were placed in five, and surgical bypass was performed in one. The authors conclude that endoprosthesis occlusion should not be considered a terminal event in patients with malignant biliary disease.

Aged↗
PubMed1990

Percutaneous gastrostomy with gastropexy: experience in 125 patients.

We report our experience with radiologically guided percutaneous tube gastrostomy in 125 patients by using a gastropexy technique in which the anterior gastric wall is nonsurgically sutured to the anterior abdominal wall with percutaneously placed T-fasteners before catheter insertion. Short-term follow-up of up to 2 weeks was available in all patients. In 63 patients, long-term follow-up (greater than 4 weeks; average, 3.5 months; maximum, 1 year) was available. Catheter placement was successful in 124 (99%) of 125 patients, including three patients with anatomic changes after Bilroth II hemigastrectomy and two patients with failed endoscopic attempts. There were no deaths related to the procedure, and no patients required surgical intervention for complications attributable to the gastrostomy procedure. The 30-day mortality rate was 11% (n = 7). These deaths were due to cardiorespiratory arrest and were not attributable to the gastrostomy procedure. Major complications occurred in 1.6% (n = 1) and minor complications in 9.5% (n = 6). These results indicate that percutaneous gastrostomy with gastropexy is a safe and effective technique for placement of catheters in the stomach.

Adult↗
PubMed1990

Differentiation between small hepatic hemangiomas and metastases on MR images: importance of size-specific quantitative criteria.

We studied the feasibility of using MR imaging at 0.6 T to differentiate small hepatic hemangiomas from small metastases on the basis of quantitative criteria. Ninety-two liver masses up to 5 cm in diameter, including 51 proved hemangiomas (mean, 1.9 +/- 1.1 cm) and 41 proved metastases (mean, 1.9 +/- 1.2 cm) were analyzed. Lesions were divided into three groups on the basis of size (less than or equal to 1 cm, greater than 1- less than or equal to 2 cm, greater than 2- less than or equal to 5 cm). The ability to distinguish hemangiomas from metastases was examined by using differences in lesion/liver signal-intensity ratio (SIR) and contrast-to-noise ratio (CNR) on T2-weighted images (SE 2350/180). Receiver-operating-characteristic analysis for all lesions grouped together showed that differentiation based on SIR was superior to that based on CNR (p less than .05). The mean SIR of hemangioma and the difference between mean SIRs of hemangioma and metastasis decreased with lesion size (greater than 2- less than or equal to 5 cm: 6.11 +/- 2.61 vs 2.30 +/- 1.22; greater than 1- less than or equal to 2 cm: 4.47 +/- 1.56 vs 2.40 +/- 0.73; less than or equal to 1 cm: 3.59 +/- 0.92 vs 2.01 +/- 0.52). However, in each size group, the difference between the mean SIR of hemangioma and metastasis was statistically significant (p less than .0001). These observations suggest that MR imaging is useful in differentiating small hepatic hemangiomas from small metastases and suggest the need for establishing size-specific quantitative criteria for tissue characterization.

Diagnosis, Differential↗