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Peter R Mueller

Publications and source records attributed to Peter R Mueller.

At least 37 records · Page 2Linked to original sources
PubMed2005

Image-guided percutaneous radiofrequency ablation and incidence of post-radiofrequency ablation syndrome: prospective survey.

PURPOSE: To evaluate prospectively the incidence of post-radiofrequency (RF) ablation syndrome and determine its impact on the quality of life in the 10 days after percutaneous RF ablation. MATERIALS AND METHODS: This study was approved by the institutional review board and was HIPAA compliant. Informed consent was obtained for this survey in all patients by the interventional nurse coordinators. Thirty-six patients (20 men, 16 women; mean age, 69.3 years; range, 40-88 years) underwent RF ablation for 26 liver tumors and 17 renal tumors. Twenty control patients (11 men, nine women; mean age, 60.8 years; range, 35-76 years) underwent biopsy of focal liver lesions or renal lesions. With a standardized questionnaire, a telephone survey was conducted on days 1, 3, 5, and 10 after RF ablation or biopsy. The symptoms and interference with lifestyle were documented prospectively with a numeric intensity scale by using grades 0-10. Statistical analysis with Fisher exact test and analysis of variance was performed. RESULTS: After RF ablation, 15 (42%) patients developed low-grade fever (P < .001), 29 (81%) had flulike symptoms (P < .001), and four were asymptomatic. Symptoms peaked on day 3 and mainly resolved by day 10. Twelve (33%) patients had complete post-RF ablation syndrome: fever and flulike symptoms (P = .005). Flulike symptoms were more prolonged when they were accompanied with fever, peaked on day 5, and resolved more quickly for patients with renal lesions than they did for patients with liver lesions. Four patients had persistent fever caused by pneumonia (n = 2), pleural effusion and atelectasis (n = 1), or liver abscess (n = 1). No control patients developed both fever and flulike symptoms. Post-RF ablation patients with symptoms experienced significantly greater pain and interference with general and work activities, which peaked on day 1, than did control patients (P = .01 [pain], P < .001 [general and work activities]). CONCLUSION: Complete post-RF ablation syndrome occurs in approximately one-third of patients but is self-limiting within 10 days after the procedure. Persistent or late-onset fever may indicate concurrent infection elsewhere or possible abscess formation. SUPPLEMENTAL MATERIAL: radiology.rsnajnls.org/cgi/content/full/237/3/1097/DC1

Adult↗
PubMed2005

Percutaneous cholecystostomy catheter removal and incidence of clinically significant bile leaks: a clinical approach to catheter management.

OBJECTIVE: We sought to determine the incidence of bile leaks upon removal of small-bore percutaneous cholecystostomy catheters and to evaluate clinical and imaging guidelines to ensure safe catheter removal. MATERIALS AND METHODS: A retrospective evaluation of all gallbladder drainages performed over a 5-year period revealed 163 patients (range, 7-98 years) who underwent percutaneous cholecystostomy catheter placement. Medical records and imaging studies were reviewed to assess the events at catheter removal (e.g., inadvertent removal, controlled removal with cholangiography without tract imaging, or controlled removal with cholangiography with tract imaging) and the incidence of major and minor bile leaks. RESULTS: The events at catheter removal were assessed in 66 patients. Group 1 was 45 patients whose catheters were removed after a minimum of approximately 3 weeks with a cholangiogram that established cystic and common duct patency and no imaging of the tract. Catheters were not removed until the patient recovered from acute illnesses that contributed to acalculous cholecystitis. Group 2 was 11 patients managed similarly to group 1 except that tract imaging was performed at catheter removal. Group 3 was 10 patients whose tubes came out inadvertently without cholangiogram or tract imaging. Two major (group 2 and group 3) and two minor (group 2) bile leaks occurred. No bile leaks occurred in group 1 (p = 0.006). CONCLUSION: Major bile leaks occurred in 3% of patients, and minor leaks occurred with equal frequency. Tract imaging may not be necessary in patients with small-bore gallbladder catheters who have recovered from critical illness, show patent cystic and common ducts, and have had catheters for 3-6 weeks.

Adolescent↗
PubMed2005

Radiofrequency ablation of renal cell carcinoma: part 1, Indications, results, and role in patient management over a 6-year period and ablation of 100 tumors.

OBJECTIVE: The objectives of our article are to review our experience with radiofrequency ablation of renal cell carcinoma and to assess size and location as predictors of the ability to achieve complete necrosis by imaging criteria. MATERIALS AND METHODS: Over a 6-year period, 100 renal tumors in 85 patients underwent radiofrequency ablation at a single institution. The absence of enhancement on CT or MRI after radiofrequency ablation was interpreted as complete coagulation necrosis. Results were analyzed by tumor size and location using multivariate analysis. A p value of 0.05 or less was considered significant. RESULTS: All 52 small (3 cm) and all 68 exophytic tumors underwent complete necrosis regardless of size, although many large tumors (> 3 cm) required a second ablation session. Using multivariate analysis, we found that both small size (p < 0.0001) and noncentral location (p = 0.0049) proved to be independent predictors of complete necrosis after a single ablation session. Location was a significant predictor (p = 0.015) of complete necrosis after any number of sessions, whereas size showed a strong trend (p = 0.059) toward predicting success after any number of sessions. Complications were either self-limited or readily treated and included hemorrhage (major, n = 2; minor, n = 3), inflammatory track mass (n = 1), transient lumbar plexus pain (n = 2), ureteral injury (n = 2), and skin burns (n = 1). CONCLUSION: Radiofrequency ablation is a promising minimally invasive therapy for renal cell carcinoma in patients who are not good operative candidates. Small size and noncentral location are favorable tumor characteristics, although large tumors can sometimes be successfully treated with multiple ablation sessions.

Aged↗
PubMed2005

Radiofrequency ablation of renal cell carcinoma: part 2, Lessons learned with ablation of 100 tumors.

OBJECTIVE: The objective of our study was to review radiofrequency ablation of 100 renal tumors and lessons learned with respect to electrode approach, effects on collecting system, bowel proximity, and patterns of residual disease. MATERIALS AND METHODS: Over 6 years, 100 renal tumors in 85 patients underwent radiofrequency ablation. Images were reviewed to determine the following: effect of initial electrode approach at and parallel to the tumor-kidney interface; effect of collecting system proximity to the tumor and to the zone of ablation; bowel proximity to the tumor and strategies to protect bowel; patterns of residual disease; and approaches at subsequent sessions. RESULTS: The initial placement of the electrode at and parallel to the tumor-kidney interface did not result in significantly fewer overlapping ablations (p = 0.91) or a lower rate of residual disease (p = 0.86). Direct contiguity of tumor or zone of ablation to the collecting system did not increase the complication rate. However, obscuration of calyces by a central tumor was a significant predictor of collecting system hemorrhage necessitating treatment (p < 0.001) seen in three of nine tumors obscuring calyces. Clinically significant urine leaks were rare (1/100) and related to downstream obstruction. There were no bowel complications despite the fact that 27 of the tumors were within 1 cm of bowel. Protective strategies progressed from reliance on electrode positioning to hydrodissection. Residual patterns were predominantly nodules or crescents, and straight electrodes were commonly used to approach residual disease. CONCLUSION: Initial electrode position at and parallel to the tumor-kidney interface does not result in less difficult or more successful ablations. Contiguity of tumor or zone of ablation to the collecting system does not increase the risk of complications, but obscuration of calyces does. Bowel complications are rare, and protection with hydrodissection is becoming more common. Residual tumor presents as nodules or crescents of persistent enhancement.

Aged↗
PubMed2004

Autoimmune pancreatitis: imaging features.

PURPOSE: To retrospectively determine imaging findings in patients with autoimmune pancreatitis. MATERIALS AND METHODS: Twenty-nine patients (25 male and four female; mean age, 56 years; range, 15-82 years) with histopathologic diagnosis of autoimmune pancreatitis were examined. Data were reviewed by two radiologists in consensus. Imaging findings for review included those from helical computed tomography (CT), 25 patients; magnetic resonance (MR) imaging with MR cholangiopancreatography (MRCP), four patients; endoscopic ultrasonography (US), 21 patients; endoscopic retrograde cholangiopancreatography (ERCP), 19 patients; and percutaneous transhepatic cholangiography, one patient. Images were analyzed for appearances of pancreas, biliary and pancreatic ducts, and other findings, such as peripancreatic inflammation, encasement of vessels, mass effect, pancreatic calcification, peripancreatic nodes, and peripancreatic fluid collection. Follow-up images were available in nine patients. Serologic markers such as serum immunoglobulin G (IgG) and antinuclear antibody levels were available in 12 patients. RESULTS: CT showed diffuse (n = 14) and focal (n = 7) enlargement of pancreas. Seven patients had minimal peripancreatic stranding, with lack of vascular encasement, calcification, or peripancreatic fluid collection. Nine patients had enlarged peripancreatic lymph nodes. MR imaging showed focal (n = 2) and diffuse (n = 2) enlargement with rimlike enhancement in one. MRCP revealed pancreatic duct strictures in two and sclerosing cholangitis-like appearance in one. Endoscopic US showed diffuse enlargement of pancreas with altered echotexture in 13 patients and focal mass in the head in six. ERCP showed stricture of distal common bile duct in 12 patients, irregular narrowing of intrahepatic ducts in six, diffuse irregular narrowing of pancreatic duct in nine, and focal stricture of proximal pancreatic duct in six. Serologic markers showed increased IgG and antinuclear antibody levels in seven of 12 patients. At follow-up, CT abnormalities and common bile duct strictures resolved after steroid therapy in three patients. CONCLUSION: Features that suggest autoimmune pancreatitis include focal or diffuse pancreatic enlargement, with minimal peripancreatic inflammation and absence of vascular encasement or calcification at CT and endoscopic US, and diffuse irregular narrowing of main pancreatic duct, with associated multiple biliary strictures at ERCP.

Adolescent↗
PubMed2004

Intraoperative US in patients undergoing surgery for liver neoplasms: comparison with MR imaging.

PURPOSE: To retrospectively compare intraoperative ultrasonography (US) and preoperative magnetic resonance (MR) imaging with contrast material enhancement for the depiction of liver lesions in patients undergoing hepatic resection. MATERIALS AND METHODS: A radiologist (D.V.S.) and a surgeon (K.K.T.) retrospectively identified 79 patients (36 female and 43 male patients; age range, 10-78 years; mean age, 57 years) who had undergone surgical resection for primary liver tumor or metastasis and had also undergone preoperative contrast-enhanced MR imaging within 6 weeks before surgery. MR imaging was performed with a 1.5-T system. Dedicated intraoperative US of the liver was performed or supervised by a gastrointestinal radiologist using a 7.5-MHz linear-array transducer, after adequate hepatic mobilization by the surgeon. Histopathologic evaluation of the 159 resected hepatic lesions served as the reference standard. The lesion distribution included colon cancer metastasis (n = 122), hepatocellular carcinoma (n = 23), cholangiocarcinoma (n = 6), cavernous hemangioma (n = 4), focal nodular hyperplasia (n = 2), hamartoma (n = 1), and metastatic embryonal sarcoma (n = 1). RESULTS: Of 159 lesions, 138 (86.7%) were identified at both MR imaging and intraoperative US. Twelve additional lesions (7.5%) in 10 patients were detected only at intraoperative US (eight metastases, one hepatocellular carcinoma, one cholangiocarcinoma, one hemangioma, and one biliary hamartoma). Both modalities failed to depict nine lesions (5.6%) (four metastases, four hepatocellular carcinomas, and one cholangiocarcinoma). The sensitivities of MR imaging and intraoperative US for liver lesion depiction were 86.7% and 94.3%, respectively. Surgical management was altered on the basis of the intraoperative US findings in only three of 10 patients (4%). CONCLUSION: Contrast-enhanced MR imaging is as sensitive as intraoperative US in depicting liver lesions before hepatic resection.

Adolescent↗
PubMed2004

Acute pancreatitis: the role of imaging and interventional radiology.

Acute pancreatitis can manifest as a benign condition with minimal abdominal pain and hyperamylasemia or can have a fulminant course, which can be life-threatening usually due to the development of infected pancreatic necrosis, and multisystem organ failure. Fortunately, 70-80% of patients with acute pancreatitis have a benign self-limiting course (figs. 1, 2, 4). The initial 24-48 hours after the initial diagnosis is usually the period that determines the subsequent course, and for many of the 20-30% of patients who subsequently have a fulminant course, this becomes apparent within this time frame. With reference to long-term outcome following acute pancreatitis, most cases recover without long-term sequelae with only a minority of cases progressing to chronic pancreatitis. In the initial management of acute pancreatitis, assessment of metabolic disturbances and systemic organ dysfunction is critical. However, the advent and continued refinement of cross-sectional imaging modalities over the past two decades has led to a prominent role for diagnostic imaging in assessing acute pancreatitis. Furthermore, these cross-sectional imaging modalities have enabled the development of diagnostic and therapeutic interventional techniques in the hands of radiologists. In this article we review the diagnostic features of acute pancreatitis, the clinical staging systems, complications and the role of imaging. The role of interventional radiology techniques in the management of acute pancreatitis will be discussed as well as potential complications associated with these treatments.

Acute Disease↗
PubMed2004

Haemolysis, elevated liver enzymes and low platelets syndrome: ultrasound and magnetic resonance imaging findings in the liver.

We describe the imaging findings of the HELLP (haemolysis, elevated liver enzymes and low platelets) syndrome in a gravid 36-year-old-woman who presented at 19.5 weeks gestation with severe right upper quadrant pain. Ultrasound findings suggested a focal hyperechoic liver lesion suggesting pregnancy-related hepatopathy prior to development of biochemical signs of HELLP syndrome. Within 3 days, the patient developed characteristic clinical and laboratory evidence of the HELLP syndrome. MR imaging at this time demonstrated localized hepatic ischaemia, further strengthening the diagnosis of HELLP syndrome.

Adult↗
PubMed2004

Pheochromocytoma: an imaging chameleon.

Pheochromocytomas are rare catecholamine-secreting tumors with many clinical and imaging manifestations. They may produce overwhelming cardiovascular crises if the diagnosis is not made or if appropriate treatment is delayed. It is thus important to recognize both their characteristic and atypical imaging appearances. Pheochromocytomas are encountered, sometimes unexpectedly, across a range of imaging modalities. They are characteristically solid, hypervascular masses with high signal intensity on T2-weighted magnetic resonance (MR) images. A wide spectrum of imaging appearances is seen, however, and pheochromocytomas may mimic other adrenal lesions, both benign and malignant. They may be dark on T2-weighted MR images, in contrast to their more classic bright T2-weighted appearance. Other atypical features include fatty, hemorrhagic, cystic, and calcific changes. Pheochromocytomas may contain sufficient fat to be mistaken for an adenoma at computed tomography (CT) or MR imaging. They may also demonstrate rapid contrast material washout and be mistaken for an adenoma owing to their deenhancement profile; however, their washout pattern can be inconsistent. The appearance of pheochromocytomas at radionuclide imaging is also unpredictable. These characteristics at CT, MR imaging, and scintigraphy pose diagnostic challenges, since they allow pheochromocytomas to mimic many other adrenal masses. Pheochromocytoma is an important, often clinically occult neoplasm with devastating consequences if overlooked. Radiologists must be aware of the various forms that pheochromocytomas can assume at imaging.

Adrenal Gland Neoplasms↗
PubMed2004

Recurrent abdominal and pelvic abscesses: incidence, results of repeated percutaneous drainage, and underlying causes in 956 drainages.

OBJECTIVE: We undertook this study to determine the incidence and results of repeated (secondary) percutaneous abscess drainage performed on recurrent abscesses after successful initial (primary) percutaneous abscess drainage. MATERIALS AND METHODS: Imaging studies from patients who underwent multiple drainages were reviewed to define a cohort of patients who underwent secondary percutaneous abscess drainage after successful initial percutaneous abscess drainage of the same abscess. Medical records of these patients were then reviewed to assess the results of secondary percutaneous abscess drainage. RESULTS: Forty-five abscesses in 43 patients required secondary percutaneous abscess drainage. Twenty-four of the 43 patients avoided surgery. Secondary percutaneous abscess drainage was successful in evacuating the abscess cavity in 39 (91%) of 43 patients. Duration of drainage and time until recurrence were not significant predictors for avoiding surgery. Mean duration of secondary percutaneous abscess drainage was significantly longer than mean duration of primary percutaneous abscess drainage, but duration of secondary percutaneous abscess drainage (25 vs 14 days, respectively; p = 0.007) did not differ significantly between patients who ultimately required surgery and those who did not (17 vs 11 days, respectively; p = 0.10). Time to recurrence ranged from 2 days to 1 year (mean, 51 days). CONCLUSION: After successful primary percutaneous abscess drainage, secondary percutaneous abscess drainage of recurrent abscesses succeeded in evacuating the abscess cavity in most patients, and surgery was avoided by slightly more than half. Patients with postoperative abscesses were significantly more likely to avoid surgery (p = 0.008), whereas patients with pancreatic abscesses were significantly more likely to require it (p = 0.03).

Abdominal Abscess↗
PubMed2004

Enteric feeding with gastric decompression: management with separate gastric accesses.

OBJECTIVE: Our purpose is to describe our experience with combined enteral feeding and gastric decompression or drainage in debilitated patients with persistent gastroesophageal reflux using two separate catheters. CONCLUSION: The placement of two percutaneous catheters through separate skin sites is a feasible and successful approach to providing enteral feeding and gastric decompression or drainage in debilitated patients with persistent gastroesophageal reflux and aspiration pneumonia.

Adolescent↗
PubMed2004

Portable abdominal CT: analysis of quality and clinical impact in more than 100 consecutive cases.

OBJECTIVE: Our aim was to determine portable abdominal CT image quality and clinical content in a consecutive series of scans obtained in ICUs at a single center. MATERIALS AND METHODS: All helical portable abdominal CT scans obtained between June 1999 and December 2000 were reviewed by two observers. Image quality was assessed for feature detection and overall quality compared with the patients' contemporaneous stationary CT scans. Hospital records were used to determine patient demographics, scanning indications, and clinical impact and to verify portable CT findings when possible. RESULTS: One hundred twenty-two helical portable CT scans (47 contrast-enhanced) and 41 contemporaneous stationary CT scans in 107 patients were included. IV contrast material improved portable CT scan quality, but quality scores for portable CT scans were consistently lower than those for stationary CT scans, both with and without contrast material. Thirty-three conditions suspected before scanning were supported by findings on portable CT scans, which detected evidence of infection in 18 and hemorrhage in 16 cases and motivated seven laparotomies and six percutaneous drainage procedures. Thirty-three portable CT scans (27%) contributed to a change in patient treatment. Results of surgery or autopsy confirmed portable CT findings in 12 of 17 cases. CONCLUSION: Although image quality is inferior to conventional stationary CT, portable abdominal CT provides important diagnostic information without requiring patient transport outside the ICU. Radiologists should avoid overconfident interpretation of portable CT scans.

Adolescent↗
PubMed2004

CT appearance of acute appendagitis.

OBJECTIVE: Our aim was to describe the spectrum of CT findings in patients with acute epiploic appendagitis and also to evaluate the changes seen with this condition. MATERIALS AND METHODS: Fifty patients diagnosed with acute epiploic appendagitis seen on contrast-enhanced CT were included in this study. The CT scans of the epiploic appendagitis were evaluated for the presence of colon wall thickening, a focal fatty center, inflammatory changes, location in relationship to the colon, size, and presence or absence of central high density within the fat. In 10 patients, the initial findings were compared with findings of follow-up CT performed between 3 days-21 months after the first CT. RESULTS: The most common part of colon involved by acute epiploic appendagitis was the sigmoid colon (31/50), and the most common position was anterior to the colonic lumen (41/50). All 50 patients with acute epiploic appendagitis had a central fatty core surrounded by inflammation. Colon wall thickening was present in only two, and a central high-density focus was noted only in 27 of 50 patients. In 86% (43/50) of patients, the fatty central core was between 1.5 and 3.5 cm in length. The changes seen on follow-up CT varied, including increased density with a decrease in the size of the fatty central core, no change, complete resolution of findings, and minimal residual density. CONCLUSION: On CT, acute epiploic appendagitis has a predictable appearance in terms of location, size, and density. The most common finding on CT is a fat-density oval lesion with surrounding inflammation on the anterior aspect of the sigmoid colon. The changes on CT are not predictable in the 2-week to 6-month window.

Abdomen, Acute↗