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Peter R Mueller

Publications and source records attributed to Peter R Mueller.

At least 55 records · Page 3Linked to original sources
PubMed2004

Radiofrequency ablation: an alternative treatment method of renal cell carcinoma.

Renal Cell Carcinoma (RCC) is a common renal parenchymal malignancy. Although complete or partial nephrectomy is still the gold standard of management, a lot of minimally invasive techniques are currently emerging into the field of treatment. Recently, image-guided radiofrequency (RF) ablation has received increasing attention and been proposed as an alternation to more invasive procedures such as partial or radical nephrectomy. For the RCC patients who are not amenable to surgery or have a single kidney, RF ablation is another feasible option of management. We present a 71-year-old patient who had right nephrectomy for RCC 10 years prior to admission, and hypertension and arrhythmia under regular treatment. He was noted to have two masses in the left kidney and right adrenal gland, respectively, on follow-up computed tomography images. Percutaneous biopsies of the left renal and right adrenal masses were proven to be renal cell carcinoma. After a right adrenalectomy was performed, this patient underwent two treatment sessions of percutaneous RF ablation to avoid a nephrectomy which would lead her on dialysis. Successful treatment was impressed after 1 year of follow-up. We report this case to emphasize the potential role of percutaneous RF ablation on the treatment of RCC.

Aged↗
PubMed2003

Transgluteal approach for percutaneous drainage of deep pelvic abscesses: 154 cases.

PURPOSE: To assess the effectiveness of a computed tomographic (CT) image-guided transgluteal approach for percutaneous drainage of deep pelvic abscesses as an alternative to surgical drainage. MATERIALS AND METHODS: The medical records of 140 patients who underwent percutaneous CT-guided transgluteal drainage of 154 deep pelvic abscesses were reviewed to determine the origins, location, and size of the abscesses; volume of initial aspirate; organisms identified in fluid culture; duration of catheter drainage; incidence of catheter-related pain and procedure-related complications; and short- and long-term outcomes. The resultant data were analyzed with a Fisher exact test for difference in the incidence of postprocedural catheter-site pain between transpiriformis and infrapiriformis approaches. RESULTS: The origins of the pelvic abscesses included postoperative fluid collection (n = 115), perforating appendicitis (n = 6), diverticulitis (n = 16), tubo-ovarian inflammation (n = 5), Crohn disease (n = 10), and internal bowel fistula due to irradiation (n = 2). The abscesses were 4-12 cm in diameter. The volume of the aspirate was 5-310 mL. Laboratory cultures of the aspirate grew mixed flora, but the organism most frequently isolated was Escherichia coli. Catheters were removed after a mean of 8 days. In 134 (96%) of 140 patients, there was complete resolution of the abscess following transgluteal drainage, without subsequent surgery. In six of 140 (4%) patients, incomplete resolution necessitated subsequent surgery for postoperative fluid collection (n = 3), diverticulitis (n = 2), or perforating appendicitis (n = 1). Complications of transgluteal drainage were rare and included hemorrhage in three (2%) of the 140 patients. There was no procedure-related mortality. A transpiriformis approach was significantly more likely to be associated with postprocedural pain (P <.001) than was an infrapiriformis approach. CONCLUSION: Percutaneous CT-guided transgluteal drainage is a safe and effective alternative to surgery for deep pelvic abscesses. Major complications are rare.

Abscess↗
PubMed2003

Interventional approach to pancreatic fluid collections.

Interventional radiologic catheter drainage may be an effective therapeutic approach to fluid collections complicating acute pancreatitis. Pancreatic pseudocysts and abscess are the most common conditions requiring radiologic intervention. Imaging guidance is best performed under CT control allowing precise definition of access route, catheter placement, and response. Access routes are chosen to avoid traversing vital intervening structures, especially the pleural space, colon, and small bowel. Optimal results are achieved with the use of large-bore multihole catheters, prolonged duration of drainage, and careful collaboration with the surgical team.

Abscess↗
PubMed2003

Renal cell carcinoma: clinical experience and technical success with radio-frequency ablation of 42 tumors.

PURPOSE: To evaluate clinical experience with percutaneous image-guided radio-frequency (RF) ablation of renal cell carcinoma (RCC) and to assess factors that may influence technical success. MATERIALS AND METHODS: Thirty-four patients who underwent RF ablation of 42 RCC tumors during a 3.5-year period were evaluated. Overlapping ablations were performed on the basis of tumor size and geometry. Technical success was defined as elimination of areas that enhanced at imaging within the entire tumor. With the exception of those patients with renal insufficiency, who were followed up with unenhanced and gadolinium-enhanced magnetic resonance imaging, patients were followed up with unenhanced and contrast material-enhanced computed tomography. Univariate analysis of the results was performed with the Fisher exact test to assess the effect of tumor size and location on technical success. P 3.0 cm) tumors, presence of a tumor component in the renal sinus was a significant negative predictor of technical success (P =.004); only five of these 11 tumors were completely treated, compared with 11 of 11 tumors without a renal sinus component. A similar analysis was not possible for small tumors because no small tumors involved the renal sinus. Four complications occurred in a total of 54 ablation sessions: one minor hemorrhage, two major hemorrhages, and one ureteral stricture. CONCLUSION: RF ablation of RCC can be successful in exophytic RCC tumors up to 5.0 cm in size. Tumors larger than 3.0 cm with a component in the renal sinus are more difficult to treat but can be ablated successfully.

Adult↗
PubMed2003

Incidence of malignancy in complex cystic renal masses (Bosniak category III): should imaging-guided biopsy precede surgery?

OBJECTIVE: Complex indeterminate renal cystic masses (Bosniak type III) can have benign and malignant causes and have been traditionally considered surgical lesions. We sought to determine the incidence of malignancy and to assess a possible role for imaging-guided biopsy for this category of renal masses. MATERIALS AND METHODS: Three hundred ninety-seven renal biopsies were performed at our institution between 1991 and 2000. Between January 1997 and August 2000, 28 Bosniak category III lesions, based on established CT imaging criteria on helical CT scans, were identified for analysis. The incidence of malignancy, based on surgical pathology or imaging follow-up and percentage of lesions proceeding to surgery, among these 28 lesions, was determined. The surgical results were correlated with the biopsy findings. RESULTS: Of the 28 biopsied category III lesions, 17 (60.7%) were malignant (16 renal cell carcinomas and one lymphoma), and 11 (39.3%) were benign (six hemorrhagic cysts, three inflammatory cysts, one metanephric adenoma, and one cystic oncocytoma). Seventeen of the 28 lesions (16 renal cell carcinomas and one inflammatory cyst) had surgical resection after the biopsy. All resected lesions had pathologic diagnoses identical to the percutaneous imaging-guided biopsy results. The remaining 11 patients who had undergone nonsurgical biopsies had radiologic follow-up for a minimum of 1 year, with benign lesions showing no interval change. CONCLUSION: Renal biopsy and radiologic follow-up were useful in identifying nonmalignant lesions in complex cystic renal masses and avoided unnecessary surgery in 39% of patients.

Adult↗
PubMed2003

Bowel wall fat halo sign in patients without intestinal disease.

OBJECTIVE: Stratification with a fat layer in the intestinal wall is thought to be a reliable marker for inflammatory bowel disease. We evaluated the presence and frequency of the bowel wall fat halo sign in patients undergoing abdominal CT for clinical indications unrelated to the gastrointestinal tract. MATERIALS AND METHODS: We performed a retrospective review of 100 consecutive abdominal and pelvic CT examinations in 61 men and 39 women (mean age, 56 years) with clinical suspicion of renal stone disease. Two radiologists experienced in abdominal imaging performed qualitative and quantifiable assessment of the images. Five segments of the colon (ascending colon, transverse colon, descending colon, sigmoid colon, and rectum) and the terminal ileum (for approximately 1 ft [30 cm]) were evaluated for the presence of the fat halo sign. If the fat halo sign was present, fat density and total wall-thickness assessments were made. Presence or absence of clinical and radiologic signs of inflammatory bowel disease was determined. The Student's t test was used to evaluate the statistical significance, correlating body weight and presence of the halo sign. RESULTS: The fat halo sign was seen in 21 (21%) of 100 patients. Of the 21 patients with the fat halo sign, six (29%) had renal stone disease and 15 (71%) had no stone disease. The density value of the halo sign ranged from -18 to -64 H (mean, -41 H). The distribution of the fat halo sign was as follows: the terminal ileum, 4%; the ascending colon, 28%; the transverse colon, 34%; the descending colon, 36%; the sigmoid colon, 14%; and rectum, 10%. No patient with this sign had any remote, recent, or subsequently recorded history of inflammatory bowel disease. A statistically significant relationship (p < 0.001) was seen between the presence of the fat halo sign and body weight distribution, with 16 of 21 patients weighing over 200 lb (90 kg). CONCLUSION: In the absence of clinical or radiologic evidence of inflammatory bowel disease, the presence of the fat halo sign may represent a normal finding that is possibly related to obesity.

Adipose Tissue↗
PubMed2003

Low-density pheochromocytoma on CT: a mimicker of adrenal adenoma.

OBJECTIVE: Attenuation values on CT of less than 10 H are considered characteristic of adrenal adenomas. Adrenal pheochromocytomas can infrequently contain fat that could result in low attenuation on CT. The purpose of our study was to determine if pheochromocytomas could be confused with adenomas by virtue of their attenuation values on unenhanced CT. MATERIALS AND METHODS: CT attenuation and size of nine adrenal nodules producing pheochromocytoma syndrome were measured on unenhanced CT in nine patients. For five patients who received IV contrast material, washout profiles were also calculated. RESULTS: Two of the nine patients had adrenal lesions with attenuation values of less than 10 H; one had a pheochromocytoma with an attentuation of 9.0 H, and the other had a medullary hyperplasia with an attenuation of 1.8 H. These two nodules showed evidence of microscopic fat at histologic examination. No macroscopic fat was seen on the CT scans. The remaining seven patients had lesions with attenuation values exceeding 10 H (mean value, 25.6 H; range, 1.8-41 H). Mean diameter of the nine tumors (including the hyperplastic nodule) was 3.2 cm (range, 0.8-6.7 cm; SD, +/- 2.3 cm). The two low-attenuation lesions also mimicked adenomas by displaying more than 60% contrast washout on 10-min-delayed contrast-enhanced scans, unlike the other three pheochromocytomas for which we had washout data. CONCLUSION: On CT, pheochromocytomas may have attenuation values less than 10 H and also may display more than 60% washout of contrast agents on delayed scanning. Adrenal pheochromocytomas should be included with adenomas in the differential diagnosis both for masses with low attenuation on unenhanced CT and for lesions exhibiting a high percentage of contrast washout.

Adenoma↗
PubMed2002

Percutaneous radiofrequency ablation of nodal metastases.

We report our experience with percutaneous image-guided radiofrequency (RF) ablation to treat isolated nodal metastases. Four patients underwent image-guided percutaneous RF ablation of metastatic disease involving retrocrural nodes, retroperitoneal nodes, or pelvic nodes. Coagulation necrosis was achieved in all cases.

Aged↗
PubMed2002

US-guided fine-needle aspiration biopsy of thyroid nodules: adequacy of cytologic material and procedure time with and without immediate cytologic analysis.

PURPOSE: To compare the adequacy of aspirated material and procedure time when performing ultrasonography-guided fine-needle aspiration biopsy of thyroid nodules with and without immediate cytologic analysis of the aspirated sample. MATERIALS AND METHODS: One hundred twenty-one thyroid nodules were sampled for biopsy in 109 patients. In group A, results of 50 biopsies in which immediate cytologic analysis was performed were retrospectively reviewed for cytologic adequacy. In group B, 50 biopsies were performed without immediate cytologic analysis, and the procedure time was recorded. In group C, 21 biopsies were performed with immediate cytologic analysis, and the procedure time was recorded. Cytologic adequacy rates were compared by using the proportional odds model, and procedure times were compared by using linear regression to adjust for differences in the character of the nodules. RESULTS: For groups A and C (immediate cytologic analysis performed), the adequacy categories included the following results: 39 (55%) satisfactory, 15 (21%) limited, and 17 (24%) unsatisfactory. For group B (immediate cytologic analysis not performed), the adequacy categories included the following results: 25 (50%) satisfactory, 15 (30%) limited, and 10 (20%) unsatisfactory (Wald test, P =.815). The average procedure time was 12.5 minutes for group B and 44.4 minutes for group C (P <.001). CONCLUSION: There was no significant difference in cytologic adequacy whether immediate cytologic analysis of aspirated material was performed or not. The procedure time was significantly shorter when immediate cytologic analysis was not performed.

Adult↗
PubMed2002

Percutaneous abscess drainage in Crohn disease: technical success and short- and long-term outcomes during 14 years.

PURPOSE: To determine technical success with percutaneous abscess drainage (PAD) in patients with Crohn disease during 14 years. MATERIALS AND METHODS: Medical records of 32 patients with Crohn disease who underwent PAD from 1985 to 1999 were reviewed. Results of abscess drainage and nature of subsequent surgical procedures were recorded. Factors assessed included postoperative or spontaneous nature of the abscess, documentation of a proved fistula, history of occurrence of prior abscesses, duration of Crohn disease, and use of steroid treatment. Technical success was defined as complete abscess drainage. Short-term success was defined as avoidance of surgery within 60 days of drainage. Long-term success was defined as avoidance of surgery beyond the initial 60-day period. Short-term avoidance of surgery was assessed as a predictor of the need for surgery in the long term. Statistical analysis was performed with the chi(2) test to evaluate predictors of short-term success and to assess short-term success as a predictor of long-term success. RESULTS: The technical success rate was 96%. In 16 (50%) of 32 patients, the need for surgery in the short term was avoided, and surgery was more likely to be avoided in patients with postoperative abscesses than in those with spontaneous abscesses (P =.07). At long-term follow-up, short-term avoidance of surgery did not significantly increase the likelihood of need for surgery in the long term, which occurred in nine of 16 short-term successes versus five of 15 short-term failures (P =.55). Recurrent abscesses occurred in seven (22%) patients, a rate comparable to that with surgical abscess drainage; four (44%) of nine cases of re-drainage were successful. CONCLUSION: PAD has a high technical success rate of 96%. Half of patients may avoid surgery in the short term.

Abdominal Abscess↗
PubMed2002

Cystic lymph node metastases in papillary thyroid carcinoma.

OBJECTIVE: The aim of this study was to illustrate and discuss the sonographic spectrum of surgically proven cystic nodal metastases from papillary thyroid carcinoma. By correlative evaluation of the sonographic imaging findings to gross pathology and histology, our purpose was to provide useful hints to differentiate cystic lymph node metastases from other benign cystic neck lesions such as branchial cysts. MATERIALS AND METHODS: Sonographic examinations of 74 patients (47 women, 27 men; mean age, 49 years) with 97 histologically confirmed cystic lymph nodes metastases from papillary thyroid carcinoma were included in the study. The anatomic relationship of the nodes relative to the primary tumor was recorded, and all cystic nodes were qualitatively categorized as either simple (purely cystic) or complex (thickened outer wall, internal nodules, internal septations, and calcifications). All imaging findings were compared with gross pathologic specimens. RESULTS: Most of the cystic metastases were ipsilateral to the primary tumor (87.8%) and located in the mid or lower jugular chain (73.2%). In 14.9% of all patients, cystic lymph node metastases were the initial manifestation of disease. Only 6.2% of all lymph node metastases were purely cystic (all of these occurred in patients less than 35 years old). Of the 91 complex metastases, a thickened outer wall was present in 35.2% of patients, internal nodules in 42.9%, and internal septations in 57.1%. No calcifications were seen in the 91 complex metastases, and two or more findings were seen in 23.1%. All sonographic findings were verified by surgery. CONCLUSION: In most of the patients, cystic lymph node metastases are characterized sonographically by the presence of a thickened outer wall, internal echoes, internal nodularity, and septations. However, in younger patients, the lymph nodes might appear purely cystic, thereby mimicking branchial cysts and thus requiring biopsy for final diagnosis and therapy planning.

Adult↗