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P R Mueller

Publications and source records attributed to P R Mueller.

At least 19 recordsLinked to original sources
PubMed2001

CT colonography with teleradiology: effect of lossy wavelet compression on polyp detection--initial observations.

PURPOSE: To assess the consequences of lossy compression on the diagnostic accuracy of CT colonography for detecting colonic polyps. MATERIALS AND METHODS: Helical CT images of cleansed colonic segments were evaluated. Source images were compressed to 1:1, 10:1, and 20:1 ratios with lossy wavelet compression. Two independent readers blinded to corresponding colonoscopic results analyzed 144 randomly ordered colonic segments in multiplanar and volume-rendered endoscopic views. Sensitivity, specificity, and receiver operating characteristic curves were generated for each compression ratio on the basis of expressed confidence in lesion presence. Similar analyses were performed to assess distention and bowel preparation adequacy and evaluation time required. RESULTS: Results based on video colonoscopy-confirmed lesions revealed 100% (four of four) sensitivity for lesions larger than 10 mm for compression ratios 1:1, 10:1, and 20:1 for both readers; sensitivities for all lesions smaller than 10 mm were 50%-78%, 38%-67%, and 38%-67% for respective ratios for both readers. Differences in diagnostic performance for each reader across ratios were not significant (P =.30-.99, McNemar test). The time required to evaluate and assess bowel preparation and distention adequacy did not change significantly across ratios. CONCLUSION: On the basis of the patient sample, lossy compression of transverse source images to at least a 20:1 ratio did not adversely affect diagnostic performance or evaluation time for CT colonography.

Aged↗
PubMed2001

Prevalence of incidental Bochdalek's hernia in a large adult population.

OBJECTIVE: The purpose of this study was to determine the prevalence and characteristics of adult Bochdalek's hernia in a large patient population. MATERIALS AND METHODS: We retrospectively reviewed all abdominal CT scans obtained at our hospital in 1998. Patients in our study were identified through a keyword search of our database for "Bochdalek," "hernia," and "diaphragm." The individual patient studies identified were reviewed in a soft-copy format. We noted the location and side of the body on which the diaphragmatic hernia arose and the contents of the sac. We also performed a chart review for each patient included in the study, noting the patient's sex, age, and symptoms. RESULTS: Incidental Bochdalek's hernia was diagnosed in 22 patients (17 women, five men), which represents an incidence of 0.17% based on 13,138 abdominal CT reports we reviewed. The mean age of the patients was 66.6 years. None of the patients were symptomatic. Sixty-eight percent of the hernias were on the right side of the body, 18% were on the left side, and 14% were bilateral. Seventy-three percent contained only fat or omentum, whereas 27% had solid or enteric organ involvement including the spleen, small intestine, or large intestine. CONCLUSION: Bochdalek's hernia is not rare, and the incidence of Bochdalek's hernias that contain enteric tract is higher than previously reported. This incidence likely represents a conservative estimate because some Bochdalek's hernias may have been overlooked or unreported.

Aged↗
PubMed2001

Tunneled peritoneal catheter placement under sonographic and fluoroscopic guidance in the palliative treatment of malignant ascites.

OBJECTIVE: We present a treatment for recurrent, symptomatic ascites in patients with malignant disease. This report summarizes our experience with percutaneous tunneled peritoneal catheters in 24 patients. SUBJECTS AND METHODS: Of the 40 consecutive patients who presented with at least four therapeutic paracenteses in a 4-week period, 24 patients underwent the percutaneous tunneled procedure. All had malignant ascites. RESULTS: All 24 patients had successful insertion of a permanent tunneled peritoneal drainage catheter. Eighteen were outpatients and six were inpatients. All patients were relieved of their clinical symptoms, including abdominal distention and dyspnea, and were relieved of lower extremity discomfort. The mean life span after catheter placement was 7.2 weeks. Twenty (83%) of the 24 patients were treated at home with their catheters in place. Three patients experienced minor complications from bacterial peritonitis, which responded to antibiotics. One patient had to have his catheter removed. CONCLUSION: Percutaneous placement of specialized tunneled catheters appears to be a viable and safe technique in patients who have symptomatic ascites that require frequent therapeutic paracentesis for relief of symptoms.

Adult↗
PubMed2000

Treatment of intrahepatic malignancy with radiofrequency ablation: radiologic-pathologic correlation.

BACKGROUND: Radiofrequency (RF)-induced tissue coagulation represents a new approach for the thermal destruction of tumors within the liver. The purpose of the current study was to 1) assess technique safety; 2) determine the extent and evolution of induced cellular damage; and 3) correlate the observed pathologic effects with radiologic studies. METHODS: Twenty-three tumors measuring </= 8 cm (19 colorectal metastases and 4 hepatomas) in 22 patients were treated with RF (range, 500-1550 milliamperes) using internally cooled electrodes. All treated tumors were resected to allow pathologic analysis. Eleven tumors were treated intraoperatively under ultrasonographic guidance and excised immediately. Twelve tumors were treated percutaneously using ultrasound or computed tomography (CT) guidance and subsequently were excised 3-7 days after ablation. Contrast-enhanced CT (n = 12) and magnetic resonance imaging (MRI) (n = 2) were performed after ablation of all percutaneously treated patients. RESULTS: Tumors treated intraoperatively did not demonstrate definitive coagulative necrosis. However, pathologic abnormalities suggestive of tissue injury were observed with hematoxylin and eosin staining, and absent cytosolic and mitochondrial enzyme activity suggested irreversible cellular damage. In contrast, specimens removed > 3 days after ablation showed definite, contiguous coagulative necrosis without intervening areas of viable tumor. CT and MRI scans demonstrated circumscribed hypodense, nonenhancing regions surrounding the electrode tract as early as 15 minutes after ablation. These corresponded within 2 mm to measurements of coagulation at pathology. CONCLUSIONS: RF ablation is a minimally invasive and safe approach to the treatment of tumors in the liver. Tumors treated with RF energy do not immediately demonstrate coagulative necrosis, but do show evidence of irreversible cellular damage. The extent of tumor necrosis correlates closely with findings at contrast-enhanced imaging.

Aged↗
PubMed2000

Interventional radiologic procedures: patient anxiety, perception of pain, understanding of procedure, and satisfaction with medication--a prospective study.

PURPOSE: To prospectively assess patient anxiety, understanding of the procedure being performed, perception of pain level, and satisfaction with medication given for a variety of diagnostic and therapeutic vascular and visceral (nonvascular) interventional procedures. MATERIALS AND METHODS: The authors interviewed 204 patients before and after they underwent an interventional radiologic procedure. Patients responded to a series of questions by using a visual analog scale. Patients were grouped according to (a) their level of experience with the procedure and (b) the type of procedure performed (diagnostic or therapeutic visceral procedure or diagnostic or therapeutic vascular procedure). RESULTS: Patients who had previous experience with a procedure, whether visceral or vascular, were less anxious, had more understanding, and anticipated less pain than did those who did not have experience with a procedure. Patients who had only local anesthesia for visceral biopsy experienced greater pain than did those who had both local and intravenous anesthesia. Satisfaction scores, however, were similar throughout all groups. CONCLUSION: Patients have a moderate amount of anxiety about interventional procedures and anticipate some discomfort. Most patients have a high level of satisfaction despite the amount of pain they experience during the procedure. Patients experienced with a procedure tend to have a greater understanding of the procedure and less anxiety.

Adult↗
PubMed2000

Characterization of indeterminate (lipid-poor) adrenal masses: use of washout characteristics at contrast-enhanced CT.

PURPOSE: To determine whether computed tomographic (CT) scans and attenuation measurements on contrast material-enhanced and nonenhanced CT scans could be used to characterize adrenal masses, in particular, to characterize these lesions by using adrenal washout characteristics at contrast-enhanced CT. MATERIALS AND METHODS: Eighty-six patients (49 men, 37 women; age range, 29-86 years; mean age, 72 years) with 101 adrenal lesions depicted at contrast-enhanced CT underwent delayed (mean, 9 minutes) enhanced scanning. Seventy-eight patients also underwent nonenhanced CT. Mean diameter of the benign lesions was 2.1 cm (range, 1.0-4.2 cm); mean diameter of the malignant lesions was 2.3 cm (range, 1.0-4.1 cm). Region-of-interest measurements were obtained at nonenhanced, dynamic enhanced, and delayed enhanced CT and were used to calculate a relative percentage washout as follows: 1 - (Hounsfield unit measurement on delayed image / Hounsfield unit measurement on dynamic image) x 100%. RESULTS: Ninety-nine of 101 lesions were correctly characterized as benign or malignant with a relative percentage washout threshold of 50% on delayed scans; benign lesions demonstrated more than 50% washout; and malignant lesions, less than 50% washout. Two benign lesions demonstrating less than 50% washout were characterized as benign by using conventional CT. CONCLUSION: Calculation of relative percentage washout on dynamic and delayed enhanced CT scans may lead to a highly specific test for adrenal lesion characterization, reduce the need for, and possibly obviate, follow-up imaging or biopsy.

Adenoma↗
PubMed2000

Radio-frequency ablation of renal cell carcinoma: early clinical experience.

PURPOSE: To report the authors' early experience with radio-frequency (RF) ablation of renal cell carcinoma. MATERIALS AND METHODS: Twenty-four percutaneous RF ablation treatments for nine tumors were performed in eight patients with renal cell carcinoma. Indications included coexistent morbidity, previous surgery, or solitary kidney in patients with a life expectancy shorter than 10 years. Smaller (</=3-cm) peripheral lesions (n = 3) were treated with single electrodes. All but one of the larger (>3 cm) and/or central lesions (n = 6) were treated with cluster or multiple electrodes. Patients returned for a second treatment when follow-up imaging depicted tumor enhancement. Follow-up imaging was performed at 1 and 3 months and then at 6-month intervals, with a mean follow-up of 10.3 months. Seven patients were alive at least 6 months after their initial treatment. RESULTS: All five exophytic tumors were free of enhancement. One of three central tumors was free of enhancement. One tumor had both central and exophytic components and was free of enhancement. Three tumors were 3 cm or smaller and free of enhancement. Of the six tumors larger than 3 cm, four were free of enhancement. CONCLUSION: Percutaneous RF ablation is a promising treatment for select patients with renal cell carcinoma. The ultimate role of this modality will continue to evolve and warrants further study.

Aged↗
PubMed2000

Prevalence and significance of gallbladder abnormalities seen on sonography in intensive care unit patients.

OBJECTIVE: We evaluated sonographic abnormalities of the gallbladder other than acalculous cholecystitis across a broad range of intensive care unit (ICU) patients. SUBJECTS AND METHODS: Fifty-five consecutive patients (age range, 18-94 years old; mean age, 56 years; 33 men, 22 women), who were admitted to the ICU with a variety of diagnoses, underwent sonography of the gallbladder twice a week. Patients with gallbladder calculi were excluded from the study. The gallbladder was examined for the recognized sonographic features of acalculous cholecystitis: gallbladder wall thickening, gallbladder distention, intramural gallbladder lucencies (striated gallbladder wall), pericholecystic fluid, gallbladder sludge, and Murphy's sign. These findings were correlated with clinical and laboratory parameters that are associated with acalculous cholecystitis: fever, WBC, liver function tests, levels of serum bilirubin, mechanical ventilation status, and administration of parenteral nutrition, narcotic analgesics, antibiotics, and pressor agents. RESULTS: Eleven of the 55 patients were found to have gallbladder calculi and were excluded from the study. Thirty-seven (84%) of the remaining 44 patients had at least one sonographic abnormality while in the ICU. Twenty-five (57%) of the 44 patients had as many as three abnormalities found on sonography, and six (14%) of 44 patients had four or five sonographic findings of gallbladder abnormalities while in the ICU. No statistically significant correlation was found among any of these sonographic abnormalities and the clinical and laboratory parameters. CONCLUSION: Gallbladder abnormalities are frequently seen on sonography in ICU patients, even if these patients are not suspected of having acalculous cholecystitis; therefore, sonography appears to be of limited value in diagnosing acalculous cholecystitis in ICU patients.

Adolescent↗
PubMed2000

Helical CT protocols for the abdomen and pelvis: a survey.

OBJECTIVE: We surveyed members of the Society of Computed Body Tomography/Magnetic Resonance to evaluate current techniques used for helical CT in the abdomen and pelvis. MATERIALS AND METHODS: The survey was distributed to 70 members (36 institutions) of the Society of Computed Body Tomography/Magnetic Resonance. The survey included general questions related to abdominal and pelvic helical CT and also asked the members to write a protocol for 12 hypothetical requisitions. RESULTS: Thirty-two members (46%) responded, representing 28 institutions (78%). The number of protocols for helical CT of the abdomen and pelvis at each institution ranges from 2 to 35 (median, 11). IV contrast material is administered for 90% (median) of abdominal and pelvic CT examinations. Nonionic contrast material is used for 68% (median) of these examinations. IV contrast material is used by 100% of institutions for tumor staging protocols except for one institution that does not use IV contrast material for lymphoma staging. Fifty percent of the institutions obtain two- or three-phases of liver images for breast cancer staging. For all protocols, the average collimation and reconstruction interval is 7 mm except for renal (5 mm) and adrenal (4 mm) protocols. Rectal contrast material is administered most commonly for colon cancer staging (39% of institutions). CONCLUSION: There is a wide range in the number of protocols used for helical CT in the abdomen and pelvis among the responding institutions. Most protocols include use of nonionic IV contrast material injected at a rate of 3 ml/sec and a collimation of 7 mm.

Clinical Protocols↗
PubMed2000

Efficacy of percutaneous abscess drainage in patients with vancomycin-resistant enterococci.

OBJECTIVE: We reviewed a 4-year experience draining fluid collections infected with vancomycin-resistant enterococci to determine the outcome of percutaneous intervention in patients with this highly resistant and increasingly common organism. MATERIALS AND METHODS: Charts of patients from whom vancomycin-resistant enterococci had been isolated during percutaneous drainage were reviewed to determine patient response to drainage, catheter management, and outcome of treatment. RESULTS: Twenty-one patients underwent percutaneous drainage of 28 fluid collections from which vancomycin-resistant enterococci were isolated, including 16 intraabdominal abscesses, seven biliary or urinary obstructions, and five empyemas. The drainage of 27 (96%) of 28 collections were technically successful. In seven patients, drainage provided the first isolation of vancomycin-resistant enterococci from the patient. Five patients also had blood cultures with positive findings for vancomycin-resistant enterococci, and 14 collections were coinfected with other bacteria or with fungi. Twenty collections (71%) or obstructions were successfully treated with percutaneous drainage. Drainage was unsuccessful in treating eight collections in seven patients. CONCLUSION: Despite high-level antibiotic resistance, fluid collections infected with vancomycin-resistant enterococci can be successfully drained percutaneously, resulting in a favorable likelihood of recovery for patients.

Abscess↗
PubMed2000

CT-Guided transgluteal drainage of deep pelvic abscesses in children: selective use as an alternative to transrectal drainage.

OBJECTIVE: The transgluteal approach to abscess drainage through the greater sciatic foramen has been described in adults, but this route has not been as extensively studied in children. We performed CT-guided transgluteal percutaneous abscess drainage in seven children and assessed the results of drainage and catheter tolerance. CONCLUSION: Transgluteal catheters are well tolerated by children, and the transgluteal route is an effective approach to selected pelvic abscesses in children.

Abdominal Abscess↗
PubMed2000

Dose reduction in gastrointestinal and genitourinary fluoroscopy: use of grid-controlled pulsed fluoroscopy.

OBJECTIVE: We evaluated the diagnostic accuracy of a grid-controlled fluoroscopy unit compared with a conventional continuous fluoroscopy unit for a variety of abdominal and pelvic fluoroscopic examinations. SUBJECTS AND METHODS: Seventy patients (29 men and 41 women; age range, 24-78 years) were enrolled in one of seven abdominal and pelvic fluoroscopic examinations, including upper gastrointestinal series (n = 20), barium enema (n = 10), voiding cystourethrogram (n = 10), percutaneous abdominal catheter tube injection (n = 10), hysterosalpingogram (n = 10), and percutaneous needle insertion and catheter placement (nephrostomy, percutaneous biliary drainage) (n = 10). Each patient underwent at least 10 sec of continuous fluoroscopy that was randomly and blindly compared with 10-sec periods of pulsed fluoroscopy at 15, 7.5, and 3.75 frames per second. A radiologist outside the examination room, unaware of the frame rate per second, evaluated the procedure in real time on a television monitor. The radiologist assessed image quality and diagnostic acceptability using a scoring system. Statistical analysis was performed using the paired Student's t test. RESULTS: For all procedures at all frame rates, we found no statistically significant superiority of one frame rate over another. For most procedures, the slower frame rates were considered equivalent to continuous fluoroscopy when the images were assessed for image quality and diagnostic confidence. CONCLUSION: Our findings suggest that most abdominal and pelvic fluoroscopic procedures can be performed at substantially lower frame rates than those used for continuous fluoroscopy; adopting this procedure may lead to substantial dose savings for the patient and the fluoroscopy operator.

Adult↗
PubMed1999

Imaging guided biopsy of renal masses: indications, accuracy and impact on clinical management.

PURPOSE: We evaluated the indications, accuracy and impact of image guided biopsy of focal renal masses. MATERIALS AND METHODS: We retrospectively reviewed 79 image guided renal biopsies in 73 patients. Indications, imaging, and histological and clinical features were analyzed. We assumed that nephrectomy, partial nephrectomy or surgical biopsy of suspicious masses would be done when no percutaneous biopsy had been performed. A change in management was defined as surgical to nonsurgical. RESULTS: Clinical management was altered due to results in 32 of the 79 biopsies (41%) in cases managed nonoperatively, including positive and negative biopsies in those followed clinically and with imaging. Of 79 biopsies 49 (62%) were diagnosed positive for malignancy, including 15 (31%) that were not and 34 (69%) that were renal cell carcinoma. The histological diagnosis was negative on 25 biopsies (32%) and positive or negative on 74 (94%). All 5 of the 79 false-negative biopsies (6%) were due to insufficient tissue and involved highly suspicious imaging findings that required further evaluation, such as repeat biopsy or surgery. Renal cell carcinoma was identified in 4 of the 5 cases. In 12 of the 24 patients (50%) with a pre-biopsy history of nonrenal cancer biopsies were diagnostic of nonrenal cancer. No patient had major complications and in 4 small hematomas were treated with observation only. CONCLUSIONS: Image guided renal mass biopsy is safe, reliable and accurate, and it changes clinical management in many cases by avoiding nephrectomy or other surgical options. Radiologists should promote imaging guided biopsy as a potentially useful option for managing suspicious or indeterminate renal masses.

Biopsy, Needle↗
PubMed1999

Pancreatic-phase versus portal vein-phase helical CT of the pancreas: optimal temporal window for evaluation of pancreatic adenocarcinoma.

OBJECTIVE: Our objective was to use helical CT to compare the enhancement attenuation values of pancreatic adenocarcinoma, adjacent normal pancreas, and critical vascular structures during the pancreatic phase and portal vein phase. SUBJECTS AND METHODS: Forty-one patients with pathologically proven pancreatic adenocarcinoma underwent dual-phase thin-section dynamic helical CT using a pancreatic-phase and portal vein-phase protocol. The scan delay after initiation of the contrast bolus was 40 sec for the pancreatic phase and 70 sec for the portal vein phase. Attenuation values after i.v. contrast administration were calculated during both phases of scanning for normal pancreas, pancreatic tumor, celiac axis, superior mesenteric artery, superior mesenteric vein, splenic vein, and portal vein. Quantitative values were assessed using regions of interest. RESULTS: Mean differences of enhancement between tumor and normal pancreas were significantly greater in the pancreatic phase (57 H) than the portal vein phase (35 H) (p = .0001). Enhancement values of all the critical vascular structures were also significantly greater in the pancreatic phase than the portal vein phase (p < .001). CONCLUSION: With dynamic thin-section helical CT, pancreatic-phase scanning provides greater differences in contrast enhancement between normal pancreas and pancreatic tumor and between pancreatic tumors and surrounding critical vascular structures than does portal vein-phase scanning.

Adenocarcinoma↗