John Thomas

Duke University, Durham, North Carolina, United States

Are you John Thomas?

Claim your profile

Publications (20)61.43 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: To develop an algorithm to maximize the diagnostic yield of positron emission tomography (PET)/computed tomography (CT) by using defined attenuation and standardized uptake value (SUV) criteria. An IRB-approved, HIPAA-compliant retrospective review with waiver of informed consent of data in 1388 consecutive patients who underwent PET/CT for known or suspected lung cancer was completed, and 187 adrenal nodules were identified in 147 patients. Nodules were defined histologically or by size change (malignant, n = 37) or stability for more than 1 year (benign, n = 58). Nodules not sampled for biopsy and with less than 1 year of follow-up were considered indeterminate (n = 92). Diameter, mean attenuation, SUV(max), and SUV ratio (nodule SUV(max)/liver SUV(avg)) were compared with t test and receiver operating characteristic analyses. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated for diameter > 3 cm, mean attenuation > 10 HU, nodule SUV(max) > 3.1, and SUV ratio > 1.0. These were also calculated for higher SUV(max) and SUV ratio thresholds that were found to exclude all false-positives. Diagnostic accuracy was compared by using the McNemar test (P < .05). Results: In the study group of 147 patients (aged 42-88 years; mean, 65.5 years; 59 women), combined PET/CT with mean attenuation > 10 HU and SUV(max) > 3.1 had 97.3% sensitivity and 86.2% specificity. Combined PET/CT with mean attenuation > 10 HU and SUV ratio > 1.0 had 97.3% sensitivity and 74.1% specificity. The accuracies of these threshold combinations (90.5% and 83.2%, respectively) were significantly different (P = .008). Applying a further cutoff of SUV ratio > 2.5 enabled identification of 22 of 37 metastatic lesions and exclusion of all fluorodeoxyglucose-avid benign nodules. Definitive identification of many metastases can be accomplished by applying an SUV ratio cutoff of greater than 2.5, allowing pragmatic management of adrenal nodules that initially test positive with the combined PET/CT criteria SUV(max) > 3.1 and mean attenuation > 10 HU. Supplemental material: http://radiology.rsnajnls.org/cgi/content/full/250/2/523/DC1.
    Radiology 02/2009; 250(2):523-30. DOI:10.1148/radiol.2502080219 · 6.21 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To provide a snapshot of the demographics of radiologists providing coverage for emergency departments (EDs) and current imaging practices in EDs in the United States. An online survey was created with Views Flash 3 software (Cogix, Monterey, California). Random e-mail addresses from a variety of databases were chosen. A total of 678 surveys were sent over a 9-month period. One hundred ninety-two radiology groups (28%) responded to the survey. Forty-one groups (21%) had designated emergency radiology divisions. Sixty-three groups (33%) were using computed tomographic (CT) coronary angiography in the ED workup of chest-pain. Thirty-five groups (18%) were using "triple-rule-out scans" (ie, a single CT scan to rule out coronary artery disease, pulmonary embolism, and aortic dissection). Multiplanar reconstructions of chest, abdominal, and pelvic CT images were routinely performed by 95 groups (49%). Forty-four percent used reformatted CT images instead of conventional radiographs in the workup of cervical spine trauma, and 68 groups (35%) used reformations in thoracic and lumbar spine trauma. Ninety groups (47%) did not use oral contrast for blunt abdominal trauma CT scanning. Sixty-seven respondents (35%) preferred computed tomography to evaluate for acute appendicitis in the setting of pregnancy. Forty percent of imaging equipment located within the EDs was CT scanners. The majority of the groups still communicated unexpected findings via telephone (49%). New imaging practices for the evaluation of entities such as chest pain, spine trauma, and abdominal pain and trauma are emerging in EDs. As one plans ED development, these trends should be considered.
    Journal of the American College of Radiology: JACR 08/2008; 5(7):811-816e2. DOI:10.1016/j.jacr.2008.02.027 · 2.28 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: PURPOSE To test the hypothesis that adrenal lesion SUVmax may differentiate between adenomas and malignant lesions in a consecutive series of biopsy proven adrenal lesions. METHOD AND MATERIALS From January, 2003 to December, 2005, 33 patients (mean age 58 years, 64% male, 36% female) with adrenal lesions who underwent either PET or PET/CT and adrenal biopsy were identified. Indications for scanning were: non-small cell lung CA (23), small cell lung CA (2), breast CA (2), melanoma (2), ampullary CA (1), cervical CA (1), unknown primary (1), adrenal lesion with no primary (1). In patients who underwent PET only, data from a recent CT scan was utilized. The size, mean density, lesion SUVmax, and lesionSUVmax/liverSUVavg ratio were measured for each lesion and compared to histologic diagnosis. RESULTS Eight adenomas had the following imaging parameters: 2.2 cm (range 1.0-3.3cm), 22.3 HU (range 2.1-43.2HU), SUVmax 5.1 (range 2.0-10.2), lesionSUVmax/liverSUVavg 1.9 (range 0.6-4.1). Twenty-three metastatic lesions had the following imaging parameters: 3.7 cm (range 1.2-8.8cm), 34.9HU (range 14.9-53.5HU), SUVmax 14.1 (range 2.9-25.8), lesionSUVmax/liverSUVavg 5.4 (range 1.2-9.2). One pheochromocytoma measured 2.3cm, 40.9HU, SUVmax 4.5, lesionSUVmax/liverSUVavg 1.7. One angiomyolipoma measured 1.9cm, 21.0HU, SUVmax 7.6, lesionSUVmax/liverSUVavg 4.0. CONCLUSION Though lesion SUVmax for most adenomas is below the SUVavg of liver, some measure well above the SUVavg of liver. However, only two adenomas had values more than 2.5 times that of liver. A lesionSUVmax/liverSUVavg ratio of >2.5 is a specific test for malignancy. CLINICAL RELEVANCE/APPLICATION Occasionally adrenal adenomas can have FDG avidity significantly above that of the liver. However, this value is only rarely greater than 2.5 times the liver.
    Radiological Society of North America 2007 Scientific Assembly and Annual Meeting; 11/2007
  • [Show abstract] [Hide abstract]
    ABSTRACT: PURPOSE To compare two diagnostic PET criteria: 1) lesion SUVmax and 2) SUVratio = (lesion SUVmax)/(liver SUVavg), and to establish a new PET criteria specific for malignancy in the evaluation of adrenal lesions. METHOD AND MATERIALS From a retrospective review of 1388 patients with PET/CT scans (July 2003-August 2005), a total of 187 adrenal lesions were identified in 147 patients (mean age 65.5, female 40.1%, male 59.9%). Malignant lesions (n=37) were defined by biopsy, increase in size, or reduction in size following treatment. Benign lesions (n=99) were defined by biopsy, mean density 10 HU and with less than one year of CT follow up were excluded from further analysis. Sensitivities and specificities of lesion SUVmax >3.1, SUVratio >1.0 and SUVratio >2.5 were calculated. The t-test, Chi-square test (P<.05), and ROCs were used. RESULTS Of 99 benign lesions, 76 (76.0%) had a mean CT density 3.1 and SUVratio >1.0 were present in 19.7% (range 3.2-5.0), and 26.3% (range 1.1-2.1) respectively, indicating that a substantial number of adenomas are FDG avid. Of 60 lesions measuring >10 HU (benign=23 and malignant=37), 44 had a lesion SUVmax >3.1 (sensitivity 97.3% and specificity 65.2%), and 51 had an SUVratio >1.0 (sensitivity 97.3% and specificity 34.8%). Combined PET/CT of 136 benign and malignant lesions for lesion SUVmax >3.1 yielded a 97.3% sensitivity and 91.9% specificity, and for SUVratio >1.0 yielded 97.3% sensitivity and 84.9% specificity. Applying a further cutoff of SUVratio >2.5 identified 22 metastatic lesions with a specificity of 100%. CONCLUSION Lesion SUVmax >3.1 and SUVratio >1.0 performed with equal sensitivity for malignancy. A cutoff of SUVratio >2.5 is 100% specific for malignancy. CLINICAL RELEVANCE/APPLICATION While PET/CT is sensitive, the number of false positive lesions after initial interpretation is problematic. Applying an SUV ratio that is specific for malignancy helps to guide further management.
    Radiological Society of North America 2007 Scientific Assembly and Annual Meeting; 11/2007
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Assess postpartum changes in the levator ani muscle using magnetic resonance imaging and relate these changes to obstetric events and risk factors associated with pelvic floor dysfunction. A board-certified radiologist specializing in abdominal imaging evaluated 146 pelvic magnetic resonance studies from 57 primiparous women 6 weeks and 6 months after first obstetric delivery and 32 nulliparous women. A yes/no determination of muscle body and insertion integrity, muscle thinning, and measurement of muscle thickness in millimeters was made for each of 4 muscle sites: right and left puborectalis and right and left ileococcygeous. Incidence of muscle abnormality and mean muscle thickness was tested in pairs between (1) nulliparous women and 6-week primiparous women; (2) 6 week and 6 month primiparous pairs; and (3) 3 age/race groups using test of 2 proportions and 1-way analysis of variance. Initial review indicated only 3 subjects not of African American or white race, and only 1 African American primiparous woman of age 30 years or older; therefore, statistical analysis was limited to 45 primiparous women and 25 nulliparous women. Incidence of any abnormality at any of the 4 sites was considered abnormal. In those subjects recovering to normal magnetic resonance by 6 months, an average of nearly 60% increase in right puborectalis muscle thickness compared with that seen at 6 weeks indicated the extent of the injury. Subjects with injury to both the puborectalis and ileococcygeous at 6 weeks did not recover to normal at 6 months, whereas those with injury only to the puborectalis tended to have normal magnetic resonance images at 6 months. Nulliparity did not guarantee a normal assessment of levator ani anatomy by our blinded reader, and frequency of injury in this series is somewhat greater than that previously reported for primiparous women. Younger white primiparous women had a better recovery at 6 months than older white women. Subjects experiencing more global injury, in particular to the ileococcygeous, tended not to recover muscle bulk.
    American journal of obstetrics and gynecology 08/2007; 197(1):65.e1-6. DOI:10.1016/j.ajog.2007.02.040 · 3.97 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To prospectively determine quantitatively and qualitatively the timing of maximal enhancement of the normal small-bowel wall by using contrast material-enhanced multi-detector row computed tomography (CT). This HIPAA-compliant study was approved by the institutional review board. After information on radiation risk was given, written informed consent was obtained from 25 participants with no history of small-bowel disease (mean age, 58 years; 19 men) who had undergone single-level dynamic CT. Thirty seconds after the intravenous administration of contrast material, a serial dynamic acquisition, consisting of 10 images obtained 5 seconds apart, was performed. Enhancement measurements were obtained over time from the small-bowel wall and the aorta. Three independent readers qualitatively assessed small-bowel conspicuity. Quantitative and qualitative data were analyzed during the arterial phase, the enteric phase (which represented peak small-bowel mural enhancement), and the venous phase. Statistical analysis included paired Student t test and Wilcoxon signed rank test with Bonferroni correction. A P value less than .05 was used to indicate a significant difference. The mean time to peak enhancement of the small-bowel wall was 49.3 seconds +/- 7.7 (standard deviation) and 13.5 seconds +/- 7.6 after peak aortic enhancement. Enhancement values were highest during the enteric phase (P < .05). Regarding small-bowel conspicuity, images obtained during the enteric phase were most preferred qualitatively; there was a significant difference between the enteric and arterial phases (P < .001) but not between the enteric and venous phases (P = .18). At multi-detector row CT, peak mural enhancement of the normal small bowel occurs on average about 50 seconds after intravenous administration of contrast material or 14 seconds after peak aortic enhancement.
    Radiology 06/2007; 243(2):438-44. DOI:10.1148/radiol.2432060534 · 6.21 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The purposes of this study were to determine the accuracy of abdominal radiography in the detection of acute small-bowel obstruction (SBO), to assess the role of reviewer experience, and to evaluate individual radiographic signs of SBO. A retrospective study was performed in which the subjects were 90 patients with suspected SBO who underwent CT and abdominal radiography within 48 hours of each other. The patients were enrolled from June 1, 2003, to February 2004. Twenty-nine of the patients had proven SBO. Hard-copy radiographs were reviewed by three groups of radiologists: senior staff, junior staff, and second-year radiology residents. Each reviewer evaluated the quality of the radiographs, patient position for acquisition of the radiographs, and whether SBO was present. The reviewers rated their confidence on a five-point scale and recorded the presence or absence of specific radiographic signs of SBO. Chi-square tests were used to compare the three groups. A statistically significant finding was considered p < 0.05. Receiver operating characteristic (ROC) curves were fit with a 10-point confidence scale. The sensitivity for SBO among the six reviewers ranged from 59% to 93%. The senior staff members were significantly more accurate. The mean sensitivity, specificity, and accuracy for all six reviewers were 82%, 83%, and 83%, respectively. Three radiographic signs were highly significant (p < 0.001): two or more air-fluid levels, air-fluid levels wider than 2.5 cm, and air-fluid levels differing more than 5 mm from one another in the same loop of small bowel. ROC analysis showed that senior staff is significantly more accurate than the other groups in the detection of acute SBO. Our results confirmed that abdominal radiographs are accurate in the detection of acute SBO, that more-experienced radiologists are more accurate than less-experienced reviewers in the evaluation of abdominal radiographs, and that three types of air-fluid levels are highly predictive of the presence of SBO.
    American Journal of Roentgenology 03/2007; 188(3):W233-8. DOI:10.2214/AJR.06.0817 · 2.74 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To evaluate whether clips from prior cholecystectomy impair image quality during magnetic resonance cholangiography (MRC) at 3 Tesla (T) compared with 1.5 T, surgical clips were embedded in a gel phantom and positioned at predefined distances from a fluid-filled tube designed to simulate the bile duct. The maximum clip distance was noted where susceptibility artifacts obscured the fluid-filled tube at 1.5 T and 3 T. Susceptibility artifact size was calculated for each sequence within each magnet class. In vivo analysis included 42 patients postcholecystectomy who underwent MRC at either 1.5 T or 3 T. In vitro, mean area of susceptibility artifacts was 104 mm2 on 3-T and 75 mm2 on 1.5-T MR imaging (MRI). While surgical clips within a 2-mm range impaired visualization of the fluid-filled tube on 1.5-T MRI, this range increased to 4 mm on 3-T MRI. In vivo, MRC image quality was impaired by susceptibility artifacts in three of 21 cases at 3 T and in two of 21 cases at 1.5 T. Overall, biliary pseudo-obstructions due to susceptibility artifacts from cholecystectomy surgical clips were not substantially more common on 3-T MRC in clinical practice, and patients with a history of prior cholecystectomy should not be excluded from a 3-T MRC.
    European Radiology 11/2006; 16(10):2309-16. DOI:10.1007/s00330-006-0234-1 · 4.34 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This retrospective study was conducted to determine the incidence of sepsis at our institution after percutaneous drainage of a hepatic abscess. Thirty-three patients with a hepatic abscess treated using percutaneous aspiration and drainage from 1995 to 2000 were identified from a search of the interventional database. The patients' charts and CT images were reviewed independently by two radiologists for clinical presentation, relevant medical history, pre- and postprocedure antibiotic regimens, and clinical course after percutaneous aspiration and drainage. The preprocedure images were reviewed for the location and morphology of the abscess. The procedure details including percutaneous approach, guidance technique, catheter size, and immediate postprocedure complications were reviewed. Of the 33 patients, 14 patients underwent only needle aspiration of the abscess. In six (43%) of these 14 patients, the abscesses resolved with aspiration and appropriate antibiotic treatment alone. Eight (57%) of the patients who had aspiration of the abscess initially went on to have drainage catheters placed within a 72-hr period. Nineteen patients had drainage catheters placed from the onset. Of these, 17 patients (89%) had abscess resolution. Of the 27 patients who had catheters placed, a total of seven patients (26%) developed clinical symptoms of septicemia after catheter placement, but all patients, at least initially, responded to supportive treatment. Two patients died from septicemia 3-6 weeks after the procedure. None of the patients who underwent aspiration only developed postprocedure septicemia. After placement of a percutaneous drainage catheter in a hepatic abscess, there is a significant risk (26%) of postprocedure sepsis. Although it appears to be a random and unpredictable event in our small series, interventional radiologists and referring physicians should be aware of the risk of sepsis after percutaneous drainage of hepatic abscess.
    American Journal of Roentgenology 06/2006; 186(5):1419-22. DOI:10.2214/AJR.04.1914 · 2.74 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To compare the performance characteristics of various single-lumen all-purpose pigtail drainage catheters. The following parameters were compared: flow rates between catheters of the same size, whether changing the fluid viscosity has any effect on catheter comparisons, the effect on flow of leaving an open three-way stopcock in the drainage pathway, the tendency of the catheters to kink, and catheter patency after kinking, as measured according to flow. All-purpose 8.0-, 8.3-, and 8.5-F (collectively referred to as 8-F); 10.0-, 10.2-, and 10.3-F (collectively referred to as 10-F); and 12.0-F pigtail drainage catheters from three manufacturers were evaluated. Data were compared by using two-tailed t tests after normal distributions were confirmed. P < .05 was considered to represent a significant difference. At comparison of the 8-F catheters, the C.R. Bard catheters demonstrated better flow rates than the Cook and Boston Scientific devices. Among the 10-F catheters, there were no significant differences in the flow rates of fluid with viscosity equivalent to that of water between the C.R. Bard and Boston Scientific catheters; however, both these catheter types demonstrated significantly (P < .05) better flow rates than the Cook devices. Among the 12-F catheters, the C.R. Bard catheters demonstrated significantly (P < .05) better flow rates than the other two catheter types. Changing the fluid viscosity caused no changes in comparison results. In all catheter groups, the presence of a stopcock significantly (P < .05) impaired flow. None of the evaluated catheters demonstrated a clear advantage in terms of patency or susceptibility to kinking. At comparison of the in vitro performances of catheters from different manufacturers, the C.R. Bard 8.0-F and Cook 10.2-F catheters had comparable flow rates, and flow rates through the C.R. Bard and Boston Scientific 10.0-F catheters were comparable to flow rates through the Cook and Boston Scientific 12.0-F catheters. Varying viscosity had no effect on comparisons of catheter flow rates; however, a stopcock between the vacuum source and the catheter was noted to impair flow rates in all brands and sizes of evaluated catheters.
    Radiology 04/2006; 238(3):1057-63. DOI:10.1148/radiol.2383050578 · 6.21 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To retrospectively assess the added value of coronal reformations of the abdomen and pelvis from isotropic voxels by using 16-section multi-detector row computed tomography (CT) for the diagnosis of small-bowel obstruction (SBO). This HIPAA-compliant study was approved by the institutional review board of this medical center with a waiver of informed consent. One hundred consecutive patients (40 men and 60 women; mean age, 55 years) suspected of having SBO and abdominal pain underwent 16-section multi-detector row CT with coronal reformations. Twenty-nine patients had a final diagnosis of SBO, and 71 patients did not. Three independent readers blinded to the diagnosis interpreted the CT scout scan, then transverse scans alone, and then transverse plus coronal scans for the presence of SBO and abnormal wall enhancement. Confidence was scored with a 1-5 scale (1 = absent, 5 = present). Mean sensitivity and specificity of CT scout alone, transverse CT alone, and transverse plus coronal CT for the diagnosis of SBO were 88% and 86%, 87% and 87%, and 87% and 90%, respectively (not significant). In patients without SBO, transverse plus coronal CT enhanced confidence in the exclusion of SBO (P = .01). In patients with SBO, transverse plus coronal CT enhanced confidence in the diagnosis of SBO and identification of abnormal wall enhancement (P = .01). Transverse 16-section multi-detector row CT data sets are an excellent test for the diagnosis of SBO, while the addition of coronal reformations obtained from these isotropic data sets adds confidence to the diagnosis and exclusion of SBO.
    Radiology 02/2006; 238(1):135-42. DOI:10.1148/radiol.2381050489 · 6.21 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Compare pelvic morphology between asymptomatic African-American and white nulliparous women. Resting supine T2-weighted magnetic resonance (MR) images were obtained in 12 African-American (AA) and 10 white American (WA) women without pelvic floor dysfunction. Three-dimensional models were reconstructed from the MR images by a masked investigator, and predefined bony and soft tissue pelvic floor parameters were measured and compared. Nonparametric statistics were used, with significance considered at P < .05. Subjects were similar in age and body mass index. Levator ani volume was significantly greater in the AA versus the WA group (mean = 26.8 vs 19.8 cm3, P = .002). The levator-symphysis gap was smaller in the AA (left-18.2, right-18.8 mm) versus the WA group (22.4, 22.6 mm, P = .003, .048) on the left and right. Significant differences were seen in bladder neck position, urethral angle, and the pubic arch angle. The increased muscle bulk and closer puborectalis attachment seen among the African-American nulliparous women may impact the development of pelvic floor dysfunction. These findings need further study.
    American journal of obstetrics and gynecology 12/2005; 193(6):2035-40. DOI:10.1016/j.ajog.2005.06.060 · 3.97 Impact Factor
  • American Journal of Roentgenology 05/2005; 184(4):1178-80. DOI:10.2214/ajr.184.4.01841178 · 2.74 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: PURPOSE To test the hypothesis that coronal reformations obtained with isotropic MDCT data sets add in the diagnosis and characterization of small bowel obstruction (SBO). METHOD AND MATERIALS From June 2003 to January 2004, 50 consecutive patients with suspected small bowel obstruction underwent 16-slice MDCT (Lightspeed 16, GE Medical Systems) with coronal reformations. 13 patients had SBO, 37 had no obstruction. Protocol: oral contrast; 150 mL iopamidol at 3mL/second; 16x0.625mm, pitch 1.75, 17.5mm/rotation, 0.5 seconds. Axial images were reconstructed first at 5mm at 5mm intervals and second at 06.25mm at 0.5 mm intervals, and further reformatted coronally at 3 mm at 5 mm intervals. On a workstation (AW, GE Medical Systems), three independent blinded reviewers evaluated the CT scout, followed by the axial images alone and finally the coronal reformations combined with the axial images. Images were evaluated for confidence of recognition of SBO, identification of the cause and location of the transition point, and presence of pneumatosis, ascites, and wall thickening. Confidence was scored on a 1-5 scale (1 = absent, 5 = present). Scores were compared using the Signed Rank test and Receiver Operating Characteristics (ROC). RESULTS Mean sensitivity/specificity of CT scout alone, axial CT alone and axial combined with coronal CT for the diagnosis of SBO was 87%/85%, 79%/86%, and 82%/88%, respectively (not significant). The area under the ROC for the axials and the axials combined with coronals was similar for all three readers (mean axial: 0.94; mean axial/coronal: 0.93, not significant). Axials/coronals were similar to axials alone for both confidence in diagnosing SBO and in indentification of pneumatosis, wall thickening, and ascites. CONCLUSIONS 16-slice MDCT axial and coronal reformations are equally sensitive and specific for diagnosing SBO. While coronal reformations provide a novel perspective for SBO, the coronals do not add confidence to the diagnosis of SBO. DISCLOSURE E.K.P.: Consultant for General Electric Medical Systems
    Radiological Society of North America 2004 Scientific Assembly and Annual Meeting; 11/2004
  • [Show abstract] [Hide abstract]
    ABSTRACT: LEARNING OBJECTIVES This poster aims to familiarize the radiologist with the normal appearance, the different types and locations of the Artificial Urethral Sphincter (AUS) cuffs and common complications. Correlation with CT and urethroscopy/ cystoscopy images will also be provided. ABSTRACT Incontinence is a significant problem in post prostatectomy patients. AUS has achieved its greatest utility in the treatment of these patients with post prostatectomy incontinence. The current models consists of a pump combining two valves, resistor and a deactivation button, a surface treated urethral cuff made of silicone elastomer available in 12 sizes, kink resistant and color coded tubing and a pressure controlled balloon reservoir that comes in various pressure ranges. The cuffs may vary by number (tandem cuffs) and location (transcorporal, distal and proximal). Common complications include, cuff atrophy, pump malfunction, erosion, cuff and pump leak and change of reservoir position. Radiological evaluation of an AUS is an important means of trouble shooting a malfunctioning sphincter if the reservoir was filled with contrast material. Radiograph of the pelvis is the single most important diagnostic study in such situations.
    Radiological Society of North America 2004 Scientific Assembly and Annual Meeting; 11/2004
  • [Show abstract] [Hide abstract]
    ABSTRACT: PURPOSE To evaluate the potential of magnetic resonance cholangiography (MRC) at a field strength of 3 Tesla compared to the standard field strength of 1.5 Tesla. METHOD AND MATERIALS A standardized MRC sequence protocol was applied to ten healthy male volunteers (mean age � SD: 34 � 4.4 years) who underwent both MR scans within two hours in an alternating fashion using dedicated circular polarized torso coils (1.5 Tesla Siemens Magnetom Symphony, 3.0 Tesla Siemens Magnetom Trio). The sequence protocol included: Breath-hold single slice RARE (slice thickness [ST] 50 mm, orientation: coronal, and � 20� oblique coronal); breath-hold multi-slice HASTE (ST 3 mm, coronal only), and non-breath-hold, respiratory triggered 3D fast spin echo [3D-FSE] T2-weighted sequence (ST 1mm, 60 slices per slab, coronal only). Maximum intensity projections were generated from each multi-slice data set. Common bile duct to periductal tissue contrast-to-noise ratios were compared at 1.5 and 3.0 Tesla. Qualitative image analysis was performed by three independent readers. Qualitative analysis included delineation of the extra and intrahepatic biliary anatomy with specific attention given to the presence (or absence) of cystic or intrahepatic ductal variants using a 4-point confidence scale. Statistical analysis consisted of the paired Student�s t-test and the signed rank test. RESULTS Contrast-to-noise ratios between the common bile duct and the periductal tissue were higher at 3 Tesla. P-values were 0.02, 0.08 and 0.03 for RARE, HASTE and 3D-FSE, respectively. Within each magnet class, the 3D-FSE offered the best contrast-to-noise and qualitative analysis. Superiority of the 3D-FSE was statistically significant in all but one analysis (1.5T; 3D-FSE vs. HASTE). Three of ten volunteers had intrahepatic biliary variants which were detected with a higher level of confidence (p = 0.01) on the 3 Tesla compared to the 1.5 Tesla system. CONCLUSIONS Compared to MRC at 1.5 Tesla, MRC at 3 Tesla offers improved CNR and a higher level of confidence for depicting intrahepatic variants.
    Radiological Society of North America 2004 Scientific Assembly and Annual Meeting; 11/2004
  • American Journal of Roentgenology 11/2004; 183(4):899-906. DOI:10.2214/ajr.183.4.1830899 · 2.74 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To prospectively evaluate a technique for optimizing aortoiliac enhancement at multi-detector row helical computed tomography (CT) with both the scanning delay and contrast medium dose determined by using an interactive method. Forty-five patients with abdominal aortic aneurysm were randomized to undergo multi-detector row helical CT with either an interactive protocol (n = 23) or a standard protocol (n = 22). Scanning delays in all patients were determined with automated triggering. Patients in the standard protocol group received 150 mL of contrast medium intravenously at 4 mL/sec. The same injection rate was used for the interactive protocol group, but the dose was reduced with discontinuation of injection at start of scanning. Quantities of contrast medium used and contrast-enhanced aortic attenuation achieved were compared. Aortoiliac enhancement was evaluated qualitatively by using a five-point scale (1 = poor, 5 = excellent). Quantitative and qualitative data were analyzed with the two-tailed t test and Wilcoxon rank sum test, respectively, to determine significance of differences (P <.05). Data from six patients were excluded because of technical errors. Data were analyzed from 20 patients in the interactive protocol group and 19 in the standard protocol group. Mean contrast medium volume was 107 mL +/- 20 (standard deviation) in the interactive protocol group and 148 mL +/- 3 in the standard protocol group (P <.001). Mean contrast-enhanced attenuation at initial, peak, and final measurements was 257 HU +/- 38, 285 HU +/- 46, and 269 HU +/- 54, respectively, for the interactive protocol group, and 261 HU +/- 65, 288 HU +/- 66, and 269 HU +/- 61 for the standard protocol group (P >.05). Mean qualitative enhancement scores for interactive and standard protocol groups were 4.47 and 4.44, respectively (P =.47). The interactive method is a simple, efficient, and reproducible way to optimize aortoiliac enhancement while reducing contrast medium dose.
    Radiology 09/2004; 232(3):854-9. DOI:10.1148/radiol.2323031006 · 6.21 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to compare hepatic enhancement characteristics using two different contrast media injection protocols with multidetector helical computed tomography. Twenty-three patients with known or suspected liver lesions scheduled to undergo biphasic hepatic multidetector helical computed tomography were randomized into one of two groups: (1) 150 mL of iopamidol (300 mgI/mL) at 5 mL/second, or (2) 100 mL of iopamidol (370 mgI/mL) at 4 mL/second. Unenhanced images were acquired initially, followed by both hepatic arterial phase (scan delay, 33 seconds) and portal venous phase (PVP; scan delay, 65 seconds) imaging. Three abdominal radiologists independently graded the images on a scale from 1-5 for enhancement and overall scan quality. Time-attenuation curves were generated from operator-defined region-of-interest measurements of liver parenchyma and aorta. Qualitatively, the three reviewers found no significant difference between the two study groups in terms of overall scan quality (P = .23) or aortic enhancement (hepatic arterial phase, P = .9; PVP, P = .24). However, liver enhancement during the PVP was considered to be less in the Isovue 370 group (P = .04). Quantitatively, during the hepatic arterial phase, there was no statistically significant difference between the two injection protocols comparing either aortic or hepatic parenchymal enhancement (P = .62 and .80, respectively). During the PVP, these differences were statistically significant, with both aortic and hepatic parenchymal enhancement lower in the Isovue 370 group (P < .01 and P = .04, respectively). It is important to consider the amount of iodine injected per second and the duration of the injection when setting up protocols to achieve target organ enhancement. 100 mL of iopamidol 370 at 4 mL/second can be used to obtain images of the liver with good diagnostic quality compared to more conventional protocols using 150 mL of iopamidol 300 at 5 mL/second. However, the degree of liver parenchymal enhancement during the PVP using the latter injection scheme is lower, which in turn could potentially reduce hepatic lesion conspicuity.
    Academic Radiology 03/2004; 11(3):267-71. DOI:10.1016/S1076-6332(03)00675-5 · 2.08 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The objective of our study was to determine the usefulness of sonographic guidance for biopsy of mesenteric masses. Twenty-five sonographically guided percutaneous biopsies of mesenteric masses were performed in 23 patients. Biopsies were performed with an 18-, 20-, or 22-gauge self-aspirating needle or core biopsy device. Final pathology results and patient medical records were reviewed for biopsy accuracy and complications. A biopsy was considered successful if a specific benign or malignant diagnosis was rendered by the pathologist or if surgical-pathologic confirmation was obtained. Open surgical biopsy was performed after sonographically guided biopsy in 13 patients and led to 12 concordant diagnoses (nine true-positives and three true-negatives) and one discordant diagnosis (false-negative). Specific pathologic diagnosis was rendered for the 10 percutaneous biopsies that were not confirmed by surgical biopsy: five biopsies matched known primary malignancies, consistent with metastases; four biopsies revealed primary tumors, and one biopsy revealed chronic inflammation (nine true-positives and one true-negative). Two biopsies were nondiagnostic because of insufficient material (n = 1) and necrotic tumor (n = 1). In the biopsies with diagnostic tissue specimens, sonographically guided biopsy achieved a sensitivity of 95% (18/19) and specificity of 100% (4/4) for allowing neoplastic tissue to be distinguished from nonneoplastic tissue. Complications included a mesenteric hematoma and abdominal wall cellulitis. Percutaneous biopsy of mesenteric masses is a useful and safe procedure.
    American Journal of Roentgenology 07/2003; 180(6):1563-6. DOI:10.2214/ajr.180.6.1801563 · 2.74 Impact Factor