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Biomedical subjects

Leo P Lawler

Publications and source records attributed to Leo P Lawler.

At least 19 recordsLinked to original sources
PubMed2006

Diagnosis of primary sclerosing cholangitis: a blinded comparative study using magnetic resonance cholangiography and endoscopic retrograde cholangiography.

BACKGROUND: We hypothesized that magnetic resonance cholangiography (MRC) may have less accuracy for the diagnosis and the assessment of the severity of primary sclerosing cholangitis (PSC) than endoscopic retrograde cholangiography (ERC). OBJECTIVE: The aim of this study was to determine the diagnostic accuracy and interobserver agreement of both ERC and MRC in PSC. DESIGN: A case-control study. SETTING: University Hospital. PATIENTS: ERCs and MRCs of 36 patients with PSC and 51 controls (normal/other biliary tract diseases) were read in an independent, blinded, and random fashion by 2 magnetic resonance radiologists and 2 interventional endoscopists by using a previously validated classification system. Readers had no access to clinical history, laboratory results, or patient mix. RESULTS: Extrahepatic ductal (EHD) and intrahepatic ductal (IHD) visualization was excellent in 64% of 66% of MRCs and 86% of 74% of ERCs. Sensitivity and specificity for diagnosis of PSC for readers 1 to 4 were 91% and 85%, 88% and 90%, 81% and 96%, and 83% and 96%. respectively. Receiver operating curve values were excellent for all readers (all >0.9). Interobserver agreement (kappa statistics) for the diagnosis of PSC (MRC, 0.83; ERC, 0.73) and for identifying the presence of IHD strictures (MRC, 0.64; ERC, 0.86) was good for both modalities, but only ERC (ERC, 0.55; MRC, 0.36) was good for the presence and the severity of EHD strictures. When assessment of disease severity was limited to the 36 patients with PSC, interobserver agreement was very poor for both MRC (0.23 and 0.07 for EHD and IHD, respectively) and ERC (0.24 and 0.34 for EHD and IHD, respectively). LIMITATIONS: The retrospective case-control study made it difficult to assess the impact of the diagnosis on patient management. CONCLUSIONS: ERC and MRC were comparable for diagnosing PSC, with very good interobserver agreement for the diagnosis of PSC and IHD strictures. Only ERC had good agreement for EHD strictures. Interobserver agreement was very poor for both MRC and ERC when disease severity of PSC was assessed.

Bile Ducts, Extrahepatic↗
PubMed2006

Transrectal US-guided seminal vesiculography and ejaculatory duct recanalization and balloon dilation for treatment of chronic pelvic pain.

Ejaculatory duct obstruction (EDO) is an uncommon but correctable cause of infertility and male chronic pelvic pain. The condition is thought to be underdiagnosed, but the increased application of noninvasive imaging tools, specifically transrectal ultrasonography (US), has lead to greater recognition of EDO. Moreover, the development of minimally invasive therapies now offers comprehensive evaluation and treatment options with low morbidity for select patient groups. This report describes the technique of transrectal US-guided seminal vesiculography, percutaneous recanalization, and ejaculatory duct balloon dilation for EDO as a treatment for male chronic pelvic pain.

Adult↗
PubMed2006

MDCT of intraductal papillary mucinous neoplasm of the pancreas: evaluation of features predictive of invasive carcinoma.

OBJECTIVE: The purpose of our study was to evaluate factors predictive of the presence of invasive carcinoma associated with intraductal papillary mucinous neoplasm (IPMN) of the pancreas on MDCT. MATERIALS AND METHODS: Preoperative MDCT of 36 consecutive patients (23 men, 13 women; mean age, 66.6 years) who had undergone surgical resection and had a pathologic diagnosis of IPMN were retrospectively assessed. CT was performed with a 4-MDCT scanner with 120 mL of IV contrast material at an injection rate of 3 mL/sec. Arterial and venous phase images were acquired at 25 and 50-60 sec from the start of IV contrast administration. Type of ductal involvement, location, tumor size in branch duct type and combined type lesions, caliber of the main pancreatic duct, caliber of the common bile duct or common hepatic duct, and solid appearance of the lesion were assessed on CT and correlated with pathologic findings for invasive carcinoma. RESULTS: Pathologic analysis revealed carcinoma in situ in seven patients (19%) and invasive carcinoma in 15 patients (42%) arising from the IPMN. With invasive carcinoma, the size of the tumor in branch duct type and combined type, and the caliber of the main pancreatic duct were significantly larger compared with the lesions without invasive carcinoma (4.7 +/- 1.7 cm vs 2.6 +/- 1.4 cm [p = 0.0007] and 9.3 +/- 5.5 mm vs 4.6 +/- 4.1 mm [p = 0.006], respectively). A solid mass (p < 0.001), dilatation of the common bile duct or common hepatic duct (> or = 15 mm), and the presence of a stent (p = 0.0004) were correlated with the presence of associated invasive carcinoma. CONCLUSION: MDCT helped to predict invasive carcinoma associated with IPMN.

Adenocarcinoma, Mucinous↗
PubMed2005

Diagnostic radiology and nuclear medicine.

The diagnosis and accurate staging of esophageal adenocarcinoma remains one of the greatest challenges for non-invasive imaging techniques. All modalities have limitations and require a rational application of combined tools in order to assess the extent of loco-regional tumor and distant metastatic disease. The fundamental role remains defining organ-confined disease and mapping non-organ confined disease. Endoscopic ultrasound combined with multislice computed tomography (CT) is the mainstay of morphologic loco-regional staging. In recent years, functional metabolic 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) has emerged as a particularly useful adjunct to detect occult metastatic disease, to predict response to neoadjuvant therapy and to document recurrent disease. The current imaging algorithm and new developments in imaging assessment will be reviewed.

Adenocarcinoma↗
PubMed2005

Evaluation of the renal venous system on late arterial and venous phase images with MDCT angiography in potential living laparoscopic renal donors.

OBJECTIVE: The objective of our study was to assess whether both renal arteries and renal veins can be evaluated using single-phase MDCT data sets alone to eliminate the need for both arterial and venous phase data sets. MATERIALS AND METHODS: One hundred consecutive potential living renal donors who underwent 4-MDCT were evaluated. CT was performed with 120 mL of IV contrast material at an injection rate of 3 mL/sec. Both late arterial and venous phase acquisitions were obtained at 25 and 55 sec from the start of IV contrast injection, respectively. The number of the right and left renal veins and its anatomic variations were assessed by two reviewers. Late arterial phase images were evaluated initially, and then venous phase images were analyzed to assess opacification of the renal vein and to see whether venous phase data sets changed or added information about the venous anatomy as seen on late arterial phase images. RESULTS: The retroaortic left renal vein was found in two subjects, and the circumaortic left renal vein was detected in three subjects. The renal veins were adequately opacified on late arterial phase images in all subjects. There were six subjects who had a normal left renal vein with a small posterior branch coursing posterior to the aorta and draining into the inferior vena cava, which were difficult to differentiate from the lumbar vein or ascending lumbar vein; in three of these six subjects, the small posterior branch was opacified only on venous phase images. CONCLUSION: Late arterial phase images obtained at 25 sec after the start of contrast injection can reveal the renal vein anatomy except for a small posterior branch of the left renal vein difficult to differentiate from the lumbar or ascending lumbar vein, as seen in three subjects. The data suggest that venous phase imaging is not necessary for the evaluation of renal vein anatomy.

Adult↗
PubMed2005

MDCT evaluation of the coronary arteries, 2004: how we do it--data acquisition, postprocessing, display, and interpretation.

OBJECTIVE: Cardiac CT is rapidly becoming part of clinical practice. The objective of this article is to discuss and illustrate the current practice of coronary artery MDCT, including data acquisition, postprocessing, image display, and interpretation. The practice described reflects our experience with a series of patients referred in routine clinical practice. CONCLUSION: The reader should gain an insight into the current clinical application of coronary artery CT.

Contrast Media↗
PubMed2004

CT angiography: principles, techniques and study optimization using 16-slice multidetector CT with isotropic datasets and 3D volume visualization.

Significant advances in computed tomography (CT) scanner technology as well as 3D imaging software and hardware have resulted in amazing improvements in CT imaging of blood vessels. CT angiography has now been incorporated into daily practice and in may cases has replaced conventional angiography. CT angiography has also resulted in new applications for CT such as coronary angiography. This article discusses the current state of the art of 3D CT angiography and reviews the literature. Extensive case examples are included.

Angiography↗
PubMed2003

Computer-assisted detection of pulmonary nodules: preliminary observations using a prototype system with multidetector-row CT data sets.

The continued revolution in multidetector-row CT (MDCT) scanning increases the quality of lung imaging but at the cost of a greater burden of data for review and interpretation. This article discusses our preliminary experience with prototype software for lung nodule detection and characterization using MDCT data sets. We discuss the potential role of computer-assisted detection (CAD) as applied to the automatic detection of lung nodules. We also review the process of CAD, outline its potential results, and explore how it may fit into existing radiology practice. Finally, we discuss MDCT data-acquisition parameters and how they may affect the performance of CAD.

Algorithms↗
PubMed2003

MR imaging of the bladder.

MR imaging of the bladder can now be routinely and easily performed with consistent quality. The latest techniques provide high-resolution images of the soft tissue contrast and the ability to perform dynamic contrast imaging and functional pelvic floor studies. MR imaging fits in as a complimentary tool to cystoscopy and to conventional pelvic floor dynamic studies and can provide a unique imaging perspective of the bladder. It is important, however, to remain cognizant of the limitations of its use in tumor detection and discrimination.

Contrast Media↗
PubMed2003

Thoracic venous anatomy multidetector row CT evaluation.

Two-dimensional CT angiography provides much information of the systemic and pulmonary thoracic veins. The combination of MDCT and volume-rendering techniques postprocessing provides higher-quality data sets and a method fully to harness the potential for image display and interpretation. Although this may not radically alter sensitivity for detection of systemic or pulmonary venous pathology it does provide a more comprehensive and sophisticated evaluation through volume acquisition and interpretation.

Angiography↗
PubMed2003

Multidetector row computed tomography of the aorta and peripheral arteries.

MDCT represents a significant advance on SDCT and the advantages it brings are particularly clear in CTA applications. It allows cost effective assessment of longer segments of vascular territories to be imaged with higher spatial, contrast, and temporal resolution. It has replaced SDCT as the new CT standard and its technical abilities are rapidly approaching the temporal resolution of EBCT. With 3-D post processing tools its main benefit is in imaging studies customized to the patient's pathology, with greater measurement accuracy and reliable longitudinal assessment. MDCTA is increasingly applied not to individual vascular territories but to a complete assessment dictated by the pathology, such as the entire aorta and branch vessels in aneurysm evaluation and the aorta and the coronary arteries in dissection cases or the vascular and non-vascular chest in acute chest pain. Greater accuracy of vessel assessment will lead to a refinement of interventional and surgical techniques for an individual patient and facilitates conservative management of conditions that can be reliably monitored non-invasively and the development of intervention criteria. MDCTA will continue to increase its major role in peripheral vascular evaluation in the future though its reliability in assessing small vessels below the knee and in the foot remains to be conclusively proven to obviate the need for diagnostic catheter angiography.

Aortic Dissection↗
PubMed2003

Effects of nonionic intravenous contrast agents at PET/CT imaging: phantom and canine studies.

PURPOSE: To investigate the effects of intravenous contrast agents on quantitative values obtained with a combined positron emission tomographic (PET) and computed tomographic (CT) scanner by using several phantoms and a dog. MATERIALS AND METHODS: Fluorine 18 fluorodeoxyglucose (FDG) was mixed with different concentrations of contrast agent with the same syringe (phantom 1), and the phantom was scanned. After image reconstruction with various attenuation maps, radioactivity concentrations were compared. Then, FDG solutions with (phantom 2) or surrounded by (phantom 3) various concentrations of contrast agent were scanned repeatedly, and radioactivity concentration was compared. Finally, PET and CT with and without contrast agent were performed in a dog. PET images were reconstructed by using different attenuation maps, and radioactivity concentrations were compared. The radioactivity concentration on germanium 68 (68Ge)-based corrected images was regarded as standard, and percentage bias, defined as difference divided by measured activity of 68Ge-based corrected images, was assessed. The relationship between the concentration of contrast agent and the percentage bias was assessed with the Pearson coefficient r, and the significance of correlations was evaluated with the Fisher z test. RESULTS: All phantom studies demonstrated that presence of a contrast agent resulted in overestimation of emission data. CT numbers showed a strong positive correlation with the percentage bias in phantoms 2 (r = 0.999) and 3 (r = 0.987); the maximum percentage bias at 1,360 HU reached approximately 45%. These effects were independent of FDG concentration. In a canine model, presence of a contrast agent also increased emission activity, but the percentage bias was less than 15% in the liver and smaller in all other organs except the kidney (26%). CONCLUSION: High concentrations of a contrast agent caused considerable overestimation of apparent tracer activity in phantom studies; however, the emission bias was relatively modest in vivo, except in areas with very high contrast agent concentrations.

Animals↗
PubMed2003

Multidetector CT angiography for preoperative evaluation of living laparoscopic kidney donors.

OBJECTIVE: The purpose of this study was to determine the accuracy of multidetector CT (MDCT) angiography as the primary imaging technique in the evaluation of living kidney donors. SUBJECTS AND METHODS: Seventy-four consecutive living kidney donors (30 men, 44 women; mean age, 41.7 years) who underwent MDCT were evaluated. CT examination was performed with 120 mL of IV contrast material at an injection rate of 3 mL/sec and a pitch of 6. In every case, arterial and venous phase volumetric data sets were acquired at 25 and 55 sec, respectively. Scans were reconstructed at 1-mm intervals for three-dimensional (3D) imaging using a volume-rendering technique. Axial CT images and 3D CT angiography were evaluated prospectively by one reviewer and retrospectively by two reviewers who had no knowledge of surgical results. Surgical correlation for the location of primary and accessory renal arteries, early branching of the renal arteries, and renal vein anomalies was made. RESULTS: Seventy-two subjects underwent left nephrectomy, and two subjects underwent right nephrectomy because supernumerary left renal arteries were detected on preoperative CT angiography. Eighteen supernumerary renal arteries (two arteries to 16 kidneys and three arteries to one kidney) to 74 kidneys underwent nephrectomy. CT and surgical findings agreed in 93% of subjects (the average of three reviewers; range, 89-97%). Two small accessory renal arteries were missed by all three reviewers. Those arteries were diminutive and were thought to be insignificant by the surgeons. Early branching of the renal arteries was shown in 14 arteries, and CT and surgical findings agreed in 96% (the average of three reviewers; range, 93-97%). Renal vein anomalies were present in eight subjects, and CT and surgical findings agreed in 99% of the cases (range, 96-100%). CONCLUSION: MDCT angiography is highly accurate for detecting vascular anomalies and providing anatomic information for laparoscopic living donor nephrectomy.

Adult↗