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Biomedical subjects

Dushyant V Sahani

Publications and source records attributed to Dushyant V Sahani.

At least 19 recordsLinked to original sources
PubMed2007

16-MDCT angiography in living kidney donors at various tube potentials: impact on image quality and radiation dose.

OBJECTIVE: The objective of our study was to compare the performance of 16-MDCT angiography at various peak kilovoltage (kVp) settings and the impact of the different settings on image quality and on radiation dose in adult kidney donors. MATERIALS AND METHODS: Sixty-two renal donors (32 men, 30 women) who underwent 16-MDCT were divided into three groups: 18 subjects were studied at 140 kVp (group A); 20, at 120 kVp (group B); and 24, at 100 kVp (group C). Other constant scanning parameters were as follows: detector collimation, 0.625 mm; table feed, 9.375 mm/rotation; gantry rotation time, 500 milliseconds; and automatic current tube modulation (ATCM) using a noise index of 15. A total of 135-140 mL of iodinated contrast material (300 mg I/mL) was administered at 5 mL/s via an 18-gauge cannula, and arterial phase scanning was initiated using a bolus-tracking technique. Two observers evaluated image quality of the axial and 3D images and the visibility of branch order in the superior mesenteric artery (SMA) and renal arteries. Attenuation (in Hounsfield units [H]) in the aorta, SMA, and main renal artery was also measured by placing a region of interest. Radiation dose measurements were based on the scanner-generated CT dose index volume (CTDI(vol)). Each parameter tested was compared among the three groups using a nonparametric analysis of variance test, and a p value of 0.05 was considered significant. RESULTS: Differences in the quality of the axial images existed between groups A and C (p < 0.001) and between groups B and C (p < 0.01); the image quality of the 3D images and the visibility of branch order in the SMA and renal arteries were comparable for all groups. The difference in mean attenuation of the aorta, SMA, and renal arteries was significant between groups A and C (p < 0.001) and between groups B and C (p < 0.01). All groups had 100% diagnostic accuracy in identifying the number of renal arteries on the side of nephrectomy. The mean radiation dose in CTDI(vol) was 25 +/- 3 mGy at 140 kVp, 17 +/- 4 mGy at 120 kVp, and 12 +/- 3 mGy at 100 kVp (p < 0.001). CONCLUSION: Our initial observations suggest that the image quality of 16-MDCT angiography performed at 120 kVp is similar to that of CT angiography (CTA) performed at 140 kVp in adult kidney donors but with a significant radiation dose reduction. CTA at 100 kVp results in higher image noise but provides diagnostically acceptable images with significant radiation dose reduction compared with CTA at 120 or 140 kVp.

Adult↗
PubMed2006

EUS-guided injection of paclitaxel (OncoGel) provides therapeutic drug concentrations in the porcine pancreas (with video).

BACKGROUND: OncoGel (ReGel/paclitaxel) is an intralesional injectable formulation of the chemotherapeutic drug, paclitaxel, for local tumor management. OBJECTIVE: The aim of this study was to determine if a minimally invasive EUS-guided injection of paclitaxel, bound to a thermosensitive gel carrier, would lead to therapeutic tissue concentrations of the chemotherapeutic agent in the porcine pancreas. DESIGN: Eight Yorkshire breed pigs were sedated by general anesthesia and OncoGel was injected, under EUS-guidance, with a 22-gauge needle into the tail of the pancreas. MAIN OUTCOME MEASUREMENTS: During the 7-day (n = 4) or 14-day (n = 4) observational period, the animals were monitored by serum levels of amylase and lipase, and by a CT on day 4. The outcome was determined by gross and microscopic evidence of inflammation of the pancreas, clinical tolerance, and quantitation of tissue paclitaxel concentrations. RESULTS: Eight pigs underwent injection of 1, 2, 3, or 4 mL OncoGel (6 mg paclitaxel per 1 mL OncoGel) (n = 2 per group). An intrapancreatic hyperechoic focus, with an average diameter of 2.1 +/- 0.8 cm, was visible by EUS, and a hypodense area in the tail of the pancreas was visible by contrast CT. Clinically, the animals appeared to tolerate the procedure without sequelae. Blood levels of amylase and lipase were normal. At euthanasia, a depot of OncoGel, with an average diameter of 14.7 +/- 5.0 mm), was located both grossly and histologically in the pancreatic tail. After 14 days, clinically significant tissue concentrations of paclitaxel were detected at a distance of 30 to 50 mm from the depot in the animals that underwent an injection of 3 and 4 mL of the agent (n = 2). CONCLUSIONS: The EUS-guided injection of OncoGel into the pancreas of the pig provided high and sustained localized concentrations of paclitaxel. This technique is a potential minimally invasive local treatment option for unresectable pancreatic tumors.

Animals↗
PubMed2006

Effect of obesity on image quality: fifteen-year longitudinal study for evaluation of dictated radiology reports.

PURPOSE: To retrospectively assess the effect of obesity on image quality, as determined from dictated radiology reports filed between 1989 and 2003. MATERIALS AND METHODS: Institutional review board approval was obtained for this HIPAA-compliant study; informed consent was not required. Electronic records were searched for radiology reports with the phrase "limited due to body habitus" (hereafter, "habitus limited") filed between 1989 and 2003; reports were retrospectively reviewed. Habitus limited was qualified as the search phrase by auditing radiologic images and patient weights. Trends in the number of habitus-limited reports were calculated for each year, and linear regression analysis was performed. The number of habitus-limited reports was also compared between modalities within a year and within each modality across 15 years. The trend was correlated with the prevalence of obesity in Massachusetts by using the Pearson correlation coefficient. RESULTS: There was a significant difference (P < .001) between the weight of patients with habitus-limited reports and the weight of patients with reports that were not habitus limited. Overall, 7778 (0.15%) of 5 253 014 reports were habitus limited. Between 1989 and 2003, there was a linear increase of 0.010% per year (95% confidence interval: 0.007%, 0.013%; P < .001). There was a positive correlation between the increased number of habitus-limited reports and the increased prevalence of obese individuals in Massachusetts between 1991 and 2001. The modality most commonly associated with habitus-limited reports was abdominal ultrasonography. CONCLUSION: There was a small but progressive increase in the number of habitus-limited radiology reports between 1989 and 2003.

Adolescent↗
PubMed2006

Evaluation of living renal donors: accuracy of three-dimensional 16-section CT.

PURPOSE: To retrospectively assess the sensitivity and specificity of three-dimensional (3D) 16-section computed tomography (CT) in the evaluation of vessels, pelvicalyceal system, and ureters in living renal donors, with surgical findings as the reference standard. MATERIALS AND METHODS: This was a HIPAA-compliant study. Institutional review board approval was obtained for the review of subjects' medical records and data analysis, with waiver of informed consent. Forty-six renal donors (18 men, 28 women; mean age, 42 years) were examined with 16-section CT. Two blinded reviewers independently studied renal vascular and urographic anatomy of each donor CT scans by fist using 3D images alone, then transverse images alone, and finally transverse and 3D data set. Image quality, degree of diagnostic confidence, and time used for review were recorded. Sensitivity and specificity were calculated. RESULTS: For 3D images, transverse images, and transverse in conjunction with 3D data sets, the respective sensitivity and specificity of CT in evaluation of accessory arteries by reviewer 1 were 100% and 100%, 89% and 100%, and 100% and 100%, and those by reviewer 2 were 89% and 97%, 89% and 100%, and 89% and 100%; the respective sensitivity and specificity in evaluation of venous anomalies by reviewer 1 were 100% and 98%, 100% and 98%, and 100% and 98%, and those by reviewer 2 were 100% and 98%, 100% and 95%, and 100% and 98%. For focused comprehensive assessment of renal donors with 3D scans alone, a reviewer on average (average of reviewers 1 and 2) used 2.4 minutes per scan, demonstrated full confidence in 93%, and rated the quality as excellent in 76%. CONCLUSION: For focused assessment of renal vascular and urographic anatomy, review of 3D data set alone provides high sensitivity and specificity with regard to findings seen at surgery.

Adult↗
PubMed2006

Pancreatic cysts 3 cm or smaller: how aggressive should treatment be?

PURPOSE: To retrospectively determine the frequency of malignancy in small (< or =3 cm) pancreatic cysts, to evaluate whether cyst morphologic features can help predict the presence of malignancy, and to determine the natural history of small pancreatic cysts at follow-up imaging. MATERIALS AND METHODS: Institutional review board approval was obtained; informed patient consent was not required. By means of a computerized search, 510 patients with pancreatic cysts that had been detected at computed tomography (CT) or magnetic resonance (MR) imaging were identified. Cysts that were 3 cm or smaller at surgery or endoscopic ultrasonography (US)-guided cyst fluid aspiration and biopsy were included. Eighty-six patients-31 men and 55 women aged 24-89 years-fulfilled the criteria. Patients underwent surgery or were monitored with endoscopic US-guided cyst fluid analysis, cytologic analysis, and follow-up imaging. Imaging findings were compared with surgical and pathology records and with endoscopic US features. Positive predictive values (PPVs) for benignity and malignancy were calculated on the basis of cyst size and absence or presence of septa in the cysts. RESULTS: Forty-eight patients underwent surgery, and 38 were treated nonsurgically. Seventy-five patients had benign cysts; eight, borderline (malignant) neoplasms; and three, carcinoma in situ lesions. The PPV of small pancreatic cysts for prediction of benignity was 87% (75 of 86 patients). Thirty-six patients had unilocular cysts (35 with benign lesions, one with borderline neoplasm). The PPV of unilocular cysts for prediction of benignity was 97% (35 of 36 patients). Fifty patients had septated cysts; seven of these patients had borderline neoplasms, and three had carcinoma in situ lesions. For prediction of malignancy in small cysts, the PPV of septa was 20% (10 of 50 patients), which was significantly higher than the 3% (one of 36 patients) PPV of unilocular cysts (P = .042). No significant changes in cyst morphologic features were seen in patients who were followed up with imaging for a mean period of 21.8 months. CONCLUSION: The majority (n = 75) of small pancreatic cysts were benign. Thirty-six cysts were unilocular, and virtually all of these (n = 35) were benign. The presence of septa was associated with borderline or in situ malignancy in 20% (10 of 50) of cases.

Adult↗
PubMed2006

Intraductal papillary mucinous neoplasm of pancreas: multi-detector row CT with 2D curved reformations--correlation with MRCP.

PURPOSE: To retrospectively compare accuracy of multi-detector row computed tomography (CT), combined with two-dimensional (2D) curved reformations, and that of magnetic resonance (MR) cholangiopancreatography (MRCP) for characterization of intraductal papillary mucinous neoplasm (IPMN) as malignant, with pathologic examination as reference standard. MATERIALS AND METHODS: Institutional review board approval was obtained, informed consent was waived, and study was HIPAA compliant. Twenty-five patients (12 women, 13 men; age range, 44-88 years) with pathologically proved IPMN were examined with dual-phase CT with 1.25-mm-thick sections for pancreatic phase; 2D curved reformations along main pancreatic duct (MPD) were generated. T2-weighted MRCP included thick- and thin-slab single-shot fast spin-echo imaging and transverse fast spin-echo imaging. Two radiologists, blinded to surgical and pathologic findings, evaluated images for lesion location, septa, mural nodules, communication with MPD, extent and diameter of MPD dilatation, calcifications, and vascular encasement. Malignancy was suspected when one of the following was present: MPD diameter larger than 10 mm, mural nodules, vascular encasement, peripancreatic lymphadenopathy, or metastases. Sensitivity and specificity values for prediction of malignancy were calculated for CT and MRCP. Interobserver variability was determined (kappa analysis). RESULTS: Excellent correlation between modalities was observed. Cyst communication was seen in 20 and 21 of 24 branch pancreatic duct (BPD) IPMNs with CT and MRCP, respectively. Sensitivity, specificity, and accuracy for detection of malignancy were 70%, 87%, and 76% (CT) and 70%, 92%, and 80% (MRCP), respectively. Interobserver agreement was good to perfect for both readers in all comparisons (overall, kappa = 0.70-1.00). CONCLUSION: CT combined with 2D curved reformation can provide imaging details of IPMN, including communication of BPD IPMN with MPD, that are almost equivalent to those provided at MRCP. Presence of mural nodules, dilated MPD (>10-mm diameter), or thick septa at CT or MRCP may be used as independent predictors of malignancy.

Adenocarcinoma, Mucinous↗
PubMed2006

What is the current state-of-the-art imaging for detection and staging of cholangiocarcinoma?

Cholangiocarcinoma is an adenocarcinoma that arises from the bile duct epithelium and is the second most common primary hepatobiliary cancer, after hepatocellular cancer, with approximately 2,500 cases annually in the U.S. However, cholangiocarcinoma remains a relatively rare disease, accounting for <2% of all human malignancies. Although the entire biliary tree is potentially at risk, tumors involving the biliary confluence or the right or left hepatic ducts (hilar cholangiocarcinoma) are most common and account for 40%-60% of all cases. Most patients present with advanced disease that is not amenable to surgical treatment. The median survival time for patients with intrahepatic cholangiocarcinoma without involvement of the hilum varies among centers from 18-30 months. The median survival time for patients with perihilar cholangiocarcinoma is slightly less, varying from 12-24 months. Despite the overall poor prognosis, survival after surgical treatment of hilar cholangiocarcinoma has improved during the past 10-15 years. This review highlights the imaging features of cholangiocarcinoma, with particular emphasis on the imaging techniques that can best assess tumor resectability and guide the surgeon regarding the potential extent of resection required in operable candidates.

Bile Duct Neoplasms↗
PubMed2005

Distinguishing benign from malignant adrenal masses: multi-detector row CT protocol with 10-minute delay.

PURPOSE: To retrospectively evaluate the accuracy of precontrast attenuation, relative percentage washout (RPW), and absolute percentage washout (APW) in distinguishing benign from malignant adrenal masses at multi-detector row computed tomography (CT). MATERIALS AND METHODS: This HIPAA-compliant retrospective study had institutional review board approval; the need for informed consent was waived. One hundred twenty-two adrenal masses were evaluated in 99 patients (51 men, 48 women; age range, 37-86 years) who had undergone CT performed according to the study protocol and who either were given a pathologic diagnosis or underwent follow-up imaging. Unenhanced images were obtained before administration of 120 mL of an intravenous contrast agent with a 75-second scan delay. Delayed images were obtained after 10 minutes. RPW and APW were computed. Receiver operating characteristic (ROC) analysis was performed to compare mean attenuation and both RPW and APW. Analysis was first performed with the exclusion of pheochromocytomas, myelolipomas, and cysts. Precontrast attenuation criteria specific for benignity or malignancy were determined, and ROC analysis of results for the entire nonpheochromocytoma group was then performed. RESULTS: By using an RPW of 37.5% and excluding cysts and myelolipomas, all malignant lesions were detected with a sensitivity of 100% (17 of 17 lesions) and a specificity of 95% (90 of 95 lesions). Area under the binomial ROC curve (A(z)) values were 0.912, 0.985, and 0.892 for precontrast attenuation, RPW, and APW, respectively. Precontrast attenuation of less than 0 or more than 43 HU indicated benign and malignant entities, respectively. Incorporation of these criteria into the APW analysis yielded a sensitivity of 100% (17 of 17 lesions) and a specificity of 98% (93 of 95 lesions) for a threshold washout value of 52.0%. This attenuation-corrected APW generated the greatest A(z) value (ie, 0.988). Combining all the information available from the protocol yielded a sensitivity of 100% (17 of 17 lesions) and a specificity of 98% (98 of 100 lesions) for differentiating benign from malignant masses. CONCLUSION: Precontrast attenuation of less than 0 HU supercedes the washout profile in the evaluation of an individual adrenal mass. Noncalcified, nonhemorrhagic adrenal lesions with precontrast attenuation of more than 43 HU should be considered suspicious for malignancy.

Adrenal Gland Diseases↗
PubMed2005

Computer-aided detection for virtual colonoscopy.

Colon cancer is one of the leading causes of cancer deaths in the developed countries. Most colon cancers can be prevented if precursor colon polyps are detected and removed. Virtual colonoscopy, or CT colonography, has shown promise to be the future screening tool for polyp detection, with a number of studies performed at academic institutions showing high sensitivity and specificity. Two main factors limiting CT colonography in general use are its excessive interpretation time and the variable sensitivity among readers. This article discusses the potential of computer-aided detection to address these problems. We also review the current state of research in this field and the future roles and challenges of CAD for CT colonography.

Algorithms↗
PubMed2005

Multi-detector row CT in evaluation of 94 living renal donors by readers with varied experience.

PURPOSE: To retrospectively assess the accuracy of four-section multi-detector row computed tomography (CT) in the evaluation of renal transplant donors when scans are read by one of multiple readers with varied levels of expertise, by using surgery as the reference standard. MATERIALS AND METHODS: This retrospective study was approved by the institutional review board and complied with the Health Insurance Portability and Accountability Act. Informed consent was waived. Between October 1999 and March 2003, 94 renal donors (42 men, 52 women; mean age, 44 years) underwent four-section multi-detector row CT. Unenhanced scanning of the abdomen was performed with 5-mm section thickness and table speed of 15 mm per rotation. Next, 135-150 mL of nonionic iodinated (300 mg/mL) contrast material was injected intravenously at a rate of 4-5 mL/sec. Contrast material-enhanced CT was initiated 20-25 seconds, 65-70 seconds, and 10 minutes after start of injection. Arterial phase scanning was performed with 1.25-mm section thickness and 7.5-mm table speed. Venous and excretory phase scanning was performed with 2.5-mm section thickness and 15-mm table speed. Each scan was evaluated independently by one of 11 readers for renal vascular and ureteral anatomic variants. Findings at CT were compared with those at surgery. Sensitivity and specificity (with 95% confidence intervals) and accuracy of CT were calculated on the basis of presence or absence of variant anatomy at surgery. RESULTS: CT depicted 107 of 114 renal arteries confirmed at surgery; seven accessory arteries were missed in six donor kidneys. CT depicted 95 of 98 renal veins confirmed at surgery. Sensitivity and specificity of CT were 66% and 100%, 75% and 100%, and 50% and 100%, and overall accuracy was 94%, 97%, and 99%, for identification of variant anatomy of renal arteries, veins, and ureters, respectively. CONCLUSION: Multi-detector row CT as the sole imaging technique in the preoperative evaluation of living renal donors is accurate even when images are read by multiple readers with varied levels of expertise.

Adult↗
PubMed2005

MRI in detection of hepatocellular carcinoma (HCC).

Hepatocellular carcinoma (HCC) is the commonest malignancy of the liver and is usually due to cirrhosis. Early detection of HCC and the premalignant dysplastic nodules has implications on the management options of tumor ablation, liver resection and transplantation. Magnetic resonance imaging is useful for the detection and characterization of lesions, in the identification of dysplastic nodules and their malignant transformation into HCC.

Carcinoma, Hepatocellular↗