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Biomedical subjects

D S Lu

Publications and source records attributed to D S Lu.

At least 37 records · Page 2Linked to original sources
PubMed1999

Transvaginal saline hysterosonography: characteristics distinguishing malignant and various benign conditions.

OBJECTIVE: The objective of this study is to establish criteria for distinguishing endometrial polyps, submucosal leiomyomas, endometrial hyperplasia, and endometrial carcinoma on saline hysterosonography. MATERIALS AND METHODS: Sixty-three saline hysterosonograms with histologic confirmation were retrospectively analyzed. We found 26 endometrial polyps, 16 submucosal leiomyomas, three endometrial hyperplasias, one abnormal endometrium associated with a sloughed polyp, one pseudopolyp, and three endometrial carcinomas; 15 sonograms revealed no abnormality. In two patients, sonography revealed both polyps and submucosal leiomyomas. The sonographic appearance of these abnormalities was analyzed to define criteria for their diagnosis. RESULTS: Twenty-five of 26 polyps were uniformly echogenic with smooth borders and either had a stalk or formed acute angles with underlying endometrium. Sixteen of 16 submucosal leiomyomas showed heterogeneous echogenicity; however, 13 were sessile and three were pedunculated. Endometrial hyperplasia was manifested by wall thickening in two patients and tiny polypoid excrescences in one patient. In all patients with endometrial carcinoma, the endometrial cavities were poorly distensible despite successful cervical os cannulation. All patients with abnormalities other than endometrial carcinoma had fully distensible uterine cavities. CONCLUSION: Malignant and various benign endometrial conditions may be accurately distinguished on saline hysterosonography. Uniformity of echogenicity distinguished all polyps from submucosal leiomyomas, but the angulation formed with the endometrial wall by the intracavitary mass did not distinguish all polyps from submucosal leiomyomas. Lack of distensibility of the endometrial canal is a potential sign of endometrial carcinoma.

Adult↗
PubMed1999

MR-guided therapy. Applications in the abdomen.

This article provides an overview of current abdominal interventional applications that use MR imaging guidance and monitoring for diagnostic biopsies, tumor ablations and--owing to the development of new pulse sequences--monitoring the ablation process, and aspiration and drainage of fluid collections. These applications are optimal for patients with lesions that can be localized only by MR imaging or for lesions in suboptimal locations such as the dome of the liver.

Abdomen↗
PubMed1998

Assessment of scoliosis correction in relation to flexibility using the fulcrum bending correction index.

STUDY DESIGN: A prospective study on adolescent idiopathic scoliosis to assess a new method of describing frontal plane correction. OBJECTIVE: To assess the difference between using the correction rate and using the new fulcrum bending correction index when describing scoliosis correction. SUMMARY OF BACKGROUND DATA: A description of the outcome of scoliosis surgery based on the correction rate does not take into account the curve's flexibility. METHODS: The fulcrum bending correction index is calculated by dividing the correction rate by the fulcrum flexibility (based on the fulcrum bending radiograph) and is expressed as a percentage. The fulcrum bending correction index was compared with the correction rate in 35 patients with adolescent idiopathic scoliosis undergoing surgical correction. These patients were divided into a stiff and a flexible group based on a fulcrum flexibility of 50% to show the advantage of the fulcrum bending correction index over the correction rate. RESULTS: The difference in correction rate between the flexible (66%) and the stiff group (45%) was significant (P < 0.05). The difference in the fulcrum bending correction index between the flexible (96%) and the stiff group (107%) was not significant (P = 0.2). CONCLUSIONS: The fulcrum bending correction index takes into account the curve flexibility and is therefore better than the correction rate for comparing curve correction and use of instrumentation systems between different series of patients. A fulcrum bending correction index of close to 100% suggests that the instrumentation has taken up all the flexibility revealed by the fulcrum bending radiograph. It is recommended that the fulcrum bending correction index be used in the future as part of the postoperative assessment of frontal plane correction in cases of thoracic scoliosis.

Adolescent↗
PubMed1998

Small peripancreatic veins: improved assessment in pancreatic cancer patients using thin-section pancreatic phase helical CT.

OBJECTIVE: Recent studies have shown evaluation of the small peripancreatic veins to have potential in improving pancreatic cancer staging. This study was performed to determine the effectiveness of thin-section pancreatic phase helical CT images in visualizing these veins. MATERIALS AND METHODS: Seventy-two patients (30 with pancreatic adenocarcinoma and 42 with no pancreatic disease) underwent dual-phase helical CT with thin-section pancreatic phase acquisition (40-70 sec after i.v. contrast initiation at 3 ml/sec) and hepatic phase acquisition (70-100 sec). Visualization (with diameter measurement) or nonvisualization of the posterior superior pancreaticoduodenal vein (PSPDV), anterior superior pancreaticoduodenal vein (ASPDV), and gastrocolic trunk was recorded for both acquisitions. We also correlated surgical tumor resectability with the status of the small peripancreatic veins. RESULTS: Visualization of peripancreatic veins was significantly better on pancreatic phase images than on hepatic phase images for both healthy individuals (PSPDV, 88% of the veins visualized on the pancreatic phase images versus 50% on the hepatic phase images; ASPDV, 93% on the pancreatic phase images versus 48% on the hepatic phase images; gastrocolic trunk, 98% on the pancreatic phase images versus 76% on the hepatic phase images) and for pancreatic cancer patients (PSPDV, 97% on the pancreatic phase images versus 57% on the hepatic phase images; ASPDV, 77% on the pancreatic phase images versus 43% on the hepatic phase images) (p < .05). The exception was the gastrocolic trunk in cancer patients (83% on the pancreatic phase images versus 77% on the hepatic phase images) (p > .05). In pancreatic cancer patients, 11 dilated peripancreatic veins were identified on the pancreatic phase images compared with six on the hepatic phase images. However, only one of the 11 dilated peripancreatic veins was in a patient with surgically resectable disease. CONCLUSION: In a dual-phase helical CT protocol, thin-section pancreatic phase images provided visualization of the small peripancreatic veins that was superior to hepatic phase images, providing further support for the use of this protocol in pancreatic cancer evaluation.

Adenocarcinoma↗
PubMed1997

Biopsy of hepatic dome lesions: semi-real-time coronal MR guidance technique.

OBJECTIVE: MR imaging, with its coronal imaging capability, may be ideally suited for biopsies of hepatic dome lesions. We are reporting on the successful semi-real-time biopsy of such lesions using a 0.2-T open-configuration MR scanner in five patients. CONCLUSION: MR guidance holds promise for facilitating biopsies of hepatic dome masses.

Adult↗
PubMed1997

Local staging of pancreatic cancer: criteria for unresectability of major vessels as revealed by pancreatic-phase, thin-section helical CT.

OBJECTIVE: This study was conducted to determine the criteria for unresectability of major peripancreatic vessels in patients with pancreatic carcinoma as revealed by optimally enhanced, pancreatic-phase thin-section helical CT. SUBJECTS AND METHODS: Twenty-five patients with pancreatic adenocarcinoma who underwent local dissection during curative or palliative surgery also underwent preoperative pancreatic-phase thin-section helical CT (40- to 70-sec delay, 2.5- to 3-mm collimation). Tumor involvement of the portal and superior mesenteric veins and the celiac, hepatic, and superior mesenteric arteries was prospectively graded on a 0-4 scale based on circumferential contiguity of tumor to vessel. Subsequent surgical results were then correlated with the CT grades. RESULTS: At surgery, definitive evaluation was possible for 80 vessels. Forty-eight of 48 vessels graded 0 and three of three vessels graded 1 were resectable. Four of seven vessels graded 2, seven of eight vessels graded 3, and 14 of 14 vessels graded 4 were unresectable. A threshold of between grades 2 and 3, which corresponded to tumor involvement of one-half circumference of the vessel, yielded the lowest number of false-negatives and an acceptable number of false-positives for unresectability. Such a threshold would have yielded a sensitivity of 84%, a specificity of 98%, a positive predictive value of 95%, and a negative predictive value of 93% for unresectability of the vessels studied. CONCLUSION: A grading system for tumor involvement of the major vessels in patients with pancreatic adenocarcinoma can be based on the degree of circumferential contiguity of tumor to vessel. Involvement of vessel to tumor that exceeds one-half circumference of the vessel is highly specific for unresectable tumor.

Adenocarcinoma↗
PubMed1997

Hepatic lesion characterization in cirrhosis: significance of arterial hypervascularity on dual-phase helical CT.

OBJECTIVE: Our goal was to evaluate the diagnostic significance of the presence and pattern of arterial hypervascularity in lesions detected on dual-phase helical CT in cirrhotic patients. MATERIALS AND METHODS: Fifty-eight lesions greater than 1 cm in size were prospectively identified in 26 patients with end-stage liver disease who had undergone dual-phase helical CT for preoperative liver transplantation evaluation. All 26 patients had diagnoses proven by histologic evaluation or by clinical criteria. All arterial phase scans were retrospectively reviewed and lesions were categorized for the presence and pattern of arterial hypervascularity. Radiologic findings were correlated with histopathologic data. RESULTS: Thirty-seven of the 58 lesions had hypervascular components on arterial phase scans. All 37 of these lesions were found to represent hepatocellular carcinoma (HCC) (positive predictive value, 100%). Of the 21 remaining hypovascular lesions, 17 were HCC and four were benign (positive predictive value, 81%). Of the nine patients in whom all lesions were hypovascular, six had HCC (positive predictive value, 66%). The value of the presence of arterial hypervascularity for diagnosing HCC was statistically significant (p < .05). However, the presence or absence of arterial hypervascularity and the specific enhancement pattern revealed by helical CT did not correlate with histologic grading. CONCLUSION: The presence of hypervascularity in hepatic masses found in cirrhotic patients is highly predictive of malignancy.

Adult↗
PubMed1996

Helical computed tomography for abdominal imaging.

Significant technologic advances have taken place in computed tomography (CT). Current-generation conventional CT scanners are able to image a slice of tissue in as little as 2 to 3 seconds and can acquire several consecutive images. Although it is a substantial improvement from the CT of 5 years ago, there remain practical limits to the utility of conventional CT imaging within the abdomen. Recently, a new type of CT gantry design ("slip-ring") and faster computers have contributed to the development of a new generation of CT scanners, the "helical" or "spiral" CT scanners.

Humans↗
PubMed1996

Solid and papillary neoplasm of the pancreas: radiological-pathological study of five cases and review of the literature.

OBJECTIVE: To present five cases of the rare solid and papillary neoplasm of the pancreas with pathological correlation and review of the literature. PATIENTS AND METHODS: Five patients (all female, two Caucasian, one Philipino and two Hispanic) with solid and papillary neoplasm of the pancreas were reviewed. Four patients were under 28 years of age but one patient was 44 years old at presentation. Review consisted of imaging (CT in all and ultrasound in three patients), gross pathological and histological appearance (5/5 specimens), immunohistochemistry (4/5 specimens) and clinical follow-up. RESULTS: All five tumours were successfully resected without recurrence. All tumours were well-encapsulated but showed a wide spectrum of solid peripheral tumour with central cystic degeneration on imaging. Cystic spaces corresponded to haemorrhagic necrosis on histology. One tumour showed rim calcification. Immunohistological staining showed variable expression of both exocrine and endocrine markers. CONCLUSION: Although non-specific, solid and papillary neoplasm of the pancreas is characteristically a benign, well-encapsulated solid tumor with varying degree of central necrosis in young female patients. No racial predilection was demonstrated in this small series.

Adolescent↗
PubMed1996

Two-phase helical CT for pancreatic tumors: pancreatic versus hepatic phase enhancement of tumor, pancreas, and vascular structures.

PURPOSE: To quantitatively evaluate and validate a two-phase helical computed tomographic (CT) protocol for evaluation of pancreatic tumors. MATERIALS AND METHODS: Twenty-seven patients with pathologically proved pancreatic adenocarcinomas prospectively underwent two-phase CT examination with helical acquisition during the pancreatic phase (40-70 seconds after infusion of intravenous contrast material at 3 mL/sec) and the hepatic phase (70-100 seconds after infusion). Mean CT attenuation values of tumor, bordering pancreas, and all major peripancreatic vessels were obtained for both time intervals. RESULTS: Mean tumor-pancreas contrast was significantly greater during the pancreatic phase (67 HU +/- 19) than the hepatic phase (39 HU +/- 16) (P < .001) This was the result of both greater enhancement of normal pancreas and lower tumor enhancement during the pancreatic phase. Opacification of all vascular structures, including the portal vein, was also greater during the pancreatic phase (P < .001). CONCLUSION: Two-phase helical CT with pancreatic phase acquisition provides statistically significantly better pancreatic, arterial, and portal venous enhancement than that of hepatic phase imaging, with improved tumor-pancreas contrast.

Adenocarcinoma↗
PubMed1996

Preoperative staging of cancer of the pancreas: value of MR angiography versus conventional angiography in detecting portal venous invasion.

OBJECTIVE: The purpose of this study was to compare contrast-enhanced MR angiography with conventional catheter angiography for detecting portal venous invasion in the preoperative staging of pancreatic cancer, using the surgical confirmation of vascular involvement as the standard of truth. SUBJECTS AND METHODS: MR and conventional angiography were performed in 20 patients with pancreatic carcinoma, with surgical confirmation in all cases. MR angiography was performed at 1.5 T, with coronal (2.9 mm) and axial (6.0 mm) contrast-enhanced breath-hold two-dimensional time-of-flight imaging. Data from each imaging technique were collected prospectively and analyzed in a blinded fashion by expert vascular radiologists. Vascular involvement in each patient and in each vessel (main portal vein, confluence, splenic vein, and superior mesenteric vein) determined whether the tumor was resectable (normal, abutment) or nonresectable (encased, occluded). Surgical confirmation of the vascular involvement of the portal venous structures was used as the standard of truth in all patients. RESULTS: Among the 20 patients, 11 tumors were surgically resectable and seven were nonresectable with performance of a palliative bypass. MR angiography and conventional angiography had an overall concordance in 65% of patients (13/20; seven resectable, four nonresectable, two false-negatives) on the basis of the vascular status in each patient of the portal venous structures and in 84% (47/56) of the individual vessels surgically confirmed. MR angiography correctly identified 11 of 11 resectable patients and five of nine nonresectable patients, with four false-negative cases. Conventional angiography correctly identified seven of 11 resectable patients and six of nine nonresectable patients, with three false-negative cases and four false-positive cases. CONCLUSION: The lack of false-positives by MR angiography suggests that MR imaging may provide a noninvasive screen for nonresectability on the basis of vascular involvement, with no patients with potentially resectable tumors being denied surgery by MR angiography in this cohort. However, the presence of false-negatives using MR angiography indicates the procedure would still not fully eliminate unnecessary laparotomies.

Aged↗
PubMed1996

Congenital or idiopathic hepatic vascular malformations: CT findings.

OBJECTIVE: Five CT studies in three patients with congenital or idiopathic hepatic vascular malformations were reviewed. CONCLUSION: Consistent findings included direct visualization of the abnormal vessels, hepatomegaly, and changes of fibrosis. Dual-phase helical CT in two patients also revealed arteriovenous shunting. One patient had growth of the malformation over 7 years.

Adult↗
PubMed1994

Percutaneous internal ureteral stent placement: review of technical issues and solutions in 50 consecutive cases.

Fifty consecutive percutaneous ureteral stent placements in 40 patients over 2 1/2 years were reviewed. Thirty-seven of 50 cases were performed following failed retrograde stenting. Antegrade stenting failed in 2/37 (5%) cases of malignant obstruction, and 4/13 (31%) cases of benign ureteral disease. Causes of failure and common technical problems included poor angulation of the percutaneous track, tortuous dilated ureters, tight obstructions, wedging of stent assembly components due to high resistance, and difficulty in positioning of the proximal pigtail. Helpful technical modifications included mid-pole rather than lower pole calyceal access, urinary decompression prior to stenting, and the routine use of a peel-away sheath (success rate 23/24 placements with sheath vs 21/26 without sheath). Stent patency rates were 95% at 3 months and 54% at 6 months. With attention to technique and appropriate modifications, success rate of percutaneous stenting remained high in this series despite the large number of cases referred after retrograde stenting had failed.

Adolescent↗
PubMed1994

Failed metallic biliary stents: causes and management of delayed complications.

OBJECTIVE: To describe the incidence, management and long-term outcome of metal stent failure in patients with malignant biliary obstruction. SUBJECTS AND METHODS: Sixty-nine patients received a total of 93 metallic biliary stents for relief of malignant biliary obstruction. Twenty-nine patients had hilar tumours; 40 had common bile duct tumours. RESULTS: Ten of 69 patients (14%) presented with stent occlusion at a mean interval of 4 months after stent insertion. Five of 29 patients (17%) with hilar lesions and five of 40 patients (12%) with common bile duct lesions had stent occlusion. Occlusion was due to tumour overgrowth in eight patients and to occlusion by debris in two. The eight patients with tumour overgrowth were treated with internal/external catheters (5 patients), no therapy (2 patients), and further metal stents (1 patient). These eight patients with tumour overgrowth had a limited lifespan after tumour overgrowth occurred with a mean survival of 2.6 months. The two patients with occlusion due to debris were treated by sweeping the stent with a balloon catheter and these patients survived 26 and 27 months, respectively. CONCLUSION: Adequate peripheral purchase in the biliary tree and overstenting are necessary to prevent tumour overgrowth when stenting hilar lesions. The development of stent occlusion due to tumour overgrowth heralds a limited survival and internal/external catheters are preferred over further metal stents for palliation.

Adult↗
PubMed1994

T2-weighted MR imaging of the upper part of the abdomen: should fat suppression be used routinely?

OBJECTIVE: Fat suppression has shown promise in improving the quality of T2-weighted spin-echo MR images of the upper part of the abdomen. The purpose of this study was to determine whether fat-suppressed images should be routinely used in lieu of conventional images. Accordingly, we prospectively compared the two techniques in a series of patients with both normal and abnormal findings in the upper part of the abdomen. MATERIALS AND METHODS: Conventional and fat-suppressed T2-weighted spin-echo images (3000/80,160 [TR/TE]) were obtained in 45 consecutive patients referred for MR imaging of the upper part of the abdomen. Thirty-three patients had abnormal findings, and 22 of those 33 patients had histologic or follow-up confirmation of the diagnosis (14 with metastasis, one with hepatoma, four with hemangiomas, and three with cysts). Signal intensities (hepatic lesions, liver, spleen) and noise were measured to calculate signal-to-noise ratios and contrast-to-noise ratios. Qualitative comparison (liver, hepatic lesions, porta hepatis, spleen, pancreas, bowel, kidneys, adrenal glands, noise), evaluation of the number of hepatic lesions, and characterization of hepatic lesions were done by independent observers. RESULTS: Compared with conventional images, fat-suppressed images had higher signal-to-noise ratios (lesions, liver, spleen) and contrast-to-noise ratios (lesion-liver and spleen-liver) (p < .005). In qualitative comparison, three of three radiologists preferred fat-suppressed over conventional images for depiction of hepatic lesions and all upper abdominal organs except the liver, for which no clear preference was shown for either technique. Detection rates for hepatic lesions were similar with both types of images (observer 1: 112 lesions on fat-suppressed vs 118 on conventional images, observer 2: 142 vs 135), as was the characterization of hepatic lesions (91% accuracy on fat-suppressed images and 84% accuracy on conventional images, for 22 proved lesions and two observers). CONCLUSION: Fat-suppressed T2-weighted spin-echo MR images were better than non-fat-suppressed images for evaluation of the upper part of the abdomen. These results suggest that fat suppression should be routinely used in T2-weighted MR imaging of the upper part of the abdomen.

Abdomen↗
PubMed1994

Gallstones in critically ill patients with acute calculous cholecystitis treated by percutaneous cholecystostomy: nonsurgical therapeutic options.

OBJECTIVE: Patients with acute calculous cholecystitis require removal of gallstones (generally cholecystectomy), as acute cholecystitis is likely to recur if gallstones are left in situ. The purpose of this study was to assess the role of nonsurgical techniques for treating gallstones in critically ill patients with acute calculous cholecystitis managed by percutaneous cholecystostomy. MATERIALS AND METHODS: Twenty-six critically ill patients with complex medical and surgical problems who were in intensive care units underwent emergent percutaneous cholecystostomy for acute calculous cholecystitis. Seven of the 26 patients subsequently died of multiple organ failure. Curative gallstone therapies were tried in the surviving 19 patients, seven of whom underwent elective surgical cholecystectomy. Nonsurgical management was attempted in 12 of 19 patients, including six with terminal disease who were treated with long-term gallbladder drainage, three who were treated with methyl tert-butyl ether for stone dissolution, two who had percutaneous cholecystolithotomy, and one who had a gallbladder stone that had passed into the common bile duct and was retrieved endoscopically. RESULTS: Long-term gallbladder drainage was successful in all six patients with terminal disease in whom it was attempted; they experienced no further episodes of cholecystitis. In four of the other six patients treated with nonsurgical therapies (percutaneous cholecystolithotomy, stone dissolution with methyl tert-butyl ether, and endoscopic removal), gallstones were successfully removed and no further therapy was required. Percutaneous therapies failed in two patients, who then had cholecystectomy. CONCLUSION: Nonsurgical gallstone therapies should be attempted in high-risk patients with acute calculous cholecystitis. Some patients may benefit from long-term catheter drainage of the gallbladder.

Acute Disease↗