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Biomedical subjects

R B Jeffrey

Publications and source records attributed to R B Jeffrey.

At least 19 recordsLinked to original sources
PubMed2001

Tissue harmonic imaging techniques: physical principles and clinical applications.

Tissue harmonic imaging (THI) is a new gray-scale sonographic technique that improves image clarity. Harmonics form within the insonated tissue as a consequence of nonlinear sound propagation. Imaging with endogenously formed harmonics means that the distorting layer of the body wall is traversed only once by the harmonic beam--during echo reception. Both image contrast and lateral resolution are improved in harmonic mode compared with conventional (fundamental mode) sonography. This article summarizes the physics and various implementations of harmonic imaging mode, and reviews the clinical applications that have emerged to date.

Acoustics↗
PubMed2001

Imaging the patient with right upper quadrant pain.

A variety of high-resolution imaging techniques are currently available for the evaluation of patients with RUQ pain. In these patients, an imaging approach that is based on identifying the presence of certain clinical signs and symptoms can aid in choosing the appropriate imaging modality and establishing the diagnosis. For patients presenting with a positive Murphy sign, sonography and biliary scintigraphy are the most useful initial imaging techniques. In patients with fever and a negative Murphy sign, a combination of sonography and contrast-enhanced CT can establish the diagnosis in most cases. And finally, in patients without fever or a positive Murphy sign, CT and MR are appropriate first-line imaging techniques.

Abdomen, Acute↗
PubMed2001

Intraoperative ultrasonography for localization of recurrent thyroid cancer.

Advances in measurement of thyroglobulin (Tg) and in imaging techniques including high resolution ultrasound, magnetic resonance imaging (MRI), computed tomography (CT), and positron emission tomography (PET) scan have increased our ability to detect thyroid cancer recurrences at an earlier stage. (1,2) After thyroidectomy, patients are often treated with radioiodine, but the recurrent cancers may not image with radioiodine. In these instances, the only definitive treatment is surgical resection. Reoperative neck surgery can be challenging, especially when trying to find a small cancer nodule within the central neck that contains dense fibrotic scar tissue. Herein we describe the use of intraoperative ultrasonography to identify the location of recurrent thyroid cancer. This technique can aid in tumor localization and may help to avoid complications such as recurrent nerve injury.

Carcinoma, Papillary↗
PubMed2001

A statistical 3-D pattern processing method for computer-aided detection of polyps in CT colonography.

Adenomatous polyps in the colon are believed to be the precursor to colorectal carcinoma, the second leading cause of cancer deaths in United States. In this paper, we propose a new method for computer-aided detection of polyps in computed tomography (CT) colonography (virtual colonoscopy), a technique in which polyps are imaged along the wall of the air-inflated, cleansed colon with X-ray CT. Initial work with computer aided detection has shown high sensitivity, but at a cost of too many false positives. We present a statistical approach that uses support vector machines to distinguish the differentiating characteristics of polyps and healthy tissue, and uses this information for the classification of the new cases. One of the main contributions of the paper is the new three-dimensional pattern processing approach, called random orthogonal shape sections method, which combines the information from many random images to generate reliable signatures of shape. The input to the proposed system is a collection of volume data from candidate polyps obtained by a high-sensitivity, low-specificity system that we developed previously. The results of our ten-fold cross-validation experiments show that, on the average, the system increases the specificity from 0.19 (0.35) to 0.69 (0.74) at a sensitivity level of 1.0 (0.95).

Adult↗
PubMed2001

Parathyroid crisis in a 20 year old--an unusual cause of hypercalcaemic crisis.

Since the advent of automated serum analysis, patients with primary hyperparathyroidism (PHPT) are often asymptomatic at presentation or have mild symptoms attributable to the disease. Parathyroid crisis is a rare and potentially fatal complication of PHPT in which patients develop severe hypercalcaemia with signs and symptoms of multiple organ dysfunction. A case of parathyroid crisis in a 20 year old man who presented with brown tumours and renal stones is described.

Adult↗
PubMed2001

Impact of multidetector CT hepatic arteriography on the planning of chemoembolization treatment of hepatocellular carcinoma.

OBJECTIVES: We examined the impact of the increased sensitivity for hypervascular masses of multidetector CT hepatic arteriography on treatment decisions involving selective chemoembolization of hepatocellular carcinomas. SUBJECTS AND METHODS: Thirty patients were referred for chemoembolization of unresectable hepatocellular carcinoma. Initial selective chemoembolization plans were formulated on the basis of diagnostic biphasic CT or MR imaging. Ultrafast CT hepatic arteriography was performed using a multidetector CT scanner and selective contrast material injection into the hepatic artery. The entire liver was scanned in a single breath-hold of approximately 20 sec with a slice thickness of 1 mm. Lesions and their arterial supplies were identified, and these data were immediately used to formulate a final plan for chemoembolization. RESULTS: Hypervascular masses were detected in 29 patients. In 16 (53%) of the patients, preprocedural CT or MR imaging underestimated the number of lesions. In nine (30%) of these 16 patients, the additional lesions were detected only on CT hepatic arteriography, not on conventional angiography. CT hepatic arteriography findings had a major impact on planning the way in which chemoembolization treatment was performed. In three of the nine patients, the previously undetected lesions were treated with additional superselective chemoembolization. In the other six patients, chemoembolization was performed less selectively than originally planned. CONCLUSION: Primarily because of the high sensitivity of multidetector CT hepatic arteriography in revealing small and multifocal hepatomas, findings of this modality frequently alter treatment plans involving selective administration of chemoembolic material.

Adult↗
PubMed2001

Preoperative duplex ultrasonography evaluation for deep venous thrombosis in revision hip arthroplasty patients.

In a prospective consecutive series, 53 revision hip arthroplasties were performed in 51 patients. Pre- and postoperative Duplex ultrasonography examinations were reviewed by an independent, experienced radiologist. Three of 51 patients (53 procedures) had evidence of chronic deep venous thrombosis (DVT) or other venous abnormality preoperatively, yielding an incidence of 5.6%. One (1.9%) patient developed an acute DVT postoperatively despite pharmacological and mechanical preventative measures. These results indicate the use of preoperative ultrasonography as a screening tool prior to revision hip arthroplasty is not warranted based on the low incidence of acute or chronic DVT detected preoperatively. Long-term anticoagulation, when necessary, can be based on the findings of a postoperative scan.

Adult↗
PubMed2001

Ultrasonographically guided thyroid biopsy: a review with emphasis on technique.

We describe our technique for ultrasonographically guided fine-needle aspiration biopsy of the thyroid that achieves a high rate of diagnostic specimens. Indications for ultrasonographically guided fine-needle aspiration biopsy included a difficult-to-palpate thyroid nodule and previously unsuccessful palpation-guided fine-needle aspiration. Ultrasonographically guided fine-needle aspiration biopsy was performed on 316 thyroid nodules in 306 patients. Adequate cytologic specimens were obtained in 97.2% of the nodules in which biopsy was performed, with a 2.8% rate of inadequate cellularity. Two helpful aspects of this technique that were thought to improve the overall diagnostic yield were the use of color and power Doppler "vascular mapping" of the nodule just before biopsy and on-site cytologic control.

Biopsy, Needle↗
PubMed2000

Aortic aneurysmal disease: assessment of stent-graft treatment-CT versus conventional angiography.

PURPOSE: To compare computed tomographic (CT) angiography and conventional angiography for determining the success of endoluminal stent-graft treatment of aortic aneurysms. MATERIALS AND METHODS: Forty patients underwent conventional angiography and CT angiography following treatment of aortoiliac aneurysms with endoluminal stent-grafts. Six additional sets of conventional angiographic-CT angiographic examinations were performed in five patients after placement of additional stent-grafts or coil embolization to treat perigraft leakage. Three faculty CT radiologists who were blinded to patient clinical data and outcome independently interpreted the CT angiograms, and three faculty angiographers, who were not involved in the stent-graft deployment, interpreted the conventional angiograms. Images were assessed for the presence of postdeployment complications. A reference standard was developed by experienced radiologists using all available images and clinical data. Sensitivities, specificities, and kappa values were calculated. RESULTS: Perigraft leakage was the most commonly identified complication. Twenty perigraft leaks were detected in the results of 46 examinations. Sensitivities and specificities for detecting perigraft leakage were 63% and 77% for conventional angiography and 92% and 90% for CT angiography, respectively. The kappa value was 0. 41 for conventional angiography and 0.81 for CT angiography. CONCLUSION: CT angiography is the preferred method for establishing the presence of perigraft leakage following treatment of aortoiliac aneurysms with stent-grafts.

Adult↗
PubMed2000

Focal liver lesions: pattern-based classification scheme for enhancement at arterial phase CT.

PURPOSE: To present our early experience with a classification scheme for categorizing focal liver lesions on the basis of the enhancement patterns that they exhibit in the arterial phase of computed tomography (CT) and to determine whether particular enhancement patterns suggest particular diagnoses. MATERIALS AND METHODS: The authors reviewed arterial phase CT images in 100 consecutive patients with focal liver lesions, excluding simple cysts. The enhancement pattern of the dominant or representative lesion in each patient was classified into one of five categories-homogeneous, abnormal internal vessels or variegated, peripheral puddles, complete ring, or incomplete ring-by three radiologists blinded to the proved diagnosis. Lesions without enhancement were recorded separately. Agreement was reached by consensus in all cases. Standards of reference included findings at histologic examination, correlative imaging, or clinical and imaging follow-up. RESULTS: Ninety-two percent of the 100 lesions demonstrated arterial phase enhancement. Patterns associated with positive predictive values of 82% or greater and specificity of 80% or greater included abnormal internal vessels or variegated (hepatocellular carcinoma), peripheral puddles (hemangioma), and complete ring (metastasis). CONCLUSION: The appearance of hepatic lesions in the arterial phase of enhancement has potential use in the determination of specific diagnoses. The classification scheme used in this study may be a useful tool for the interpretation of arterial phase CT studies.

Adult↗
PubMed2000

Automated polyp detector for CT colonography: feasibility study.

An abdominal computed tomographic scan was modified by inserting 10 simulated colonic polyps with use of methods that closely mimic the attenuation, noise, and polyp-colon wall interface of naturally occurring polyps. A shape-based polyp detector successfully located six of the 10 polyps. When settings that enhanced the edge profile of polyps were chosen, eight of 10 polyps were detected. There were no false-positive detections. Shape analysis is technically feasible and is a promising approach to automated polyp detection.

Colon↗
PubMed2000

Thickened submucosal layer: a sonographic sign of acute gastrointestinal abnormality representing submucosal edema or hemorrhage. 2000 ARRS Executive Council Award II. American Roentgen Ray Society.

OBJECTIVE: We correlated the sonographic appearance of bowel wall thickening with the acuity of the underlying disease process. SUBJECTS AND METHODS: Sonograms of thickened bowel walls were reviewed in 37 patients with proven gastrointestinal abnormalities. Sonographic findings were correlated with clinical presentation, endoscopy, histology, laboratory data, barium studies, and CT. RESULTS: Twenty-eight patients presented acutely, and nine patients had chronic or subacute disease processes. Two of the 28 patients had concurrent acute and chronic processes. In 27 of 28 patients with acute processes, the abnormal bowel segments were characterized by an echogenic submucosal layer thicker than 2.5 mm. In contrast, nine patients with chronic or subacute processes had relatively uniform hypoechoic thickening of the bowel wall with loss of visualization of a discrete echogenic submucosal layer. CT was available for comparison in 30 of 37 patients. Of the 28 patients with acute abnormalities, the thickened echogenic submucosal layer on sonography corresponded to either low-attenuation submucosal edema (n = 25) or acute submucosal hemorrhage (n = 3). CONCLUSION: The finding of a thickened submucosal layer suggests an acute disease process of the bowel and corresponds to either submucosal edema or hemorrhage.

Acute Disease↗
PubMed1999

Parathyroid localization with high-resolution ultrasound and technetium Tc 99m sestamibi.

HYPOTHESIS: High-resolution ultrasound and technetium Tc 99m sestamibi scanning can be used for preoperative localization of abnormal parathyroid glands in patients with hyperparathyroidism. DESIGN: Ultrasound and sestamibi scanning were performed in patients undergoing neck exploration for hyperparathyroidism. If the 2 scans agreed in identifying a single adenoma, and surgery confirmed the location of a single adenoma and an ipsilateral normal gland, a unilateral exploration was performed. SETTING: University tertiary care center. PATIENTS: Sixty-one consecutive patients undergoing surgery for hyperparathyroidism from September 1, 1994, through September 30, 1997. INTERVENTIONS: High-resolution ultrasound was performed in 59 patients and sestamibi scanning in 58 patients; all patients underwent neck exploration by a single surgeon. MAIN OUTCOME MEASURES: The results of preoperative ultrasound and sestamibi scanning were compared with operative and histological findings. RESULTS: All patients were cured of hypercalcemia. Specificity of ultrasound and sestamibi scanning was 98% and 99%, respectively; however, their sensitivity was only 57% and 54%, respectively. Both imaging modalities had lower sensitivities in the setting of multigland disease. If both imaging studies were considered as a single test, sensitivity for imaging in patients with primary hyperparathyroidism reached 78%. Our localization protocol allowed a unilateral approach in 43% of patients (23 of 53). CONCLUSIONS: These results confirm the value of preoperative localization in patients with hyperparathyroidism. A unilateral approach can be used with a high degree of success in cases when ultrasound and sestamibi scanning agree in the identification of a single adenoma confirmed by surgical exploration with the identification of a normal ipsilateral gland.

Adenoma↗
PubMed1999

Power Doppler imaging of acute renal transplant rejection.

PURPOSE: We evaluated the usefulness of power Doppler imaging (PDI) in diagnosing acute renal-transplant rejection. METHODS: Twenty-eight patients underwent 33 renal-transplant biopsies for suspected acute rejection. Patterns of renal parenchymal vascularity revealed by PDI in patients with abnormal biopsy results were compared with patterns in a group who had normal biopsy results. PDI examinations were reviewed retrospectively by 2 independent radiologists who had no knowledge of the biopsy results. A PDI diagnosis of acute rejection required marked vascular pruning in both the cortex and medulla. PDI results then were compared with transplant-biopsy results. RESULTS: The sensitivity and specificity of PDI for diagnosing acute renal-transplant rejection were 40% and 100%, respectively. None of the patients with negative biopsy results had PDI abnormalities. The negative predictive value of PDI was 33%, and the positive predictive value was 100%. CONCLUSIONS: In our study, an abnormal sonogram was highly predictive of acute transplant rejection. However, a normal sonogram did not exclude the possibility of rejection.

Acute Disease↗
PubMed1999

The acute abdomen: current CT imaging techniques.

Currently, CT plays a pivotal role in the evaluation of the patient with an acute abdomen. Several competing techniques have been described and investigated. Each appears to possess advantages and disadvantages which will be examined. Each imaging center needs to modify these protocols to satisfy local scanner availability, patient demographics, radiologic expertise, and economic considerations.

Abdomen, Acute↗
PubMed1999

Treatment and stabilization of complex wounds involving the pelvic bone, groin, and femur with the inferiorly based rectus abdominis musculocutaneous flap and the use of power color Doppler imaging in preoperative evaluation.

The authors present case reports demonstrating the trilevel utility of the inferiorly based rectus abdominis musculocutaneous flap in the closure of complex wounds involving the pelvis, groin, and femur that had failed previously or were not amenable to traditional closure techniques. The use of the rectus abdominis flap was especially advantageous for achieving infection eradication and large dead space closure. Additionally they present the emerging technique of power color Doppler imaging as a valuable tool in preoperative flap planning. This technique is particularly useful in evaluating the candidacy for rectus abdominis musculocutaneous flap placement of patients with a prior history of abdominal surgeries, trauma, infection, irradiation, or other conditions that might compromise the patency of the deep inferior epigastric vessels.

Adult↗