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Biomedical subjects

S B Gay

Publications and source records attributed to S B Gay.

At least 37 records · Page 2Linked to original sources
PubMed1994

Evaluation of a breast biopsy phantom for learning freehand ultrasound-guided biopsy of the liver.

RATIONALE AND OBJECTIVES: We evaluated whether a breast biopsy phantom device would aid in the development of skills in freehand ultrasound liver biopsy. METHODS: Three radiologists who were inexperienced in freehand biopsy of the liver were observed. Each radiologist was timed and scored during attempts to biopsy lesions created in a beef liver. The time required for biopsy and the success of each pass was recorded. A commercially available breast biopsy phantom was then used by each of these radiologists during two 20-min practice sessions. Posttraining testing on the beef liver was performed in the same manner as pretraining testing. RESULTS: Freehand biopsy practice using the breast biopsy phantom resulted in a reduction in the mean time required for biopsy from 32 to 17 sec. Each of the three subjects reduced the mean time required for successful biopsy after training using the breast biopsy phantom. The total number of lesions missed was reduced from 14 of 43 to 0 of 45. CONCLUSION: Practice using the ultrasound breast biopsy phantom improves performance in freehand ultrasound biopsy of the liver.

Animals↗
PubMed1994

MR imaging of the liver: breath-hold T1-weighted MP-GRE compared with conventional T2-weighted SE imaging--lesion detection, localization, and characterization.

PURPOSE: To compare breath-hold T1-weighted magnetization-prepared gradient-echo (MP-GRE) imaging with conventional T2-weighted spin-echo (SE) imaging in evaluation of focal liver disease. MATERIALS AND METHODS: Images of 68 patients evaluated for focal liver disease were reviewed. Five sets of images were analyzed: axial, sagittal, and coronal breath-hold T1-weighted MP-GRE images, axial T2-weighted SE images, and a compilation of axial, sagittal, and coronal (three-plane) T1-weighted MP-GRE images. Lesion signal intensity (SI) and signal difference-to-noise (SD/N) ratios were calculated. RESULTS: Lesions were detected, localized, and characterize more accurately (P < .05-.001) and with greater confidence on three-plane T1-weighted MP-GRE images than on almost all single-plane images. Mean SI ratios of nonsolid and solid lesions on MP-GRE and SE images were significantly different at all lesion sizes; mean SD/N ratio was significantly different only for large lesions. CONCLUSION: Lesion detection, localization, and characterization can be accurately and confidently performed with three-plane T1-weighted MP-GRE breath-hold imaging, potentially obviating conventional T2-weighted SE imaging.

Artifacts↗
PubMed1994

Breath-holding capability of adults. Implications for spiral computed tomography, fast-acquisition magnetic resonance imaging, and angiography.

PURPOSE: The breath-holding capabilities of various groups of individuals were evaluated to develop protocols so that patients undergoing spiral computed tomography (CT), digital angiography, and breath-hold magnetic resonance imaging (MRI) can be studied successfully. METHODS: Twenty-five outpatients and 25 inpatients (all adults) were studied before undergoing body CT. Each subject was asked to hold his or her breath for as long as possible. Then each patient was asked to perform as many repetitive 12-second breath holds as possible. These data were correlated with demographic and historical information. RESULTS: The maximum breath-hold time for inpatients and those outpatients who were heavy smokers or had chronic obstructive pulmonary disease (COPD) or congestive heart failure (CHF) was 18 to 32 seconds (95% confidence interval) with a mean of 25 seconds. For all other outpatients, breath-hold time was 38 to 56 seconds (mean = 45 seconds). The 95% confidence interval for the number of 12-second breath holds for these two groups was 4 to 6 breath holds (mean = 4.9) and 6 to 7 breath holds (mean = 6.6), respectively. One inpatient could not hold his breath at all and three others were only able to hold their breath once for short periods. The sex and age of the patient had no significant effect on breath-holding performance. CONCLUSIONS: Breath-holding protocols must account for the diminished capabilities of most inpatients, and outpatients who are heavy smokers or have COPD or CHF. Most outpatients who are not heavy smokers or without COPD or CHF can achieve a single breath hold of 38 seconds, or up to six 12-second breath holds.

Angiography, Digital Subtraction↗
PubMed1993

Multiplanar reconstruction in magnetic resonance evaluation of the knee. Comparison with film magnetic resonance interpretation.

RATIONALE AND OBJECTIVES: At many institutions, three-dimensional magnetic resonance imaging (MRI) is routinely used for examination of the knee. Multiplanar reconstruction (MPR) is a method of displaying three-dimensional datasets. The authors assessed the usefulness of MPR for evaluating knee MRI datasets by comparing readers' performance using MPR and conventional film MRIs. METHODS: Eight patients with internal derangement of the knee were studied. All had MRI datasets acquired in the sagittal plane using a three-dimensional gradient-echo fast imaging with steady-state precession (FISP) sequence. Arthroscopic surgery after MRI confirmed the presence of 6 anterior cruciate ligament (ACL) tears, 11 meniscal tears, and 5 normal menisci in this group. Four blinded readers, experienced in MRI of the knee, evaluated the images. The MRI datasets were then loaded onto a three-dimensional workstation and interpreted by the same readers using MPR. The MRI findings were correlated with arthroscopy. RESULTS: For diagnosis of tears of the ACL, sensitivity was 96% and specificity was 100% for both films and MPR. For detecting meniscal tears, sensitivity was 55% and specificity was 90%, using the filmed images, versus 64% and 85%, respectively, with MPR. These differences were not statistically significant by the sign test. Total time (technologist processing time plus radiologist reading time) for MPR was greater than for film interpretation by a factor of 1.12 (P < .05), and radiologist reading time for MPR was greater by a factor of 1.88 (P < .05). CONCLUSIONS: For sagittal three-dimensional FISP MRI datasets, real-time MPR is comparable with film interpretation for evaluation of ACL and meniscal injuries, but it increases the time required for diagnosis.

Adolescent↗
PubMed1993

Joseph E. Whitley Award. The effect of preradiology clinical training on the performance of radiology residents.

RATIONALE AND OBJECTIVES: A multi-institutional study was developed to evaluate whether having preradiology clinical training has an effect on the quality of performance of radiology residents assessed both after 1 year of training and at the end of the 4-year residency. MATERIAL AND METHODS: Five faculty members from each of nine collaborating institutions that accept residents both directly from medical school and with postgraduate clinical training completed 1,015 evaluation forms on their 203 residents who had just completed their first year of radiology training or had finished training in the past 2 years. Each resident was evaluated by two senior faculty, two junior faculty, and the residency program director using a cross-institutionally validated, behavior-oriented, standardized instrument that assessed five behavioral characteristics: conscientiousness, curiosity, interpersonal skills, confidence, and recognition of limits. The differences between residents who did and did not have preradiology clinical training were evaluated by analysis of variance and by simple effects testing. RESULTS: At the conclusion of training, no significant differences in resident performance were found between residents who did and did not have postgraduate clinical training before radiology residency. Among residents who had just finished their first year of training, those who had had clinical training scored significantly higher on four of the five behavioral scales. CONCLUSIONS: Clinical training before radiology residency does not correlate with any measurable benefit in performance at the end of radiology residency. Training programs should consider elimination of this requirement.

Adult↗
PubMed1993

Methods used for liver computed tomography scanning in community radiology practice.

RATIONALE AND OBJECTIVES: A survey conducted in 1987 of mostly academic radiologists revealed that 8 of 22 (36%) respondents used bolus enhanced dynamic technique when performing computed tomography (CT) of the liver. In the current study, the authors performed a new survey of private practice radiologists that was over four times larger and had more comprehensive questions. METHODS: An 18-item questionnaire was sent to 260 members of the American College of Radiology. The answers from 98 usable responses were tallied and analyzed. RESULTS: Forty-six percent of the radiologists polled use bolus enhanced dynamic CT. Thirty-three percent still use ionic contrast, and a significantly lower iodine dose was used when nonionic contrast was chosen. CONCLUSIONS: There is general agreement in the imaging literature that dynamic enhanced scanning is the method of choice for detecting liver masses with CT. The authors speculate that cost and convenience considerations strongly influence such decisions, because less than 50% of radiologists we polled use this somewhat more expensive and time-consuming technique.

Community Health Services↗
PubMed1993

Mandible enclosure of upper airway and weight in obstructive sleep apnea.

Although anatomic lesions and obesity can produce obstructive sleep apnea (OSA), most subjects with OSA have no recognizable anatomic lesion. We hypothesized that the occurrence of OSA is related to the size of the region enclosed by the mandible and the degree of obesity. We studied 30 subjects with a range of OSA and obesity with magnetic resonance imaging (MRI). MRI was performed with T-1 weighted sequences. Nocturnal polysomnography was performed in all subjects. Univariate regression analysis indicated there was a significant correlation between the number of apneas and hypopneas per hour of sleep (AH/h) and (1) the area enclosed by the mandible ramus (AMR1) (r = 0.48, p < 0.01) and (2) the distance from the teeth to the posterior mandible ramus (r = 0.39, p < 0.05). Stepwise multiple regression analysis indicated that weight, AMR1, and height explained 69% of the variance of AH/h (r2 = 0.69). We conclude that the occurrence of OSA in these subjects is related to the size of the region enclosed by the mandible as well as to their weight.

Adult↗
PubMed1993

Successful preoperative diagnosis and treatment of a saphenous vein coronary artery bypass graft aneurysm.

A 71-year-old man who underwent a coronary artery bypass using a saphenous vein bypass graft (SVG) in 1977 presented with a new mediastinal mass on chest radiography. A variety of imaging techniques were applied and magnetic resonance imaging (MRI) provided excellent anatomic detail of an aneurysm of the previously placed SVG. This condition was successfully treated with repeat operation, aneurysm resection, and placement of new bypass grafts. We recommend that any patient with a history of previous coronary artery grafting who presents with a mediastinal mass be evaluated for the possibility of a graft aneurysm. The best mediastinal imaging technique for this purpose appears to be an MRI scan.

Aged↗
PubMed1993

Adipose tissue deposition in sleep apnea.

To determine whether adipose tissue is deposited in the neck adjacent to the upper airway in patients with obstructive sleep apnea (OSA), we studied 21 subjects with OSA and nine without OSA using magnetic resonance imaging with a T-1 weighted spin echo sequence and polysomnography. We observed that patients with OSA had a larger volume of adipose tissue adjacent to their upper airway than did subjects without OSA.

Adipose Tissue↗
PubMed1992

Normal venous anatomy and collateral pathways in upper extremity venous thrombosis.

Collateral pathways are well known in superior vena cava occlusion but not in axillary or subclavian vein occlusion, even though these occlusions are becoming more common. In a series of 127 arm venograms obtained for suspected venous thrombosis, the authors found 32 instances of subclavian or axillary vein occlusion. The authors reviewed the cases for site of occlusion and definition of collateral pathways. In 15 cases, the occlusion was in the subclavian vein, with collateral flow established chiefly via veins in the neck. Ten cases of axillary vein occlusion with chest wall collateral pathways were identified. Seven cases could not be categorized. Knowledge of these pathways is useful for accurate interpretation of upper extremity venograms. A more thorough understanding of venous pathways in the upper body may aid in the treatment of patients with chronic disease and longterm indwelling central venous catheters.

Arm↗
PubMed1992

Ovarian masses revisited: radiologic and pathologic correlation.

Diagnosis of ovarian masses can be difficult because many pathologic conditions can affect the ovary and have similar clinical and radiologic manifestations. Knowledge of pathologic, age-specific characteristics can help refine the differential diagnosis. Ovarian masses are nonneoplastic (ovarian functional cysts, polycystic ovary disease, and ovarian torsion) or neoplastic (surface epithelial, sex cord-stromal, germ cell, and metastatic tumors). Functional cysts, if complicated by hemorrhage, can have a confusing ultrasonographic (US) appearance. Polycystic disease and torsion are easily diagnosed with US. Benign and malignant forms of serous and mucinous surface epithelial tumors can usually be differentiated with US. Imaging features of surface epithelial tumors of low malignant potential are nonspecific, resembling those of benign serous and mucinous tumors. Mature (benign) teratomas are usually cystic, with components of fat, soft tissue, and calcium, and are sonographically distinct from immature (malignant) teratomas, which are mostly solid. Sex cord-stromal tumors occur more often in menopausal or postmenopausal women and are typically solid. Metastatic disease is less common than other ovarian tumors; however, its radiologic appearance may resemble those of other masses.

Adult↗
PubMed1992

Computed tomographic evaluation of blunt abdominal trauma.

Given the magnitude of the problem of blunt abdominal trauma, we have the opportunity, through abdominal CT, of making a great impact on the health care of many patients. Through the efforts of early investigators and with continued refinements, great progress has been made in developing CT as an accurate, reliable emergency modality. With meticulous technique and careful interpretation, even subtle visceral, bowel, and mesenteric injuries can be detected. Close monitoring by an experienced tomographer and a good working relationship with referring clinicians can lead to prompt and appropriate clinical decisions.

Abdominal Injuries↗