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Biomedical subjects

J P Whalen

Publications and source records attributed to J P Whalen.

At least 19 recordsLinked to original sources
PubMed1992

Quantitative MRI studies for assessment of multiple sclerosis.

Although magnetic resonance imaging (MRI) is a valuable aid in the initial diagnosis of multiple sclerosis (MS), quantitatively MRI has been disappointing in staging and evaluating therapy protocols by means of serial examinations. In this study, image processing algorithms were developed for the global analysis of MR images of the cerebrum. Limited three-dimensional segmentation was achieved through histogram analysis by these algorithms, which are essentially operator independent. The effects of coil response and tip angles, patient positioning, and interslice gap thicknesses were examined for 10 MS patients with repeated examinations for a total of 72 images. Effects of technique and instrumentation errors were approximately 6%, and agreement between two independent operators for measuring the total MR pixel sum from periventricular effusions and intense MS plaques was better than 97% with a standard deviation of 2.9%.

Adipose Tissue↗
PubMed1992

Experimental design and fabrication of birdcage resonators for magnetic resonance imaging.

Although the birdcage resonator has been theoretically described for single- and multinuclear operation, this study provides the basic experimental guidelines needed for the fabrication and testing of such coils for various geometries and resonant frequencies from 10 to 95 MHz. The correlation of coil dimensions and resonant frequencies with individual inductance elements, L1 and L2, is also shown. Experimentally derived algorithms are presented for the determination of the capacitance needed for low-pass resonators based on measurements of the coil's "global" inductance. Ten low-pass birdcage coils with eight legs were evaluated and their four resonant frequencies were within 4% of theoretical predictions.

Algorithms↗
PubMed1990

The effect on grades of the timing and site of third-year internal medicine clerkships.

Two important factors affecting the performances of third-year medical students on their basic internal medicine clerkships were investigated: (1) the effect on their grades of when in the academic year they took the internal medicine clerkship, and (2) the effect on their grades of the site of the clerkship. During the academic years 1983-84, 1984-85, and 1985-86, the Department of Internal Medicine of the University of Illinois College of Medicine at Chicago conducted 12-week junior clerkships at six hospital sites. The study analyzed the 535 students' subjective grades, clerkship examination scores, final grades, and National Board of Medical Examiners Part I (NBME-I) scores. Although students' performances as characterized by subjective evaluations did not improve as the academic year progressed, mean scores on clerkship examinations improved steadily during the same period. The site of the clerkship, whether a community-affiliated hospital or a medical center hospital, affected neither subjective nor objective grades.

Clinical Clerkship↗
PubMed1990

Optimizing radiologic costs in the DRG environment.

Previously developed consensus algorithms expressing a suggested radiologic workup for the diagnostic related groups (DRGs) specified by the prospective reimbursement policy have proven to be useful tools for investigating radiologic decision making and the resulting economic implications. The mathematical equations for determining diagnostic and therapeutic costs for two alternative algorithms for suspected acute cholecystitis are formulated. Illustrative examples and graphic displays are given regarding how such algorithms and equations are useful in finding answers to questions about the appropriate diagnostic workup, time, and cost. Exploration of the effect of different parameter values on the choice of the appropriate algorithm is illustrated.

Algorithms↗
PubMed1989

Computed tomography versus magnetic resonance imaging of the brain. A collaborative interinstitutional study.

A retrospective study (1983-1984) of magnetic resonance imaging (MRI) and computed tomography (CT) examinations in 471 patients with known pathology in the brain and craniocervical junction was conducted in order to determine the relative efficacy of MRI versus CT. All MRI examinations involved slice thickness greater than 10 mm, and only single-slice single-echo or multislice single-echo imaging techniques were available. These studies were evaluated independently by two neuroradiologists from a panel of six for anatomic abnormalities, lesion contrast, and radiologist's impression. Results, which excluded microadenomas of the pituitary and approximately 9% of studies in which consensus was not achieved by the readers, were as follows: (1) 14% of the studies were positive on MRI but normal on CT; (2) in 55% of the studies, MRI was better than CT; (3) MRI was equal or better than CT in 95% of the studies; and (4) CT was better than MRI in 5% (21/421) of the examinations. There were no patients in this series where CT was positive but MRI missed the abnormality.

Adult↗
PubMed1988

Chondromalacia of the patella. Bone imaging correlated with arthroscopic findings.

One hundred adult sports medicine patients with clinical findings suggesting chondromalacia of the patella underwent bone imaging. Of these patients, 50 eventually underwent arthroscopic surgery and the remaining 50 were treated conservatively. The intensity of abnormally increased scintigraphic activity in the patella correlated closely with the grade of chondromalacia observed by the arthroscopist. Bone imaging also was of value in directing the arthroscopist to clinically unsuspected torn menisci. In conclusion, for sports medicine patients with clinical findings suggestive of chondromalacia of the patella, bone imaging contributes to an accurate diagnosis and appropriate surgical planning.

Adult↗
PubMed1988

Unusual stress fracture of the scapula in a jogger.

A case of fracture of the right scapula in the superomedial portion with no history of direct trauma is presented. It is most likely due to jogging with weights in both hands. A brief review of scapular fractures is also reported.

Adult↗
PubMed1988

Diagnostic protocols for radiologic efficiency.

Starting January 1988, New York State started an all-payor prospective reimbursement for inpatient hospitalizations. Medicare had already adopted a prospective reimbursement system for its patients during the previous year. This article reviews our departmental efforts to prepare for the consequences of these new policies.

Algorithms↗