Search PubMed⌕ Search

Biomedical subjects

R S Hellman

Publications and source records attributed to R S Hellman.

At least 73 records · Page 4Linked to original sources
PubMed1987

Thalamic functional tuning of the cortex in dichotic listening tasks.

In dichotic listening tasks, the (dominant) right ear's superiority in processing verbal stimuli has been attributed to its direct access to the linguistically dominant left hemisphere. The roles played by the extralinguistic factors, such as induced attentiveness and functional tuning of the auditory system, have not been carefully examined. The evidence for the facilitating effects of subcortical stimulation on processing dichotic stimuli is presented.

Dichotic Listening Tests↗
PubMed1987

Comparison of high-resolution MRI and SPECT bone scintigraphy for noninvasive imaging of the temporomandibular joint.

Prospective evaluation by magnetic resonance imaging (MRI) and both single photon emission computed tomography (SPECT) and planar bone scintigraphy was undertaken in 31 temporomandibular joints (TMJs) of 21 symptomatic patients. When compared with the results of subsequent arthrography, MRI (0.88) was more sensitive than SPECT (0.76) or planar (0.56) scintigraphy for detection of internal derangement of the TMJ. A diagnostic sensitivity of 0.96 was achieved when the results of either MRI or SPECT was considered evidence of internal joint derangement. Five symptomatic TMJs, clinically thought to be abnormal, were positive on SPECT but showed no evidence of anterior disk displacement at the time of arthrography. In such instances, SPECT may be detecting functionally significant altered joint mechanics that are not evident on anatomic imaging of the TMJ.

Adolescent↗
PubMed1986

Comparison of single-photon emission computed tomography with [123I]iodoamphetamine and xenon-enhanced computed tomography for assessing regional cerebral blood flow.

Regional CBF (rCBF) images obtained from xenon-enhanced computed tomography (XeCT) and single-photon emission computed tomography (SPECT) with N-isopropyl-p-[123I]iodoamphetamine (IMP) done with a rotating gamma-camera were compared in nine patients. Both XeCT and SPECT/IMP demonstrated flow abnormalities at all sites of infarction identified by CT, while detecting reduced rCBF in areas normal by CT in eight of the nine patients. All areas that were abnormal on XeCT were abnormal on the comparable SPECT/IMP images. The major advantages of XeCT are its greater resolution and potential for noninvasive quantitation of rCBF, while the major advantage of SPECT/IMP is its visualization of the entire brain on transverse, coronal, and sagittal sections.

Amphetamines↗
PubMed1986

Evaluation of distance-weighted SPECT reconstruction for skeletal scintigraphy.

In 15 patients who had undergone skeletal scintigraphy for evaluation of low back pain, single-photon emission computed tomography (SPECT) reconstruction techniques of distance-weighted filtered backprojection (new method) and non-distance-weighted filtered backprojection (standard method) were compared. Mid-spine sagittal views differing only by reconstruction methods were evaluated by trained observers and by a quantitative profile technique. When asked to compare image quality, the observers demonstrated a clear preference for images reconstructed by the new method. Profile quantitation showed significantly greater contrast in more superficial structures with the new method.

Back Pain↗
PubMed1986

Early diagnosis of acute postoperative renal transplant rejection by indium-111-labeled platelet scintigraphy.

A prospective evaluation of 111In-labeled platelet scintigraphy (IPS) for the early diagnosis of acute postoperative renal transplant rejection (TR) was undertaken. The results of IPS were compared with in vitro biochemical tests, the clinical finding of graft tenderness, and combined [99mTc]DTPA and [131I]orthoiodohippurate scintigraphy. With a sensitivity of 0.93 and a specificity of 0.95, IPS provided otherwise unavailable diagnostic information. Furthermore, postoperative IPS was a good predictor of long-term allograft survival.

Acute Disease↗
PubMed1985

Painful spondylolysis or spondylolisthesis studied by radiography and single-photon emission computed tomography.

Planar bone scintigraphy (PBS) and single-photon emission computed tomography (SPECT) were compared in 19 adults with radiographic evidence of spondylolysis and/or spondylolisthesis. SPECT was more sensitive than PBS when used to identify symptomatic patients and sites of "painful" defects in the pars interarticularis. In addition, SPECT allowed more accurate localization than PBS. In 6 patients, spondylolysis or spondylolisthesis was unrelated to low back pain, and SPECT images of the posterior neural arch were normal. The authors conclude that when spondylolysis or spondylolisthesis is the cause of low back pain, pars defects are frequently heralded by increased scintigraphic activity which is best detected and localized by SPECT.

Adolescent↗
PubMed1985

Chronic knee pain assessed by SPECT: comparison with other modalities.

Twenty-seven patients with chronic knee pain were examined prospectively using conventional radiography, radionuclide angiography, planar bone scintigraphy, and single-photon emission computed tomographic (SPECT) bone scintigraphy. When the results of subsequent arthroscopic examination of all three compartments of the knee were correlated with those of the noninvasive methods, SPECT bone scintigraphy was found to be most sensitive for evaluating the extent of osteoarthritis. Differences in detection sensitivity for articular cartilage damage and synovitis were greatest in the patellofemoral compartment. The frequency with which hyperemia was present in association with cartilage damage and synovitis indicates that osteoarthritis of the knee is capable of producing hyperemia and further implies that increased perfusion cannot be used to distinguish with confidence between osteoarthritis and septic processes involving the knee. SPECT (1.00) and planar (0.91) bone scintigraphy were highly sensitive indicators of torn menisci in a subgroup of 14 patients, each having a prearthroscopic clinical diagnosis of a torn meniscus. This result suggests that for patients with chronic knee pain and clinical suggestion of a torn meniscus, bone scintigraphy has significant potential as a high-sensitivity, prearthroscopic screening examination.

Adolescent↗
PubMed1985

Photon deficient bone metastasis of hepatocellular carcinoma with avid gallium-67 uptake.

While bone metastases producing photon deficient defects on bone scintigraphy have previously been reported, this finding has not been emphasized for hepatocellular carcinoma (HCC). Furthermore, "filling-in" of such photon deficient defects with 67Ga at skeletal sites of metastatic HCC has not been described. In this case report, the combination of a photon deficient defect on bone scintigraphy and avid accumulation of 67Ga in this same area was of value in confirming the diagnosis of metastatic HCC.

Adult↗
PubMed1985

Detection of femoral head avascular necrosis in adults by SPECT.

Twenty-one adult patients with the clinical diagnosis of avascular necrosis (AVN) of the femoral head were examined with radionuclide angiography, planar bone scintigraphy, and single photon emission computed tomography (SPECT). A final diagnosis of AVN was established for 15 symptomatic patients with a total of 20 involved hips. SPECT and planar bone scintigraphy were considered positive for AVN only if a photopenic bony defect could be identified. Using SPECT bone scintigraphy, 12 of 15 symptomatic patients and 17 of 20 involved hips (sensitivity of 0.85) were correctly identified, whereas with planar imaging only eight of 15 patients and 11 of 20 involved hips were detected. There were no false-positive diagnoses on SPECT or planar bone scintigraphy. In addition, hyperemia in the region of the proximal femoral metaphysis was demonstrated in six of 20 involved hips. It is concluded that by identifying a photopenic defect that is not evident on planar views, SPECT can contribute to the diagnosis of AVN of the femoral head. In addition, metaphyseal hyperemia appears to be a promising new scintigraphic sign of AVN worthy of further investigation.

Adult↗
PubMed1984

Scintigraphic skeletal "doughnut" sign due to giant cell tumor of the fibula.

Although the "doughnut" sign in brain scintigraphy is a well known phenomenon, similar findings have recently been reported in bone scintigraphy in osseous and nonosseous lesions. A skeletal doughnut sign in bone scintigraphy caused by giant cell tumor of the proximal fibula is presented with a brief review of literature.

Adult↗
PubMed1984

Gamma camera energy windows for Tc-99m bone scintigraphy: effect of asymmetry on contrast resolution. Work in progress.

By raising the lower threshold of the Tc-99m energy window, rejection of scattered photons can be made more efficient. Unfortunately, with most gamma cameras significant nonuniformities are produced when the window is changed to an asymmetric setting. Recently introduced designs with gain stabilization of the photomultiplier tubes and improved energy correction maintain field uniformity even for an asymmetric window. To assess the impact of an asymmetric energy window on clinical images, 33 Tc-99m-MDP scintigrams of the lumbar spine were taken with symmetrical (126-154 keV) and asymmetric windows (135-154 keV). Bone:soft tissue ratios improved with the asymmetric window, and the resulting images were preferred by the physicians questioned.

Abdomen↗
PubMed1984

Concentration of In-111-oxine-labeled autologous leukocytes in noninfected and nonrejecting renal allografts: concise communication.

Autologous leukocytes labeled with In-111 oxine (ILL) concentrated in the renal allografts of eight patients for whom transplant rejection, infection, or acute tubular necrosis (ATN) could be excluded. All patients had good-to-adequate renal function at the time of ILL scintigraphy, and none developed rejection or renal transplant failure during a 1-mo follow-up period. It is concluded that normally functioning renal allografts without evidence of rejection, infection, or ATN often will concentrate ILL. When a baseline study is not available for comparison, this phenomenon limits the value of ILL scintigraphy as a diagnostic test for transplant rejection or infection.

Adult↗
PubMed1983

Internal derangement of the temporomandibular joint: detection by single-photon emission computed tomography. Work in progress.

The diagnostic accuracy of both planar and single-photon emission computed tomography (SPECT) bone scintigraphy, radionuclide angiography, arthrography, and conventional radiography was evaluated in 36 patients with temporomandibular joint (TMJ) dysfunction undergoing preoperative testing. The sensitivity of SPECT bone scintigraphy (0.94) was comparable with arthrography (0.96) and significantly better than planar bone scintigraphy (0.76), radionuclide angiography (0.35), and transcranial lateral radiographs (0.04). While data for a larger asymptomatic control population are needed, preliminary results give SPECT a diagnostic specificity of 0.70 for internal derangements of the TMJ requiring surgical correction. It is concluded that SPECT bone scintigraphy is a useful noninvasive imaging test to screen for internal derangement of the TMJ.

Adolescent↗
PubMed1983

Estimation of absolute left ventricular volume from gated radionuclide ventriculograms. A method using phase image assisted automated edge detection and two-dimensional echocardiography.

Twenty-four patients underwent gated cardiac blood pool (GBP) imaging, two-dimensional echocardiography (2-D echo), and single-plane contrast ventriculography (within 24 hours). Variable left ventricular (LV) regions of interest on GBP images were identified by an automated threshold radial search. To avoid excluding LV counts we indexed the search threshold to the threshold identified by a phase image generated by Fourier analysis. LV depth calculated by 2-D echo was used for attenuation correction of LV counts. LV end-diastolic volume (EDV) and end-systolic volume (ESV) were calculated by dividing attenuation, background and deadtime corrected LV count rates by the background corrected count rate/ml of venous blood drawn during the study. Correlations between radionuclide and contrast volumes were good (EDV + ESV r = 0.97, EDV r = 0.94, ESV r = 0.95). Regression lines were close to the lines of identity. This method, in which GBP imaging and automated LV edge finding are complemented by 2-D echo for count attenuation correction, demonstrated reliable and reproducible noninvasive estimates of absolute LV volume.

Adult↗