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Biomedical subjects

R S Hellman

Publications and source records attributed to R S Hellman.

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

The role of single photon emission computed tomography brain imaging with 99mTc-bicisate in the localization and definition of mechanism of ischemic stroke.

99mTc-bicisate (99mTc-ECD) is a new brain perfusion imaging agent formulated from a radiochemically stable kit (Neurolite). A multicenter trial was conducted to determine the sensitivity and specificity of single photon emission computed tomography (SPECT) imaging with 99mTc-bicisate in the localization of ischemic stroke; 170 subjects were enrolled, 128 patients with stroke and 42 controls. Imaging results from 148 subjects (107 stroke patients and 41 controls) were considered evaluable. In the evaluable subjects, SPECT brain imaging with 99mTc-bicisate (21.0 +/- 2.5 mCi) was interpreted without clinical information and was compared with a final assessment using all clinical, diagnostic, and laboratory procedures except the 99mTc-bicisate SPECT results. 99mTc-bicisate was safe and well-tolerated. SPECT imaging with 99mTc-bicisate demonstrated a specificity of 98% and a sensitivity of 86% for localization of strokes (kappa, 0.75; 95% confidence interval, 0.64-0.86). Results were unchanged over time and were similar for all stroke mechanisms except for lacunar disease (sensitivity, 58%). In a secondary analysis, a normal image or small, deep (e.g., subcortical) perfusion defect was highly predictive of a lacunar mechanism. Defects involving the cortical surface were strongly associated with nonlacunar mechanisms. SPECT imaging with 99mTc-bicisate is a sensitive marker in the localization of perfusion defects associated with ischemic stroke and may assist in the determination of the underlying mechanism of a stroke.

Adult↗
PubMed1993

Detection of chronic coronary artery disease: value of pharmacologically stressed, dynamically enhanced turbo-fast low-angle shot MR images.

OBJECTIVE: The potential of MR imaging for evaluating myocardial perfusion and viability may make it the imaging procedure of choice for examining patients with ischemic heart disease. Accordingly, the purpose of this study is to determine the value of pharmacologically stressed, dynamically enhanced turbo-fast low-angle shot (FLASH) MR imaging in detecting chronic coronary artery disease. SUBJECTS AND METHODS: Five patients who had coronary angiography within the past 6-12 months were included in the study. After injection of 0.56 mg/kg of dipyridamole over 4 min, a bolus of 0.05 mg/kg of gadopentetate dimeglumine and subsequently 10 mCi (370 MBq) of 99mTc-sestamibi were injected. Short-axis turbo-FLASH images were obtained before injection and immediately, 1 min, 3 min, and 5 min after the injection of contrast material. Stress single-photon emission computed tomography (SPECT) images of the heart were obtained 60 min after the 99mTc-sestamibi injection. One and a half hours after an additional 30 mCi (1110 MBq) of 99mTc-sestamibi was injected, SPECT images were obtained with patients at rest. Prospective MR imaging evaluation of these five patients was performed by radiologists who did not know any of the imaging data. The MR imaging studies were compared with the near simultaneous 99mTc-sestamibi SPECT studies and with recent coronary angiograms. RESULTS: Thirteen myocardial segments were diagnosed as abnormal when 99mTc-sestamibi SPECT was used as the gold standard (12 reversible defects and one fixed defect). Twelve segments were normal on the 99mTc-sestamibi SPECT study. With SPECT as the gold standard, prospective MR imaging had a sensitivity of 77% and a specificity of 75%, whereas retrospectively it had a sensitivity of 92% and a specificity of 75%. With recent coronary angiography as the gold standard, prospective MR imaging had a sensitivity of 81% and a specificity of 100%. The quantitative data did not improve the accuracy of the qualitative analysis. CONCLUSION: Our results suggest that accurate prospective identification of chronic coronary artery disease may be possible with dynamically enhanced, pharmacologically stressed, turbo-FLASH MR imaging. Studies of additional patients to confirm this initial impression are warranted.

Adult↗
PubMed1992

Diagnostic reliability of radionuclide ventriculography in detecting left ventricular hypertrophy. Echocardiographic and ECG correlations.

Left ventricular hypertrophy (LVH) is frequently present in patients referred for radionuclide ventriculography (RVG) for evaluation of left ventricular function. During interpretation of these studies, the nuclear medicine physician may have the subjective impression that increased septal thickening is present because of the abnormally prominent separation of the right and left ventricular blood pools. To examine the diagnostic reliability of this finding, we retrospectively reviewed the RVG studies of 43 consecutive patients and correlated the finding of subjectively increased septal thickness with established echocardiographic (ECHO) criteria and commonly used electrocardiographic (ECG) indices of LVH. Using standard ECHO measurements of septal thickness as a gold standard, RVG interpretation of septal thickening demonstrated a sensitivity of 0.69, specificity of 0.70, and accuracy of 0.70. When compared with standard ECG criteria for LVH, RVG performed quite favorably in the diagnosis of LVH confirmed by ECHO left ventricular mass index. We conclude that scintigraphic evidence of LVH should be reported when RVG studies are interpreted.

Adult↗
PubMed1992

Increased sacroiliac joint uptake after lumbar fusion and/or laminectomy.

Of 753 adult patients undergoing SPECT and planar bone scintigraphy for the evaluation of low back pain, 43 (6%) showed either unilateral or bilateral increased sacroiliac joint (SIJ) uptake. Five of the 58 abnormal joints were only identified with SPECT (9%), whereas 20 of the 58 abnormal joints were much more convincingly demonstrated by SPECT (34%). Fifteen of the 43 patients with increased SIJ uptake had undergone prior lumbar laminectomy and/or spinal fusion. Such spinal surgery can increase impact loading on the SIJ, leading to mechanical overload and sacroiliitis. Degenerative joint disease, trauma, or other benign pathology accounted for the remaining patients with increased SIJ uptake. The authors conclude that for patients with a history of lumbar spinal fusion and/or laminectomy, increased SIJ uptake usually is caused by altered spinal mechanics rather than malignancy or infection.

Adult↗
PubMed1992

High-resolution bone scintigraphy of the adult wrist.

Bony anatomic landmarks of the wrist (e.g., pisiform, hook of hamate, radioulnar joint, and styloid processes of the radius and ulna) were routinely identified in 28 adult patients examined for wrist pain. With the wrists prone and immobilized, bone scintigrams were obtained for 500,000 counts with an asymmetric (133 to 161 keV) Tc-99m energy window and either a converging (best choice) or straight-bore, high-resolution collimator. High-resolution scintigraphy precisely localized degenerative joint disease (nine patients), scaphoid fractures (five), pisiform fracture (one), lunate avascular necrosis (one), radioulnar arthritis (one), septic or inflammatory arthritis (six), ulnocarpal impingement (two), and reflex sympathetic dystrophy syndrome (two). Images obtained palm down with the wrist in ulnar deviation helped identify increased uptake within the scaphoid. Fracture and significant bone or joint disease were excluded in one patient.

Adult↗
PubMed1991

Brain single photon emission computed tomography: newer activation and intervention studies.

Single-photon emission computed tomography (SPECT) regional cerebral blood flow (rCBF) findings using non-xenon 133 tracers in combination with activation and intervention techniques are reviewed. Examination of the currently available data indicates that it is possible to detect the effects of a variety of activations and interventional procedures using SPECT rCBF with non-xenon 133 tracers. There are still many issues to be resolved before SPECT can reach the level of sophistication attained by xenon 133 and positron emission tomography in studying rCBF during activation or intervention. However, research to date indicates that SPECT rCBF studied with tracers other than xenon 133 has an excellent potential for increasing the ability to differentiate normal and pathological states.

Adolescent↗
PubMed1991

Concentration of Tc-99m MDP in ovarian carcinoma and its soft tissue metastases.

A patient with ovarian carcinoma was evaluated for skeletal metastasis with a routine whole body bone scan. Although no bone metastases were visualized, there was dramatic accumulation of tracer in the soft tissues of the abdomen. CT revealed calcifying soft tissue metastases on the liver surface, the bowel serosa, and in the pelvis corresponding to the abnormal areas of Tc-99m MDP uptake. Tumor necrosis and ongoing calcification within the metastatic sites are possible explanations for this unusual soft tissue concentration of the bone-seeking radiopharmaceutical. In patients with metastatic ovarian carcinoma, careful review of extraosseous regions on bone scan images may provide valuable diagnostic information.

Abdominal Neoplasms↗
PubMed1991

Right aortic arch: demonstration by first-pass and multigated radionuclide ventriculography.

Right aortic arch is a rare congenital anomaly associated with abnormal development of the paired embryological aortic arches. While various abnormalities of the great vessels have been described using both first-pass and multigated radionuclide ventriculographic studies, diagnosis of a right-sided aortic arch has typically required a radiographic contrast technique. We present a case of a patient with a suspected right-sided aortic arch diagnosed by radionuclide methods.

Adult↗
PubMed1991

Isolated muscular sarcoidosis causing fever of unknown origin: the value of gallium-67 imaging.

An unusual case of a patient with a long-standing fever of unknown origin (FUO) is presented whose gallium-67 (67Ga) images revealed increased activity only in the calf muscles bilaterally. Other imaging modalities also failed to show chest or other abnormal findings. Subsequent biopsy of the right gastrocnemius muscle revealed noncaseating granulomas consistent with the diagnosis of sarcoidosis. When using 67Ga to evaluate a patient with a FUO, imaging of the extremities should always be included. Also, when abnormal Ga-67 uptake is present in the extremities, sarcoidosis should be included in the differential diagnosis.

Adult↗
PubMed1990

An overview of the contribution of regional cerebral blood flow studies in cerebrovascular disease: is there a role for single photon emission computed tomography?

Regional cerebral blood flow (rCBF) findings and their application to cerebrovascular disease are reviewed. Although the coupling of cerebral blood flow and metabolism are best studied with positron emission tomography, single-photon emission computed tomography measurements of rCBF can contribute to patient management. Potential indications for the use of rCBF functional brain imaging include differential diagnosis, early prediction of late recovery in the late subacute and chronic phases of stroke (3 months or more postonset), and evaluation of vasospasm following subarachnoid hemorrhage.

Cerebrovascular Circulation↗
PubMed1990

The value of oblique angle reorientation in SPECT bone scintigraphy of the hips.

SPECT bone scintigraphy has been shown useful for detecting avascular necrosis (AVN) of the femoral heads. Because the femoral necks project in a 15-20 degree posterior angulation from the coronal plane, the femoral head is partially superimposed upon the acetabulum in standard coronal SPECT images. To avoid this problem, the authors now perform oblique angle reorientation of all hip SPECT studies. This new technique, which allows display of the hip in a more anatomic fashion and better definition of hip abnormalities, is described. No new data acquisition is needed, and only a small amount of extra time is required for reconstruction.

Adult↗
PubMed1990

The radioactive handkerchief sign. A contamination artifact in I-131 imaging for metastatic thyroid carcinoma.

False-positive findings suggestive of metastatic functioning thyroid carcinoma have been well documented in I-131 whole-body imaging. These artifacts are often associated with contamination from radioiodine-containing body secretions. Recently, a contaminated handkerchief on an iodine-131 whole-body scan was reported. In the following study, two additional cases involving the sequestration of I-131 contaminated handkerchiefs in patients' pockets are presented, and the literature regarding these false-positive findings is reviewed. Although rare, this "radioactive handkerchief sign" may cause serious misinterpretation of a focal radioiodine accumulation.

Adult↗
PubMed1990

Pulmonary embolism as an indicator of occult malignancy.

A case that demonstrates the relationship between malignancy and pulmonary throboembolic disease is presented. Pulmonary embolism, which was diagnosed on a ventilation-perfusion lung scan, initiated a search for the etiology of this condition. Normal examination of the deep venous system of the legs prompted further investigation, which ultimately led to the endoscopic diagnosis of poorly differentiated gastric carcinoma.

Gastroscopy↗
PubMed1990

Accuracy and precision of radionuclide measurement of CSF oscillation in the spine.

A technique for simultaneously measuring pulsation, translation and diffusion of a radioactive tracer in the spinal cerebrospinal fluid (CSF) has been described. To evaluate the accuracy and precision of this method for measuring CSF oscillation in the spine, an apparatus was designed that moved a radioactive source sinusoidally with known amplitude along a line. With list mode acquisition of radioactive emissions, the amplitude of oscillation was measured for a series of peak-to-peak amplitudes ranging from 0.01 mm to 3.8 mm. For oscillations larger than 0.35 mm peak-to-peak, measured values were within 6.1 percent of the expected values. For the spinal CSF, oscillation larger than 0.4 mm should be measured accurately with this technique.

Cerebrospinal Fluid↗
PubMed1990

Idiopathic pulmonary fibrosis. A rare cause of scintigraphic ventilation-perfusion mismatch.

A case of idiopathic pulmonary fibrosis with multiple areas of mismatch on ventilation-perfusion lung imaging in the absence of pulmonary embolism is presented. Idiopathic pulmonary fibrosis is one of the few nonembolic diseases producing a pulmonary ventilation-perfusion mismatch. In this condition, chest radiographs may not detect the full extent of disease, and xenon-133 ventilation imaging may be relatively insensitive to morbid changes in small airways. Thus, when examining patients with idiopathic pulmonary fibrosis, one should be aware that abnormal perfusion imaging patterns without matching ventilation abnormalities are not always due to embolism. In this setting, contrast pulmonary angiography is often needed for accurate differential diagnosis.

Diagnosis, Differential↗
PubMed1989

The effect of thalamic stimulation in processing of verbal stimuli in dichotic listening tasks: a case study.

In dichotic listening tasks, the (dominant) right ear's superiority in processing verbal stimuli has been attributed to its direct anatomic connection with the left dominant hemisphere. The role played by extralinguistic factors, such as attention and functional tuning of the associated cortical structures, has not been carefully examined. This investigation was undertaken to evaluate the effects of the left thalamic electric stimulation on the processing (recognition and recall) of dichotically presented CVC verbal stimuli in a patient being treated for chronic pain. We report the positive effects of electric stimulation (confirmed by increased subcortical metabolic activity using SPECT, a brain imaging technique) on the processing of dichotically presented verbal stimuli.

Attention↗