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Biomedical subjects

S S Wadhwa

Publications and source records attributed to S S Wadhwa.

14 recordsLinked to original sources
PubMed1999

Tl-201 myocardial perfusion SPECT: role of nitrate-augmented redistribution.

PURPOSE: TI-201 myocardial perfusion SPECT is commonly used to assess myocardial perfusion and viability. Nitrate-augmented redistribution with repeated injection facilitates the detection of reversible segments compared with standard redistribution. In this study, we investigated the potential of nitrate augmentation to improve myocardial perfusion and viability assessment without repeated injection and we also compared nitrate-augmented redistribution with delayed redistribution. METHODS: Eighteen patients underwent a stress-redistribution TI-201 SPECT study. Immediately after redistribution SPECT, each patient was administered 0.6 mg glyceryl trinitrate and nitrate-augmented redistribution SPECT acquired 30 minutes later. Each patient then returned the next day and was injected with a booster dose of TI-201 30 minutes before the delayed redistribution SPECT acquisition. For each SPECT study, the myocardium was divided into 11 segments, and perfusion to each segment was scored on a four-point scale by consensus. An overall cardiac perfusion score was derived by summing the perfusion score for each segment. RESULTS: Reduced stress perfusion was identified in 150 segments: 23 (15.3%) had improved perfusion after redistribution; 60 (40%) segments had improved perfusion after nitrate-augmented redistribution; 52 (34.7%) segments with reduced stress perfusion had improved perfusion after delayed redistribution. The cardiac perfusion score after stress was 15.9+/-5.5 (means+/-SD). The score increased to 17.4+/-5.4 after redistribution. The perfusion score improved to 19.7+/-5.8 (P < 0.05 versus redistribution) after nitrate augmentation. The cardiac perfusion score, 19.2+/-6.4, did not improve further after delayed redistribution. CONCLUSIONS: TI-201 SPECT with nitrate-augmented redistribution is as good or better than delayed redistribution with repeated injection for myocardial perfusion and viability assessment. TI-201 SPECT with nitrate-augmented redistribution has significant logistical and economic advantages over traditional delayed redistribution with TI-201 repeated injection.

Coronary Circulation↗
PubMed1999

Tc-99m HDP uptake in cardiac amyloidosis.

Amyloidosis is characterized by the soft-tissue deposition of amyloid protein. It may occur as a primary disorder but more often is seen as a manifestation of chronic illness. Scattered reports of the affinity of amyloid for bone scanning agents have appeared over many years. Isolated cardiac uptake of Tc-99m HDP is described in a patient with biopsy-proved cardiac amyloidosis on a background of tuberculosis, prostate cancer, and coronary artery disease.

Aged↗
PubMed1999

Tl-201 and Ga-67 scintigraphy in non-Hodgkin's lymphoma.

Ga-67 scintigraphy is routinely used to stage and monitor non-Hodgkin's lymphoma (NHL). It is highly sensitive in high-grade NHL but less so in intermediate- and low-grade NHL. Several studies have reported the use of Tl-201 in the low and intermediate grades of NHL and found it superior in low-grade NHL. In this study, the authors evaluated the utility of combined Ga-67 and Tl-201 scintigraphy in low, intermediate, and unusual types of NHL. Combined Tl-201 and Ga-67 scintigraphy were done in 33 patients (18 women, 15 men; age range, 21-91 years; mean age, 56 years). Tl-201 and Ga-67 had similar overall patient sensitivity in the 33 patients studied. However, the use of both agents increased the overall patient sensitivity from 67% (for Ga-67 only) to 82% and improved the overall site detection from 59 positive sites with Ga-67 to 81 abnormal sites with both Tl-201 and Ga-67. The combined use of Tl-201 and Ga-67 scintigraphy in low- and intermediate-grade NHL resulted in increased disease and site detection and is beneficial for clinical follow-up.

Adult↗
PubMed1999

Anterior chest wall pain in postpartum costochondritis.

Costochondritis is a common diagnosis in patients with anterior chest wall pain in whom serious disease has been excluded. The diagnosis is usually made on clinical grounds, because laboratory and imaging investigations usually provide little information. The authors describe a young woman with postpartum costochondritis and discuss the role of bone scintigraphy in confirming the clinical diagnosis.

Adult↗
PubMed1999

Gated TI-201 myocardial perfusion SPECT: application of energy window optimization.

PURPOSE: TI-201 scintigraphy is plagued with poor image quality because of the low-energy photons of TI-201 decay. Traditionally, a narrow 20% window centered on 71-72 keV has been used to improve sensitivity. Recent studies indicate that better imaging may be possible by optimizing the energy window to 34% centered on 77 keV. In this study, energy window optimization (EWO) was applied to gated TI-201 myocardial perfusion SPECT, and myocardial functional parameters were compared for gated TI-201 SPECT and gated Tc-99m sestamibi (Tc-99m MIBI) SPECT. METHODS: Count statistics for standard and optimal TI-201 myocardial scintigraphy were noted in 25 patients by assessing the total counts in a mid-ventricular slice of a rest-gated TI-201 myocardial SPECT study. The feasibility of performing functional studies with the application of EWO to TI-201 was assessed using the count statistics of a mid-ventricular slice of an optimized gated TI-201 SPECT study and a gated Tc-99m MIBI SPECT study. The functional parameters (ejection fraction, wall motion, and thickening) of TI-201 with EWO and Tc-99m MIBI were compared in 60 patients who underwent rest-gated TI-201 SPECT followed by poststress gated Tc-99m MIBI SPECT. The left ventricular ejection fraction was calculated using commercially available software, whereas wall thickness and motion were assessed by the consensus of two readers. RESULTS: The application of EWO increased available counts by more than 25%. It also resulted in sufficient counts being available to perform gated TI-201 SPECT without increasing acquisition times or the dose of TI-201. The average ejection fraction was 60.4% for gated TI-201 SPECT and 59.6% for gated Tc-99m MIBI SPECT (not significantly different). Overall, the image quality was rated excellent in 12% for TI-201 and Tc-99m MIBI and good in 50% and 62%, respectively, and poor in 38% and 26%, respectively. CONCLUSION: The application of EWO to TI-201 SPECT allows myocardial functional parameters to be assessed without having to increase the acquisition times or the administered dose of TI-201.

Adult↗
PubMed1998

Benign oral disease as a cause of false-positive iodine-131 scans.

Post-thyroidectomy I-131 whole-body scintigraphy is an important aspect in the management of patients with thyroid cancer. The scan is used to detect residual thyroid tissue and distant functioning metastases. Extrathyroid I-131 accumulation does not always denote metastatic disease, and several potential sources of false-positive I-131 scans have been identified. This report presents four cases of benign oral disease as a cause of false-positive I-131 uptake. Benign oral disease has not been documented previously as an important source of false-positive I-131 whole-body scans.

Adult↗
PubMed1995

Meningitis caused by Streptococcus pneumoniae showing high level resistance to penicillin.

A case of meningitis caused by a strain of Streptococcus pneumoniae (SPn) showing high level resistance to penicillin is described. The patient responded to a combination of high dose penicillin and ceftriaxone. After reviewing the Australian situation and the world literature, we propose that empiric treatment of SPn meningitis in Australia should consist of high dose penicillin plus a third generation cephalosporin, with appropriate modification once the identification of the organism and its susceptibilities are confirmed.

Aged↗
PubMed1988

Gradual reintroduction of oxygen reduces reperfusion injury in cat stomach.

Recent studies have shown that oxygen-derived free radicals are responsible for a major portion of ischemia-reperfusion injury in the stomach. The oxygen radicals are produced during reperfusion when oxygen delivery to the tissue increases. In the present study we investigate the effect on mucosal injury of regulating the rate of reintroduction of oxygen to the stomach after ischemia. Local gastric ischemia was achieved by reducing celiac artery pressure to 30 mm Hg for 1 h. Ischemic injury was assessed by measuring the loss of 51Cr-labeled red blood cells across the gastric mucosa. Mucosal blood loss was negligible before and during the ischemia period but increased to 0.178 ml.min.-1.100 g-1 during reperfusion. When blood flow to the stomach was gradually returned to normal after ischemia by increasing celiac artery pressure by 10 mmHg every 10 min, the mucosal blood loss was reduced to 0.013 ml.min.-1.100 g-1. If the stomach was vascularly perfused with low PO2 (34 mmHg) blood for 1 h after ischemia before being returned to normal arterial perfusion, the mucosal blood loss was also reduced to 0.063 ml.min.-1.100 g-1. When the stomach was made hypoxemic for 1 h rather than ischemic by perfusing the vasculature with low PO2 (29 mmHg) blood then reperfused with normoxic blood, there was very little mucosal bleeding (0.014 ml.min.-1.100 g-1). The data indicate that gastric mucosal bleeding after ischemia is reduced if the tissue is returned slowly to a normal PO2. These findings support the concept that reperfusion injury is due largely to the production of oxygen radicals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Gastric injury induced by hemorrhage, local ischemia, and oxygen radical generation.

Gastric mucosal injury caused by local intra-arterial generation of oxygen-derived free radicals was compared with gastric injury caused by 30 min of hemorrhage-induced ischemia (systemic pressure of 30 mmHg) or local ischemia (celiac artery pressure of 30 mmHg). The index of injury was the loss of 51Cr-labeled red cells across the gastric mucosa. Generation of oxygen radicals in the celiac artery caused a rapid increase in mucosal blood loss during the period of radical generation (0.029 +/- 0.013 ml X min-1 X 100 g-1, mean +/- SE), and this loss was maintained after radical production ceased (0.041 +/- 0.018 ml X min-1 X 100 g-1). Local ischemia produced similar mucosal injury; however, this occurred after reperfusion of the stomach (0.038 +/- 0.006 ml X min-1 X 100 g-1) and not during the ischemic episode (0.001 +/- 0.0003 ml X min-1 X 100 g-1). Hemorrhage-induced ischemia produced a threefold greater mucosal blood loss (0.133 +/- 0.048 ml X min-1 X 100 g-1) than local ischemia. The results of this study indicate that oxygen radicals generated enzymatically in the blood supply to the stomach cause mucosal bleeding of similar magnitude to that observed after local ischemia and that gastric ischemia induced by systemic hypotension produces more severe gastric injury than the same level of local hypotension.

Animals↗