Evaluation of the effect of Royat thermal gas in arteriopathy of the legs using thallium-201 muscular scintigraphy

12 patients (group II) suffering from an arteriopathy of the lower limbs, stage II, were examined by thallium 201 muscular scanning. The aim of this study was to look for a possible muscular effect of Royat thermal gas injected subcutaneously. A preliminary study was conducted at rest, and consisted of recording the initial decay curve of thallium in the thighs and the study of the muscular fixation by different segments of the limbs, including the determination of the ratios of amounts fixed by the muscular and non-muscular zones. The results were compared with those obtained in 11 healthy subjects (group I) and no significant difference was noted between the two groups at rest. On the other hand, a considerable improvement of the fixation in the legs was observed after subcutaneous injection of thermal gas. The results are discussed in relation to the clinical and paraclinical data.     

Quantitative analysis of thallium-201 uptake and washout before and after transluminal coronary angioplasty

Transluminal coronary angioplasty has become an important therapeutic modality in the treatment of coronary artery disease. The effects of coronary angioplasty on regional myocardial perfusion have been reported in only a small series of patients, employing subjective analysis of thallium-201 perfusion scintigrams. Thus, we studied 61 patients with quantitative analysis of thallium-201 uptake and washout before and after undergoing angioplasty. Prior to angioplasty, there were 105 areas in 47 patients with abnormal thallium-201 uptake during exercise, with a mean uptake of 49 +/- 1.3%. The uptake of thallium-201 in these same areas increased to 71.3 +/- 1.9% post angioplasty (P less than 0.0001), and 68 (65%) of the areas showing abnormal uptake returned to normal. Abnormalities in washout of thallium-201 before angioplasty were seen more frequently than in uptake (150 vs 105 areas, P less than 0.05), with 8 patients having abnormal washout in the presence of totally normal uptake. Thallium-201 washout in the abnormal areas improved from 16 +/- 2.8 pre angioplasty to -23 +/- 1.8% post angioplasty (P less than 0.001). Normalization resulted in 6 of the 8 patients with exclusively washout abnormality. Residual abnormalities in uptake and/or washout were seen in 53% of the patients, usually in areas with prior myocardial infarction or supplied by a vessel with significant stenosis which did not undergo angioplasty. Improved thallium-201 uptake and washout corresponded to reductions in percent coronary area stenosis (89 +/- 1.0 to 36 +/- 2.0%, P less than 0.001) and transstenotic pressure gradient (42 +/- 3.0 to 9.0 +/- 2.0 mm Hg, P less than 0.001). Thus, quantitative analysis of thallium-201 uptake and washout provided objective evidence for improved myocardial perfusion after coronary angioplasty. Due to a fairly high prevalence of residual perfusion abnormalities after this procedure, optimal assessment of benefits requires quantitative comparison of thallium uptake and washout before and after coronary angioplasty.     

Exercise echocardiography versus thallium-201 SPECT for assessing patients before and after PTCA.

This study was designed (1) to assess the relationship between stress exercise echocardiography (echo) and 201-Tl single photon emission computed tomography (SPECT) applied simultaneously in 23 patients who were candidates to percutaneous transluminal coronary angioplasty (PTCA), (2) to assess the relationship between the development of exercise-induced wall motion abnormalities, transient perfusion defects and the severity of quantitatively assessed coronary stenoses and (3) to compare the functional improvement after PTCA by exercise echo and SPECT. Before PTCA there was an agreement of 78% between stress echo (new wall motion abnormalities) and SPECT (transient perfusion defects) results. All patients with a percentage diameter stenosis greater than 70% had a positive echo and SPECT, while they were both negative if the percentage diameter stenosis was less than 50%. In 19 patients re-studied 4 weeks after PTCA, an ischaemic response at stress echo was found in two of the 13 patients who had a positive stress echo test before PTCA, and SPECT was still positive in three of the 10 patients who had a positive SPECT study before PTCA. Echo and SPECT were concordant in 17/19 cases. It is concluded that exercise echo and 201-Tl SPECT are useful non-invasive tools for the functional assessment of patients before and after PTCA, and that they provide highly concordant results.     

Clinical value of thallium-201 myocardial scintigraphy with dipyridamole performed before and after aortocoronary bypass

In addition to preoperative coronary angiography, 63 patients undergoing coronary bypass surgery also had myocardial scintigraphy with dipyridamole 1 to 2 days before surgery, resting scintigraphy 10 after bypass and a repeat scintigraphy with dipyridamole 3 to 6 months later. The myocardium was divided into 5 segments. In each segment the perfusion was classified as: normal, presence of a reversible defect (redistribution), presence of a permanent defect (no redistribution). A comparison of pre-and postoperative scintigraphies led to the following conclusions. Three to six months after bypass, improved perfusion was observed in 65.6% os ischaemic segments, showing that surgery was very effective. On the other hand, the immediate postoperative control (10 days) only showed improved perfusion in 42.5% of the ischaemic segments: this interval was too short to appreciate the benefits of coronary bypass. There was a good correlation between the scintigraphic improvement after surgery and the reversibility of the zones of hypofixation of Thallium before surgery. When the defect was reversible, 80% of the revascularised segments were improved. Fifty-eight per cent of non-reversible defects before surgery were unchanged by the revascularisation procedure. However, the absence of redistribution during preoperative scintigraphy was not synonymous with definitive myocardial lesions and does not represent a contra-indication to coronary bypass surgery; in fact, improved perfusion was observed in 42% of these constant defects. The quality of recovery depends on the condition of the muscle: only segments with normal motion can be improved. Degradation of the clinical condition of patients was always related to aggravation(lack of improvement in 1 case) of scintigraphy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Early redistribution of thallium-201 after temporary ischemia

To define the time course of redistribution of thallium-201 (201Tl), ischemia was induced in seven pigs by temporary occlusion of the circumflex coronary artery. After 1 1/2 min of occlusion 201Tl and labeled microspheres were injected into the left atrium. Flow was re-established 4 min after occlusion. Prior to reflow, the relative activities of 201Tl and microspheres in the ischemic area were similar, but as early as 5 min after reflow the relative 201Tl activity was considerably higher than the relative microsphere activity and from 15 to 105 min after reflow, relative 201Tl activity (averabe 69% of that in normal myocardium) continued to be higher than relative microsphere activity (average 6% of normal). Myocardial arteriovenous differences for 201Tl were followed sequentially after 201Tl injection in normal dogs and in dogs with temporary coronary occlusions. The results suggested both loss of 201Tl from normal myocardium beginning 10 min after 201Tl injection and increased extraction of 201Tl from the blood pool immediately after release of a transient occlusion. Redistribution of 201Tl therefore begins very soon after relief of myocardial ischemia and even a short delay in initiating myocardial imaging may decrease the sensitivity of the technique for detecting transient ischemia.     

静息201 Tl,201 Tl再分布,Isoket-201 Tl再注射显像评价犬梗死心肌存活力的研究

目的比较201 Tl,201 Tl再分布,Isoket-201 Tl再注射显像评价犬梗死心肌存活力的差异.方法制成9只犬冠状动脉人工结扎模型,随机将9只犬分为三组,进行201 Tl,201 Tl再分布,Isoket-201 Tl再注射显像,并观察其病理学改变.结果Ⅰ、Ⅱ、Ⅲ组犬静息201 Tl显像的放射性分布得分分别为17.1±1.0,18.7±2.1,22.0±2.6;静息 201 Tl再分布显像的放射性分布得分分别为15.3±1.5,17.3±3.5,20.0±1.0;Isoket-201 Tl再注射显像的放射性分布得分分别为12.5±2.5, 14.3±1.2,17.7±2.5.且Isoket-201 Tl再注射显像在检测心肌存活力方面与病理学改变一致性良好.结论 Isoket-201 Tl再注射显像是评价缺血心肌存活力的较准确可靠的方法.     

Dipyridamole thallium-201 myocardial scintigraphy in coronary diagnosis; a comparison of methods with thallium-201 myocardial scintigraphy after ergometer stress

Two scintigraphic methods, resting dipyridamole and exercise thallium-201 myocardial perfusion imaging, to detect and localize coronary artery stenosis were compared in 32 patients suffering from coronary artery disease. The sensitivity of detecting a greater than 50% coronary stenosis was 94% for exercise thallium-201 perfusion imaging and 88% for dipyridamole thallium-201 perfusion imaging. The overall sensitivity and specificity of localizing a greater than 50% coronary stenosis by the two methods were also not significantly different. The results of the two scintigraphic methods were independent of the severity of coronary artery disease. Dipyridamole thallium-201 myocardial perfusion imaging provides a useful and safe alternative test for detecting and localizing coronary artery stenosis in patients unable to perform maximal exercise.     

Non-clostridial gas gangrene in the diabetic lower limb

Summary Three cases of non-clostridial gas gangrene in diabetic lower limbs are reported. This rare condition occurs only in diabetes with peripheral neuropathy and is invariably fatal unless treated surgically. The clinical picture is deceptive with a slow, but insidiously progressive course, and the late appearance of skin necrosis. Antibacterial therapy is ineffective in preventing death. A serious delay may be fostered by inconclusive bacteriological investigations. Urgent radical amputation is required to save the patient's life.     

Intracoronary thallium-201 scintigraphy after thrombolytic therapy for acute myocardial infarction compared with 10 and 100 day intravenous thallium-201 scintigraphy

Thallium-201 imaging has been utilized to estimate myocardial salvage after thrombolytic therapy for acute myocardial infarction. However, results from recent animal studies have suggested that as a result of reactive hyperemia and delayed necrosis, thallium-201 imaging may overestimate myocardial salvage. To determine whether early overestimation of salvage occurs in humans, intracoronary thallium-201 scans 1 hour after thrombolytic therapy were compared with intravenous thallium-201 scans obtained approximately 10 and 100 days after myocardial infarction in 29 patients. In 10 patients with angiographic evidence of coronary reperfusion, immediate improvement in thallium defects and no interim clinical events, there was no change in imaging in the follow-up studies. Of nine patients with coronary reperfusion but no initial improvement of perfusion defects, none showed worsening of defects in the follow-up images. Six of these patients demonstrated subsequent improvement at either 10 or 100 days after infarction. Seven of 10 patients with neither early evidence of reperfusion nor improvement in perfusion defects had improvement of infarct-related perfusion defects, and none showed worsening. In conclusion, serial scanning at 10 and 100 days after infarction in patients with no subsequent clinical events showed no worsening of the perfusion image compared with images obtained in acute studies. Therefore, there is no evidence that thallium-201 imaging performed early in patients with acute myocardial infarction overestimates improvement.     

Spontaneous changes in thallium-201 myocardial perfusion imaging after myocardial infarction

To examine regional myocardial perfusion after myocardial infarction, 26 patients underwent exercise electrocardiographic testing with thallium-201 myocardial perfusion imaging 3 weeks and 3 months after infarction. At 3 weeks, 9 of 26 patients (35%) had myocardial ischemia by exercise electrocardiographic testing, whereas 18 of 26 (69%) had ischemia by thallium-201 imaging. The thallium-201 scintigrams were scored by dividing each image, in 3 views, into 5 segments, using a 5-point scoring scheme. The exercise thallium-201 score was 44.3 ± 1.2 and increased to 47.3 ± 1.2 in the redistribution study (p < 0.001). Three months after infarction, although there was a significantly greater rate-pressure product which would predict a larger ischemic defect and a decrease in the stress thallium-201 score, the stress score was improved (48.3 ± 1.1, p < 0.001). The redistribution score was similar, that is, 48.9 ± 1.0. The improvement in thallium-201 myocardial perfusion was associated with a loss of stress-induced ischemia in 8 patients (30%). These results indicate that spontaneous improvements in thallium-201 myocardial perfusion imaging may occur after myocardial infarction.     

Myocardial kinetics of thallium-201 after stress in normal and perfusion-reduced canine myocardium

Despite the emerging use of quantitative computer programs for assessing myocardial thallium uptake and clearance after exercise, little is known about the kinetics of thallium after exercise stress. Accordingly, 11 mongrel dogs with experimental left anterior descending coronary stenoses were given thallium during norepinephrine infusion to simulate exercise. The infusion was discontinued and thallium activity was monitored regionally using miniature radiation detectors for 3 hours. Heart rate, arterial pressure and double product all increased significantly during norepinephrine infusion. The mean fractional myocardial thallium clearance was lower (0.47 +/- 0.03 [+/- standard error of the mean]) for the stenosis zone than for the no-stenosis zone (0.57 +/- 0.03) (p less than 0.0001). The stress blood flow ratio (stenosis/no-stenosis zone = 0.27 +/- 0.06) was significantly lower than the final thallium activity ratio (0.68 +/- 0.07) (p less than 0.001), consistent with thallium redistribution occurring over the 3-hour period. Myocardial thallium activity in the stenosis zone peaked in a mean of 2.2 minutes, then washed out biexponentially with a final decay constant of 0.0035 +/- 0.0005 min-1. Myocardial thallium activity in the no-stenosis zone peaked within 1 minute in all dogs, then washed out biexponentially, with a final decay constant of 0.0043 +/- 0.0003 (p less than 0.001 compared with stenosis zone). In conclusion, fractional clearance of thallium can differentiate myocardium distal to a coronary artery stenosis from that supplied by a normal coronary vessel.     

Relationship of thallium-201 defect and left ventricular function after dipyridamole infusion

Tl-201 imaging and first-pass radionuclide ventriculography (RNV) by 4 min infusion of 0.56 mg/kg dipyridamole were performed on 22 patients with coronary artery disease in order to know the relationship of myocardial perfusion and left ventricular function after dipyridamole-infusion, and thereby to define whether Tl-201 defect with dipyridamole could imply myocardial ischemia. Initial and delayed Tl-201 images were divided into anterior, apical, and infero-posterior segments, and segmental perfusion defects were categorized as reversible, fixed and no defect. RNV on the 30-degree right anterior oblique view was also divided into anterior, apical, and infero-posterior wall to be evaluated for regional wall motion by a 5 point score before and after dipyridamole. Changes in left ventricular ejection fraction (LVEF) with dipyridamole were also calculated. Normal responses of regional wall motion and LVEF to dipyridamole were established from the data of 14 normal subjects. Reversible defects were closely associated (69%) with an abnormal response of regional wall motion (score decrease of 1 or more after dipyridamole). Both fixed defects and no defects showed little association with abnormal response of regional wall motion. Moreover, 77% of the patients having reversible-defect segment showed an abnormal response of LVEF (reduction of 3% or more following dipyridamole). However, patients without reversible defect did not show an abnormal response to dipyridamole. These results suggest that dipyridamole-induced Tl-201 defects represent a myocardial ischemia which causes a reduction of ventricular function.     

Kinetics of thallium-201 in reperfused canine myocardium after coronary artery occlusion

To study the kinetics of thallium-201 in nonsalvaged acutely infarcted myocardium and salvaged myocardium, the tracer was administered after experimental left anterior descending coronary artery reperfusion 2 hours after occlusion. In 19 dogs, thallium activity was then monitored for 4 hours in the reperfused anterior wall and normal posterior wall using miniature cadmium telluride radiation detectors. After sacrifice, 13 of the dogs were found to have an infarcted anterior wall by triphenyltetrazolium-chloride staining. In these dogs, mean (+/- standard deviation) fractional 4 hour thallium clearance was 0.33 +/- 0.08 for the infarct zone and 0.15 +/- 0.06 for the normal control zone (p less than 0.001). When computer-modeled, the clearance curve from the infarct zone was biexponential. The second exponential clearance curve from the infarct zone began 19.1 +/- 3.2 minutes after tracer administration, and was indistinguishable from the monoexponential clearance curve from the normal control zone. Thallium clearance from the blood pool was triexponential, the final exponential clearance curve being indistinguishable from the normal control zone clearance curve. Six dogs were found to have a salvaged noninfarcted anterior wall by triphenyltetrazolium-chloride staining. In these dogs, mean fractional 4 hour thallium clearance was 0.20 +/- 0.07 for the reperfused zone, and 0.19 +/- 0.08 for the normal control zone (p = NS). When computer-modeled, clearance curves for the reperfused and control zones were monoexponential. The monoexponential clearance curve for the salvaged reperfused zone was indistinguishable from the monoexponential clearance curve for normal myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of eating on thallium-201 myocardial redistribution after myocardial ischemia

To determine whether eating a high-carbohydrate meal between initial and delayed postexercise thallium-201 (Tl-201) imaging affects detection of Tl-201 redistribution during exercise stress testing, 16 patients with stable angina performed 2 Tl-201 treadmill exercise stress tests within a 14-day interval. Immediately after initial postexercise imaging, patients either drank a commercially available instant breakfast preparation for the intervention test or drank an equivalent volume of water for the control test. Comparable exercise workloads were achieved by exercising patients to the same heart rate for both tests. The order of the 2 (intervention and control) tests were randomized. All patients had at least 1 region of Tl-201 myocardial redistribution on either their eating or control test scans, although only 7 of the 16 had positive treadmill exercise test responses. Forty-six regions showing Tl-201 myocardial redistribution were identified in all 144 regions examined. Significantly more of these regions were identified on control test scans than on eating test scans: 11 of 46 on both test scans, 6 of 46 only on eating test scans and 29 of 46 only on control scans (p less than 0.001). Consistent with results of the quantitative regional analysis, the percentage of Tl-201 clearance over 4 hours in the 46 Tl-201 myocardial redistribution regions was 39 +/- 8% for the eating tests and 29 +/- 8% for control tests (mean +/- standard deviation, p less than 0.003). In 4 patients diagnosis of transient ischemia would have been missed because their 14 Tl-201 myocardial redistribution regions were detected only on the control test scans.(ABSTRACT TRUNCATED AT 250 WORDS)     

Minimal redistribution of thallium-201 representing reversible ischemia after coronary bypass surgery: value of quantitative analysis of exercise thallium-201 SPECT]

We previously reported the value of minimal redistribution (MR) of thallium-201 in analyzing quantitative polar map analysis (QNT) which correlated well with metabolic activity on FDG-PET. To determine whether ischemic areas that have redistribution are truly reversible, we performed stress and 3-hr delayed thallium-201 SPECT imaging and radionuclide ventriculography (RNV) in 41 patients with coronary artery disease before and after coronary bypass surgery (CABG). Redistribution (RD) was categorized into 4 grades: complete RD (CR), incomplete RD (IR), MR and persistent defect (PD). MR was defined as the segment that showed > or = 2SD improvement in more than 1/3 of the area on QNT, but RD was not evident by visual analysis. 1. QNT identified MR in 30 of 56 segments (54%) where PD is noted by visual inspection. 2. The MR segments showed severer wall motion abnormality (wall motion score: 1.83 +/- 1.12) than did the IR or CR segments (0.99 +/- 1.04) (p < 0.01), but the wall motion was well preserved, compared to the PD segments (2.54 +/- 0.90) (p < 0.01). 3. The grade of RD was compared with improvement in regional perfusion and wall motion on RNV after CABG. Improvement in perfusion was observed in 62 of 77 IR or CR segments (81%) and in 17 of 30 MR segments (57%), but in only 3 of 26 PD segments (12%) (p < 0.01). 4. Similarly, improvement in wall motion was observed in 45 of 57 IR or CR segments (79%) and in 22 of 27 MR segments (81%), but in only 5 of 25 PD segments (20%) (p < 0.01). Thus, the MR segments should be considered reversible after CABG. We conclude that QNT of RD should be performed to detect RD which is slight, yet suggestive of viability.