Postoperative Positron Emission Tomography Research Articles

Positron emission tomography after fetal transplantation in Huntington's disease

Huntington's disease (HD) is a progressive disorder with no known cure. We report two-year postoperative positron emission tomography (PET) data from 7 HD patients who underwent intrastriatal fetal transplantation. Patients showed widespread reductions in glucose uptake with no significant change over 2 years. Dopamine receptor binding was significantly reduced in HD striatum. D1 binding did not change significantly following transplantation, but there was a significant loss of D2 binding. These findings may reflect loss of graft viability and/or disease progression. There was no significant relationship between changes in PET and clinical function. In summary, there was no benefit from transplantation.

Positron emission tomography for the early postsurgical evaluation of pediatric brain tumors

The object was to study the value of postoperative positron emission tomography (PET) to assess the extension of brain tumor resection. Twenty children operated on for total resection of a glial tumor (18 low-grade, 2 anaplastic) presented a signal on postoperative magnetic resonance (MR) images raising the question of a possible tumor residue. PET was performed early ((18)F-Fluoro-deoxyglucose in 1, (11)C-methionine in 16, both in 3) to further characterize the nature of the abnormal MR signal in order to consider second-look surgery. An increased tracer uptake found in 14 children led to reoperation on 11 of them, confirming the tumor histologically. No (11)C-methionine uptake led to a conservative attitude in 6 children in whom MR imaging follow-up showed no tumor progression. The early postoperative PET, especially with (11)C-methionine, appears to be a valid basis for complementary therapeutic decisions, especially second-look surgery, in glial tumors for which a radical resection is a key factor for prognosis.

Improvement of oxygen metabolic reserve after extracranial-intracranial bypass surgery in patients with severe haemodynamic insufficiency.

The effectiveness of extracranial-intracranial arterial bypass (EC-IC bypass) surgery on impaired haemodynamic status was studied in 12 patients with reduced regional cerebral perfusion pressure (rCPP) and elevated regional oxygen extraction fraction (rOEF) in the area distal to the symptomatic arterial lesion. Postoperative positron emission tomography (PET) study demonstrated a statistically significant decrease of rOEF in the operated hemispheres with disappearance of the pre-operative interhemispheric rOEF difference. Regional cerebral blood flow (rCBF) and regional cerebral oxygen metabolism (rCMRO2) were also increased in the operated hemispheres with disappearance of the pre-operative interhemispheric differences. Regional CBF/regional cerebral blood volume (rCBV) ratios of the symptomatic hemispheres were increased after surgery, but were still lower than in the contralateral hemispheres. We conclude that EC-IC bypass surgery improves impaired cerebral oxygen metabolic reserve.

EC/IC bypass 後に対側あるいは posterior circulation に虚血再発作を生じた症例の検討

Between 1981 and 1990, superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis was performed on 43 patients who had steno-occlusion of the internal carotid or middle cerebral artery. All of these patients were followed for an average of 6.5 years (range, 0.5 to 10 years). A follow-up study showed that 7 of these cases had a recurrence of an attack on the contralateral side or in the posterior circulation, but not on the ipsilateral side. Two of them had re-attacks on the contralateral side of EC/IC bypass, and 5 re-attacks took place in the posterior circulation. The symptoms of re-attack ware: 3 cases of TIA (vertigo, nausea), and 4 cases of stroke. The times of re-attacks were: immediately following surgery, 1 case; within 2 weeks following surgery, 1 case; 6 months or more following surgery, 5 cases. Fifteen out of 43 cases had 16 steno-occlusive lesions other than the operative side on preoperative angiography. Six of the 7 re-attack cases had steno-occlusive lesions on the re-attack sides. Positron emission tomography (PET) was performed on 18 cases before and after STA-MCA anastomosis. Five of these cases had re-attacks; 2 were in the form of misery perfusion on the contralateral side prior to surgery, and the re-attacks following surgery occurred on the same side. Another 2 cases who had cerebellar ischemias after postoperative PET study showed increasing of OEF on the cerebellar hemisphere postoperatively compared with the preoperative PET study.In conclusion, bypass surgery is effective in preventing recurrence of ischemic symptoms on the operated side. But in cases with steno-occlusive lesions on the non-operated side, a follow-up study such as cerebral hemodynamics and metabolism is necessary for predicting the occurrence of the ischemic attack of that area following surgery.

Relation of change in wall motion and glucose metabolism after coronary artery bypass grafting. Assessment with positron emission tomography.

Regional myocardial glucose metabolism was assessed by positron emission tomography (PET) in stunned myocardium. PET perfusion and metabolic imaging using N-13 ammonia and F-18 deoxyglucose (FDG) was performed before and 5-7 weeks after coronary artery bypass grafting (CABG) in 23 patients with coronary artery disease. Of 22 asynergy segments showing increased FDG uptake preoperatively, the postoperative PET showed a decrease in FDG uptake in 16 segments (73%) and persistent uptake in 6 segments (27%). The improvement in asynergy was observed in all of the segments showing postoperative decrease in FDG uptake, while it was observed in only 50% of those with persistent FDG uptake (p less than 0.01). On the other hand, 4 of 5 segments showing a new FDG uptake postoperatively revealed deterioration of wall motion abnormality. These data suggest that an increase in exogenous glucose utilization may often persist in postischemic myocardium. Improvement in regional function seems to be associated with the improvement in metabolic abnormality after CABG.

Positron emission tomography using fluorine-18 deoxyglucose in evaluation of coronary artery bypass grafting

To assess the clinical value of positron emission tomography (PET) in the evaluation of coronary artery bypass grafting (CABG), PET perfusion and metabolic imaging using nitrogen-13 ammonia and fluorine-18 deoxyglucose (FDG) was performed before and 5 to 7 weeks after CABG in 22 patients with coronary artery disease. Postoperative improvement in hypoperfusion was observed more often in the metabolically active segments (62%) than in the inactive segments (27%) on the preoperative PET study (p < 0.05). Similarly, the postoperative lessening of wall motion abnormality was observed more often in the metabolically active segments (78%) than in the inactive segments (22%) (p < 0.001). Of 19 asynergic segments showing increased FDG uptake before operation, the postoperative PET revealed a decrease in FDG uptake in 13 (68%) and persistent uptake in 6 (32%). The improvement in asynergy was observed in all the segments that showed a postoperative decrease in FDG uptake, but in only 50% of those with persistent uptake (p < 0.01). On the other hand, 4 of 5 segments showing a new FDG uptake after operation revealed further wall motion abnormality. Furthermore, the segments metabolically active before operation were more likely to have patent grafts (95%) than the metabolically inactive segments (70%) (p < 0.05). Thus, preoperative metabolic imaging using PET appears to be useful for predicting the response to CABG. Improvement in metabolic derangement was associated with improvement in regional function after CABG.

Hemodynamic and metabolic effects of cerebral revascularization.

Pre- and postoperative positron emission tomography (PET) was performed in six patients undergoing extracranial to intracranial bypass procedures for the treatment of symptomatic extracranial carotid occlusion. The six patients were all men, aged 52 to 68 years. Their symptoms included transient ischemic attacks (five cases), amaurosis fugax (two cases), and completed stroke with good recovery (one case). Positron emission tomography was performed within 4 weeks prior to surgery and between 3 to 6 months postoperatively, using oxygen-15-labeled CO, O2, and CO2 and fluorine-18-labeled fluorodeoxyglucose. Cerebral blood flow (CBF), cerebral blood volume (CBV), cerebral metabolic rates for oxygen and glucose (CMRO2 and CMRGlu), and the oxygen extraction fraction (OEF) were measured in both hemispheres. Preoperatively, compared to five elderly control subjects, patients had increased CBV, a decreased CBF/CBV ratio, and decreased CMRO2, indicating reduced cerebral perfusion pressure and depressed oxygen metabolism. The CBF was decreased in only one patient who had bilateral carotid occlusions; the OEF, CMRGlu, and CMRO2/CMRGlu and CMRGlu/CBF ratios were not significantly different from control measurements. All bypasses were patent and all patients were asymptomatic following surgery. Postoperative PET revealed decreased CBV and an increased CBF/CBV ratio, indicating improved hemodynamic function and oxygen hypometabolism. This was associated with increased CMRO2 in two patients in whom the postoperative OEF was also increased. The CMRGlu and CMRGlu/CBF ratio were increased in five patients. Changes in CBF and the CMRO2/CMRGlu ratio were variable. One patient with preoperative progressive mental deterioration, documented by serial neuropsychological testing and decreasing CBF and CMRO2, had improved postoperative CBF and CMRO2 concomitant with improved neuropsychological functioning. It is concluded that symptomatic carotid occlusion is associated with altered hemodynamic function and oxygen hypometabolism. Cerebral revascularization results in decreased CBV, indicating improved hemodynamic reserve, but does not consistently improve oxygen metabolism.