Somatostatin-based radiopeptide therapy with [177Lu-DOTA]-TOC versus [90Y-DOTA]-TOC in neuroendocrine tumours.

PURPOSE: Somatostatin-based radiopeptide treatment is generally performed using the ß-emitting radionuclides (90)Y or (177)Lu. The present study aimed at comparing benefits and harms of both therapeutic approaches. METHODS: In a comparative cohort study, patients with advanced neuroendocrine tumours underwent repeated cycles of [(90)Y-DOTA]-TOC or [(177)Lu-DOTA]-TOC until progression of disease or permanent adverse events. Multivariable Cox regression and competing risks regression were employed to examine predictors of survival and adverse events for both treatment groups. RESULTS: Overall, 910 patients underwent 1,804 cycles of [(90)Y-DOTA]-TOC and 141 patients underwent 259 cycles of [(177)Lu-DOTA]-TOC. The median survival after [(177)Lu-DOTA]-TOC and after [(90)Y-DOTA]-TOC was comparable (45.5 months versus 35.9 months, hazard ratio 0.91, 95% confidence interval 0.63-1.30, p = 0.49). Subgroup analyses revealed a significantly longer survival for [(177)Lu-DOTA]-TOC over [(90)Y-DOTA]-TOC in patients with low tumour uptake, solitary lesions and extra-hepatic lesions. The rate of severe transient haematotoxicities was lower after [(177)Lu-DOTA]-TOC treatment (1.4 vs 10.1%, p = 0.001), while the rate of severe permanent renal toxicities was similar in both treatment groups (9.2 vs 7.8%, p = 0.32). CONCLUSION: The present results revealed no difference in median overall survival after [(177)Lu-DOTA]-TOC and [(90)Y-DOTA]-TOC. Furthermore, [(177)Lu-DOTA]-TOC was less haematotoxic than [(90)Y-DOTA]-TOC.

Targeted alpha-radionuclide therapy of functionally critically located gliomas with 213Bi-DOTA-[Thi8,Met(O2)11]-substance P: a pilot trial.

PURPOSE: Functionally critically located gliomas represent a challenging subgroup of intrinsic brain neoplasms. Standard therapeutic recommendations often cannot be applied, because radical treatment and preservation of neurological function are contrary goals. The successful targeting of gliomas with locally injected beta radiation-emitting (90)Y-DOTAGA-substance P has been shown previously. However, in critically located tumours, the mean tissue range of 5 mm of (90)Y may seriously damage adjacent brain areas. In contrast, the alpha radiation-emitting radionuclide (213)Bi with a mean tissue range of 81 microm may have a more favourable toxicity profile. Therefore, we evaluated locally injected (213)Bi-DOTA-substance P in patients with critically located gliomas as the primary therapeutic modality. METHODS: In a pilot study, we included five patients with critically located gliomas (WHO grades II-IV). After diagnosis by biopsy, (213)Bi-DOTA-substance P was locally injected, followed by serial SPECT/CT and MR imaging and blood sampling. Besides feasibility and toxicity, the functional outcome was evaluated. RESULTS: Targeted radiopeptide therapy using (213)Bi-DOTA-substance P was feasible and tolerated without additional neurological deficit. No local or systemic toxicity was observed. (213)Bi-DOTA-substance P showed high retention at the target site. MR imaging was suggestive of radiation-induced necrosis and demarcation of the tumours, which was validated by subsequent resection. CONCLUSION: This study provides proof of concept that targeted local radiotherapy using (213)Bi-DOTA-substance P is feasible and may represent an innovative and effective treatment for critically located gliomas. Primarily non-operable gliomas may become resectable with this treatment, thereby possibly improving the prognosis.

Different strategies to overcome the effect of carbimazole on high- and low-dose radioiodine therapy: results from continuous dose-effect models.

BACKGROUND: Until now, it remains elusive which strategy - antithyroid drug withdrawal or increased radioiodine target doses - should be preferred to avoid the detrimental effect of antithyroid drugs in high- and low-dose radioiodine therapy, respectively. METHODS: We explored the effects of carbimazole on the 1-year post-radioiodine success and hypothyroidism rates by continuous dose-effect models, whereas success was defined as elimination of hyperthyroidism. Euthyroidism rates with and without carbimazole were calculated by numerical integration of the area between success and hypothyroidism curves. Target dose amplification factors for equal chance of success with and without carbimazole were calculated using logistic regression. RESULTS: Two hundred and twenty-eight patients were included in this study. Radioiodine target doses between 33 and 839 Gy were applied. Overall, the euthyroidism rates were 16.5% and 64.8%, while the hypothyroidism rates were 37.6% and 14.8% in Graves' disease and toxic nodular goitre, respectively. The success rate with simultaneous carbimazole (median dose 15 mg day(-1); range 2.5-60 mg day(-1)) was reduced over the entire target dose range in Graves' disease and toxic nodular goitre. The areas between curves for euthyroidism without and with simultaneous carbimazole were 127 and 43 Gy in Graves' disease and 178 and 128 Gy in toxic nodular goitre. The estimated radioiodine target dose amplification factor was 5.5 for Graves' disease and 3.0 for toxic nodular goitre. CONCLUSIONS: Simultaneous carbimazole reduces the euthyroidism rate, the aim of low-dose radioiodine therapy, over the entire target dose range in both Graves' disease and toxic nodular goitre. Therefore, antithyroid drug discontinuation should be preferred in low-dose radioiodine therapy. Conversely, escalation of the target dose should be preferred in high-dose radioiodine therapy.

Impact of concomitant thyroid pathology on preoperative workup for primary hyperparathyroidism.

BACKGROUND: The former standard surgical treatment in patients with primary hyperparathyroidism (pHPT) has been bilateral cervical exploration. New localization techniques and the possibility of intraoperative measurement of intact parathormone (iPTH) permit a focused, minimally invasive parathyroidectomy (MIP). The introduction of MIP without complete neck exploration leads to the potential risk of missing thyroid pathology. The aim of the present study is to evaluate the value of MIP in respect to coexisting thyroid findings and their impact on preoperative workup for primary hyperparathyroidism. METHODS: This is a prospective study including 30 consecutive patients with pHPT (median age 65 years; 17 females, 13 males). In all patients preoperative localization was performed by ultrasonography and 99m Tc-MIBI scintigraphy- Intraoperative iPTH monitoring was routinely done. RESULTS: Ten patients (33%) had a concurrent thyroid finding requiring additional thyroid surgery, and two patients (7%) with negative localization results underwent bilateral neck exploration. Therefore, MIP was attempted in 18 (60%) patients. The conversion rate to a four gland exploration was 6% (1/18). The sensitivities of 99m Tc-MIBI scanning and ultrasonography were 83.3% and 76.6%, respectively. The respective accuracy rates were 83.3% and 76.6%. Of note, the combination of the two modalities did not improve the sensitivity and accuracy in our patient population. During a median follow-up of 40 months, none of the patients developed persistent or recurrent hypocalcaemia, resulting in a 100% cure rate. CONCLUSION: Coexisting thyroid pathology is relatively frequent in patients with pHPT in our region. Among patients having pHPT without any thyroid pathology, the adenoma localization is correct with either ultrasonography or 99m Tc-MIBI scintigraphy in the majority of cases. MIP with iPTH monitoring are highly successful in this group of patients and this operative technique should be the method of choice.

Silent ischemia after percutaneous transluminal coronary angioplasty: incidence and prognostic significance.

OBJECTIVES: The objective of this observational study was to assess the incidence and prognostic significance of silent ischemia after percutaneous transluminal coronary angioplasty. BACKGROUND: Apart from coronary angioplasty, prognosis of patients with silent ischemia is similar to that of patients with angina pectoris. However, similar data concerning silent ischemia associated with restenosis after coronary angioplasty are missing. METHODS: A consecutive series of 490 patients was investigated for asymptomatic ischemia on thallium-201 scintigraphy 6 months after successful coronary angioplasty. Repeat angiography was performed in a subgroup of patients with ischemia and repeat angioplasty was performed when clinically indicated. Patients were followed up for 2.2 +/- 0.8 years for cardiac events. RESULTS: Six months after coronary angioplasty, ischemia was present in 112 (28%) of 405 patients, and 60% of these 112 were asymptomatic. Ischemia was associated with significant stenosis in 97%; in contrast, results of exercise electrocardiography were negative in 74% of patients with scintigraphic ischemia and angiographic restenosis. The degree of restenosis was similar in patients with symptomatic or silent ischemia (80 +/- 16% vs. 81 +/- 21%). The long-term prognosis of patients with silent ischemia was remarkably similar to that of symptomatic patients. A worse outcome of symptomatic patients was found only if repeat coronary angioplasty for restenosis was considered a separate event (p < 0.01). Silent and symptomatic ischemia predicted an increased risk for recurrent ischemic events but not for death. CONCLUSIONS: Thus, absence of symptoms and negative findings on an exercise electrocardiogram may not reflect a good angioplasty result. In addition, silent ischemia due to restenosis after coronary angioplasty has a significant prognostic importance for recurrent symptomatic ischemic events that may be reduced by repeat angioplasty.

Important differences between short- and long-term hemodynamic effects of amiodarone in patients with chronic ischemic heart disease at rest and during ischemia-induced left ventricular dysfunction.

To assess and compare the hemodynamic profile of short-and long-term amiodarone administration in the same set of patients and to investigate hemodynamic mechanisms responsible for the antianginal effect of this drug, 10 patients with documented coronary artery disease and stable angina pectoris were studied. Simultaneous right heart catheterization and equilibrium radionuclide angiocardiography were performed at rest and during exercise before therapy (control), after a 5 minute intravenous infusion of 7.5 mg/kg of amiodarone and after 21.0 +/- 4.3 days of peroral therapy (10 days 800 mg/day, 7 days 400 mg/day and then 200 mg/day). After acute drug administration, ejection fraction, stroke index and systolic blood pressure decreased, whereas heart rate, left and right ventricular filling pressures and systemic vascular resistance increased. These effects were reversed after long-term therapy; all measured values returned to control levels except for heart rate, which decreased below the control value, and right atrial pressure, which remained slightly elevated. Amiodarone drug levels decreased from 4.8 +/- 1.8 after intravenous infusion to 1.2 +/- 0.6 mg/liter after long-term therapy. After adjustment for hemodynamic changes at rest, there were still significant reductions in heart rate, mean arterial pressure and rate-pressure product during exercise. It is concluded that the marked negative inotropic effect of amiodarone administered acutely in the dose applied calls for cautious use of this drug when administered intravenously. In contrast, long-term oral amiodarone therapy seems hemodynamically safe, even in patients with moderately depressed left ventricular function.(ABSTRACT TRUNCATED AT 250 WORDS)

Locoregional regulatory peptide receptor targeting with the diffusible somatostatin analogue 90Y-labeled DOTA0-D-Phe1-Tyr3-octreotide (DOTATOC): a pilot study in human gliomas.

Human gliomas, especially of low-grade type, have been shown to express high-affinity somatostatin receptor type 2 (J-C. Reubi et al., Am. J. Pathol, 134: 337-344, 1989). We enrolled seven low-grade and four anaplastic glioma patients in a pilot study using the diffusible peptidic vector 90Y-labeled DOTA0-D-Phe1-Tyr3-octreotide (DOTATOC) for receptor targeting. The radiopharmakon was locoregionally injected into a stereotactically inserted Port-a-cath. DOTATOC competes specifically with somatostatin binding to somatostatin receptor type 2 in the low nanomolar range as shown by a displacement curve of 125I-[Tyr3]-octreotide in tumor tissue sections. Diagnostic (111)In-labeled DOTATOC-scintigraphy following local injection displayed homogeneous to nodular intratumoral vector distribution. The cumulative activity of regionally injected peptide-bound 90Y amounted to 370-3300 MBq, which is equivalent to an effective dose range between 60 +/- 15 and 550 +/- 110 Gy. Activity was injected in one to four fractions according to tumor volumes; 1110 MBq of 90Y-labeled DOTATOC was the maximum activity per single injection. We obtained six disease stabilizations and shrinking of a cystic low-grade astrocytoma component. The only toxicity observed was secondary perifocal edema. The activity:dose ratio (MBq:Gy) represents a measure for the stability of peptide retention in receptor-positive tissue and might predict the clinical course. We conclude that SR-positive human gliomas, especially of low-grade type, can be successfully targeted by intratumoral injection of the metabolically stable small regulatory peptide DOTATOC.

Radioiodine uptake and thyroid hormone levels on or off simultaneous carbimazole medication: a prospective paired comparison.

AIM: To allow radioiodine (RAI) treatment in patients with need for anti-thyroid drug medication and low RAI uptakes we investigated the feasibility of discontinuing carbimazole for 3 days to enhance the RAI uptake without concurrent exacerbation of hyperthyroidism. METHODS: We prospectively investigated RAI dynamics and thyroid hormone concentration in 12 patients with low RAI uptake (<30%) under simultaneous carbimazole medication and 3 days after discontinuation. At both time points fT(4), T(3) and TSH were monitored. RESULTS: Discontinuation of carbimazole for 3 days led to a significant increase of RAI uptake in all patients. We found an enhancement up to 4.9-fold compared to the measurement on carbimazole. The mean RAI uptake increased from 15.2 +/- 4.4% to 50.1 +/- 15.5% (p<0.001). The intrapersonal radioiodine half-life increased from 4.2 +/- 1.6 days to 5.4 +/- 0.7 days (p = 0.13). Mean thyroid hormone concentration was not affected by the three day withdrawal of anti-thyroid drugs and no patient suffered from an aggravation of biochemical hyperthyroidism. CONCLUSION: A withdrawal of carbimazole for 3 days is long enough to provide sufficiently high RAI uptakes for RAI treatment in patients with low RAI uptakes and short enough to avoid the risk of exacerbation of hyperthyroidism.

Clinical value of a mucin-like carcinoma-associated antigen in monitoring breast cancer patients in comparison with CA 15-3.

A new tumour marker, mucin-like carcinoma-associated antigen (MCA), was evaluated in 176 breast cancer patients classified either as free of tumour (NED, n = 141) or as having metastases (PD, n = 35). During the 5 year follow-up, 842 measurements of MCA and 363 measurements of CA 15-3 were done. MCA levels were significantly increased in the PD group (P = 0.0001) but not in the NED group. The sensitivities of the MCA and the CA 15-3 assays were 84% and 78% and the specificities were 81% and 78%, respectively. The negative predictive value of 97% for MCA was significantly higher (P = 0.0001) than the 88% for CA 15-3. Thus the MCA enzyme immunoassay is at least equivalent to the CA 15-3 test and is recommended in the assessment of metastatic spread or tumour recurrence in breast cancer patients.

Cerebral blood flow and antihypertensive treatment with enalapril.

The intravenous 133Xenon method was used to measure regional cerebral blood flow (rCBF) in 20 patients with moderate hypertension. Regional cerebral blood flow under pretreatment, in the placebo period and after 8 weeks of enalapril treatment were compared. The rCBF values [(F1), and initial slope, (IS)] showed no statistical difference during the three periods in spite of significantly higher blood pressure values in the placebo period. It is concluded, that with enalapril good blood pressure control is achieved without any adverse effect on rCBF.

Combined acebutolol/nifedipine therapy in patients with chronic coronary artery disease: additional improvement of ischemia-induced left ventricular dysfunction.

To assess acute hemodynamic effects of combined oral nifedipine (10 mg) and acebutolol (100 mg), 21 patients with angiographically documented coronary artery disease and stable angina pectoris were studied (three groups of seven randomized patients). Simultaneous hemodynamic and equilibrium radionuclide ejection fraction measurements were performed at rest and during exercise before treatment, 1 hour after administration of nifedipine, acebutolol or a combination of the two and again 1 hour after combined nifedipine and acebutolol. At the same exercise level achieved without drugs, angina, subjectively scored by the patients, decreased significantly after nifedipine, acebutolol and a combination of the two in association with a significant improvement in left ventricular ejection fraction (p less than 0.01). There was an additive effect of both drugs on heart rate, systolic blood pressure and therefore the double product (p less than 0.01 each). The negative effects of acute beta receptor blockade on cardiac index, resting ejection fraction and total peripheral resistance were balanced by the vasodilatory action of nifedipine. In patients with borderline heart failure no untoward effects were seen after combined therapy. Thus, acute combined acebutolol/nifedipine therapy in patients with stable angina proved to be hemodynamically superior to therapy with either drug alone and safe even in patients with moderately depressed left ventricular function. This finding provides a basis for appropriately designed long-term studies.

Improved myocardial ischemia detection by combined physical and mental stress testing.

The hypothesis that addition of mental stress to physical exercise would modify the circulation response to stress and improve noninvasive detection of myocardial ischemia was tested in a randomized, crossover radionuclide angiocardiographic study. Compared with physical exercise or mental stress alone, combined stress led to higher heart rates and rate-pressure products in early stress stages, to more pronounced symptoms, and to a better discrimination of subjects with and without coronary artery disease by radionuclide angiography.

Crossed cerebellar diaschisis and brain tumor biochemistry studied with positron emission tomography, [18F]fluorodeoxyglucose and [11C]methionine.

Cerebral gliomas may cause a reduction of glucose metabolism in the cerebellum contralateral to the tumor side (crossed cerebellar diaschisis, CCD). We investigated whether CCD is related to tumor localization, histological grade, size and tumor biochemistry. Cerebellar glucose metabolism was measured in 44 glioma patients and 15 healthy subjects using positron emission tomography and [18F]fluorodeoxyglucose (FDG). CCD was determined by calculating an asymmetry index of cerebellar glucose metabolism. Further, the tumor uptake of FDG and [11C]methionine (MET) was also assessed, and was expressed as ratio of normalized tracer uptake in tumor over contralateral cortex (T/C). Frontal lobe tumors were associated with highest CCD values. For these tumors, CCD was higher in malignant (-11.8+/-9.9%) than in low-grade (-4.3+/-4.1%) gliomas (P=0.010). In addition, frontal lobe tumors showed increasing CCD values with increasing size. In tumors of the parietal or temporal lobe, CCD was less marked or absent. T/C ratios of tumor tracer uptake were higher in malignant than in low-grade gliomas, but were not correlated with CCD. Our data indicate that the magnitude of CCD is mainly determined by tumor localization and size, the latter being associated with tumor grade. These findings raise the question whether CCD provides a measure of expansion or progression particularly in low-grade tumors of the frontal lobe.

Radionuclide-labeled somatostatin analogues for diagnostic and therapeutic purposes in nonmedullary thyroid cancer.

Despite the fact that several recent studies report an expression of somatostatin receptors in nonmedullary thyroid cancer (non-MTC), there is still no consensus concerning the diagnostic and therapeutic usefulness of radionuclide-labeled somatostatin analogues in non-MTC. We present the results of 50 scintigraphic studies with (111)In-Pentetreotide ((111)In-P) in 48 patients with metastasizing non-MTC (n = 9 papillary, n = 9 follicular, n = 29 Hurthle cell, n = 1 insular carcinoma). The findings were compared with histology and with other imaging modalities. (111)In-P provided unequivocally positive results in 37 of 50 (74%) of the patients (27% in the 11 patients with current thyroglobulin levels <10 ng/mL and 85% in the patients with thyroglobulin >10 ng/mL). Histopathology demonstrated that maximal uptake was observed in Hurthle cell carcinoma (95% positive examinations if thyroglobulin exceeds 10 ng/mL). We also describe for the first time dosimetric and clinical data from the courses of 90Y-DOTATOC therapy in three patients with progressive, somatostatin-receptor-positive non-MTC (up to 9.3 GBq per 4 cycles). Tumor progression could not be stopped in any of the patients treated with 90Y-DOTATOC. We conclude that (111)In-P is a promising tool for whole-body diagnosis in nonradioiodine-accumulating non-MTC, especially in Hürthle cell cancer, and if 2-[18F]fluorodeoxyglucose-positron emission tomography (FDG-PET) is not available. Although the number of patients treated with 90Y-DOTATOC is still limited, our applied treatment protocol appears to be ineffective in metastasizing non-MTC.

Clinical significance of the new tumor marker MCA in the follow-up of patients with mammary carcinoma.

MCA is a mucin-like carcinoma-associated antigen which has been found in all breast cancer independent of histological type and degree of differentiation. A two-step solid-phase EIA was developed and the serum concentration of MCA was measured in 176 breast cancer patients after surgery. Using a cutoff of 11.0 U/ml the test showed a sensitivity of 77% and a specificity of 82% when compared to clinical status. The predictive value of this tumor marker was 72% for a positive diagnosis and 93% for a negative diagnosis. Based on these observations it is recommended that determination of MCA values take place 2 to 3 times in the first postoperative week in all women with surgically treated mammary carcinoma. These MCA values should then serve as reference for further determinations, which should be performed at each check-up. A subsequent increase in the MCA value should be considered as a first sign of metastasis.

Clinical value of a mucin-like carcinoma-associated antigen (MCA) in patients with carcinomas of the kidney and the urinary collecting system.

A new tumor marker, mucin-like carcinoma-associated antigen (MCA), was evaluated in thirty-four patients with renal cell carcinomas and forty patients with carcinomas of the urinary collecting system. In the first group, specificity was 95%, sensitivity 65%, the predictive value for positive diagnosis was 94%, and for negative diagnosis 72%. In the second group specificity was 83%, sensitivity 71%, predictive value for positive diagnosis was 63%, and for negative diagnosis 88%. Receiver operating characteristic curves indicated that the maximum amount of information was greater in patients of the first group than the second (0.379 vs. 0.332 bits). In the light of these data, the MCA test can be recommended for assessing metastatic spread in patients particularly with renal cell carcinomas.

The diagnostic value of mucinous carcinoma-associated antigen (MCA) tests in breast carcinomas.

MCA (Mucinous Carcinoma-Associated Antigen) levels of 176 breast carcinoma patients were tested postoperatively by serial determination. One hundred forty-one patients had non-progressive disease (PD-) while 35 were in the progressive phase (PD+); in the latter the diagnosis was confirmed by means of current diagnostic procedures. One hundred seventeen of the 141 PD-patients showed MCA levels below cutoff whereas 27 of the 35 PD+ cases showed high values. The difference in the incidence of elevated MCA levels between PD- and PD+ groups was statistically significant (p < 0.05). The overall diagnostic efficacy of MCA assays showed 77% sensitivity and 82% specificity.

Prevalence and extent of right ventricular dysfunction after myocardial infarction--relation to location and extent of infarction and left ventricular function.

In view of today's efforts to preserve myocardial function in acute myocardial infarction, the prevalence and extent of persistent right ventricular dysfunction was analysed in a prospective study of 127 patients admitted with a first myocardial infarction without thrombolysis. Right ventricular ejection fraction measured at hospital discharge by radionuclide angiocardiography was related to the location of infarction as judged electrocardiographically, its size as estimated enzymatically, and by the simultaneously measured left ventricular ejection fraction. Two opposite patterns of right and left ventricular function were observed in relation to the location of infarction: the right ventricular ejection fraction was significantly depressed in inferior, but not in anterior, infarction and the reverse was true for left ventricular ejection fraction (P less than 0.001 between infarct locations for both right ventricular ejection fraction and left ventricular ejection fraction). There were significant correlations between peak levels of creatine kinase and left ventricular ejection fraction for anterior (r = 0.76, P less than 0.001) and inferior (r = 0.57, P less than 0.001) infarction, while peak levels of creatine kinase and right ventricular ejection fraction correlated only in inferior infarction (r = 0.45, P less than 0.01). There was no overall correlation for left ventricular ejection fraction and right ventricular ejection fraction (r = 0.28, P NS), despite the fact that right ventricular ejection fraction was lower in patients with severely reduced left ventricular ejection fraction than in those with normal left ventricular function (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Successful diffusible brachytherapy (dBT) of a progressive low-grade astrocytoma using the locally injected peptidic vector and somatostatin analogue [90Y]-DOTA0-D-Phe1-Tyr3-octreotide (DOTATOC).

We present the therapeutic effect of diffusible brachytherapy (dBT), an innovative approach for the management of symptomatic low grade gliomas [1]. This protocol uses a radiolabelled small diffusible peptidic vector which is a somatostatin analogue to target somatostatin type 2 (sst-2) receptors. The stable radioconjugate [90Y]-DOTA0-D-Phe1-Tyr3-octreotide (DOTATOC) is repeatedly injected via catheters placed into the resection cavity or into tumour nodules. We report on the four year follow-up after initiation of dBT to treat progressive disease in a patient with a complex eleven year history of fibrillary low-grade astrocytoma. The radiopharmakon was not only locally injected into the resection cavity following debulking surgery, but also administered by slow infusion technique to target recurrent and infiltrative tumour zones in the subventricular region around the inferior and posterior horns. In conclusion, peptidic vector based dBT was found to be safe, of mild and transitory toxicity, and effective in long-term tumour control.

[Acetazolamide stimulation test in the preoperative assessment of cerebrovascular reserve capacity in unilateral carotid obstruction]. / Acetazolamid-Stimulationstest bei präoperativer Evaluation zerebrovaskulärer Kapazitätsreserve bei einseitiger Karotisobstruktion.

Using the 16-detector 133Xe-NaCl technique (Novo Cerebrograph) quantitative measurements of regional cerebral blood flow (rCBF) were performed in 13 patients with unilateral carotid obstruction before and after stimulation with 1 g acetazolamide. In all patients resting studies showed no significant difference in hemispheric perfusion and a 47% flow increase after acetazolamide on the side with normal carotid artery. On the obstructed side in 8 patients the hemispheric flow increased equally indicating a sufficient and adequate intracerebral collateral circulation and capacity. In 5 patients a significant redistribution of brain flow occurred with diminished increase on the occluded side. This flow pattern indicates an inadequate vasodilator response and insufficient collateral capacity. The rCBF stimulation test identifies patients with a restricted collateral capacity and these patients could benefit from a surgical treatment.