technetium-tc-99m-exametazime and Hypotension--Orthostatic

Takayasu arteritis is a chronic inflammatory angiopathy involving the cerebral arteries. We performed upright and supine 99Tcm-HMPAO brain single photon emission tomography (SPET) to investigate the cerebral perfusion pattern in eight patients with Takayasu arteritis, and we compared the results with those acquired using 123I-IMP and acetazolamide in six patients. SPET images were evaluated visually and semi-quantitatively. Hypoperfusion was visually detected in all eight patients during the provocative upright test with 99Tcm-HMPAO, and in three of six tested using acetazolamide and 123I-IMP. Semiquantitative analysis revealed that the mean cortical-to-cerebellar ratio in the upright position was significantly changed compared to that in the supine position in the right frontal area (from 0.86 +/- 0.07 to 0.91 +/- 0.09; P < 0.05). Change was also seen in the left frontal area (from 0.85 +/- 0.08 to 0.91 +/- 0.08; P < 0.05). No significant change was seen in other cortical areas with the upright test or in any areas with the acetazolamide test. We postulate that reduced arterial compliance may cause frontal postural hypoperfusion in patients with Takayasu arteritis due to poor functioning of autoregulation and arterial stenosis or occlusion. We conclude that the provocative upright test with 99Tcm-HMPAO brain SPET can detect abnormal patterns of cerebral perfusion in patients with Takayasu arteritis that might be missed by brain SPET using 123I-IMP and acetazolamide.

Topics: Acetazolamide; Adolescent; Adult; Aged; Blood Pressure; Brain; Cerebellum; Cerebral Arteries; Cerebral Cortex; Diuretics; Epinephrine; Female; Humans; Hypotension, Orthostatic; Male; Middle Aged; Radiographic Image Interpretation, Computer-Assisted; Radiopharmaceuticals; Takayasu Arteritis; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Double injection method using brain perfusion 99mTc-HMPAO SPECT is popular one for evaluating stress scintigraphy. For appropriate evaluation of this method 555 MBq (15 mCi) of 99mTc-HMPAO was injected twice in sequence at the resting state. The first and second SPECT images were obtained 5 min after each injection. Twenty-five ROIs of 8 x 8 pixels were placed on in various regions of the first images, and calculate each counts (C1). Then the counts of the same region of the second scan were calculated (C2). One hundred and fifty ROIs/6 patients were examined. We derived the linear relationship as C2 = 1.66 x C1 + 106 (r = 0.97), where C1 and C2 represents counts of the first scan, and second scan, respectively. This results suggests that the counts of the second scan is derived from the counts of the first scan without second scanning if they are obtained in the same condition. When we applied this method to stress scintigraphy, it may be useful for evaluating the regional brain perfusion changes before and after loading instead of using subtraction technique.

Topics: Aged; Aged, 80 and over; Brain; Cerebrovascular Circulation; Female; Humans; Hypotension, Orthostatic; Injections, Intravenous; Male; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

The psychiatric manifestations of three patients with systemic lupus erythematosus (SLE) and neuropathic dysautonomic processes are described. All patients had a severe form of SLE with neurological, renal, articular, pulmonary or haematological manifestations. All three have two types of psychiatric manifestations: (1) a chronic and progressive depression and (2) a complex dissociative disorder during the acute episodes of postural hypotension. A provocative test with SPECT with 99mTc-HmPAO to be done during the episode of orthostatic hypotension may contribute to clinical assessment of complex changes in cerebral regional perfusion.

Topics: Adolescent; Autoimmune Diseases of the Nervous System; Autonomic Nervous System Diseases; Brain; Cerebrovascular Circulation; Depression; Dissociative Disorders; Female; Humans; Hypotension, Orthostatic; Lupus Erythematosus, Systemic; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Young Adult

To clarify the relationship between abnormalities in cerebral blood flow (CBF) and in blood pressure regulation, we performed 99mTc-HMPAO brain SPECT in association with measurement of plasma norepinephrine and blood pressure in both the upright and supine positions.. We studied six patients with orthostatic hypotension and six normal patients. No patient had any significant stenosis of the carotid arteries on echocardiography-Doppler ultrasound and no abnormalities on brain MRI or CT. Changes in systolic blood pressure were monitored during the upright test, and 8-ml blood samples were taken at baseline and at 1 and 5 min after the upright position.. Systolic blood pressure decreased by a mean of 38 +/- 10 and 9 +/- 3 mmHg in the orthostatic hypotension and normal groups, respectively. Compared with baseline values, plasma norepinephrine levels at 1 and 5 min after the upright test did not increase in the orthostatic hypotension group but did increase significantly in the normal group. In the orthostatic hypotension group, 99mTc-HMPAO brain SPECT showed postural cerebral hypoperfusion in the bilateral frontal areas, of which the mean count ratio of the frontal-to-cerebellar area between the upright and supine positions significantly changed from 0.871 +/- 0.029 to 0.942 +/- 0.067 and from 0.881 +/- 0.035 to 0.954 +/- 0.073 in the right and left areas, respectively. No postural change in CBF was evident in other areas in the orthostatic hypotension group. In the normal group, there were no such changes in CBF, blood pressure and plasma norepinephrine levels during the upright test.. Postural cerebral hypoperfusion in the frontal areas in the orthostatic hypotension group might relate to maladaptation of the vascular response during the upright test.

Topics: Blood Pressure; Brain; Case-Control Studies; Cerebrovascular Circulation; Female; Humans; Hypotension, Orthostatic; Male; Middle Aged; Norepinephrine; Organotechnetium Compounds; Oximes; Posture; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon

A 57-yr-old woman had frequent syncope when rising from a seated position. Her blood pressure fell from 140/80 mmHg to 60-70/40 mmHg while changing positions. Iodine-123-metaiodobenzylguanidine ([123I]MIBG) did not accumulate in the heart, whereas 201Tl-Cl (201Tl) did. Raise-up 99mTc-hexamethyl-propyleneamine oxime (99mTc-HMPAO) brain SPECT revealed decreased activity in the bilateral frontal areas, and subsequent supine 99mTc-HMPAO brain SPECT revealed filling in these areas, indicating that the cerebral blood flow (CBF) was transiently decreased in the frontal areas more than others in a standing position. The plasma norepinephrine (NE) level of this patient was normal during supine rest, but when she stood up, failure to increase the plasma level of NE uncovered a sympathetic nervous dysfunction. The CBF abnormality in patients with orthostatic hypotension may be due to a "functional" hemodynamic mechanism that induces orthostatic stress. This patient had transient hypoperfusion in the frontal areas when standing, without organic cerebral arterial stenosis. Only CBF in the frontal areas revealed relative hypoperfusion. These regions might be highly susceptible to a change in blood flow. The causes of orthostatic hypotension of this patient were autonomic failure with a disturbance of the sympathetic nerve endings, which was revealed by 99mTc-HMPAO brain SPECT and cardiac [123l]MIBG imaging.

Topics: 3-Iodobenzylguanidine; Autonomic Nervous System; Brain; Cerebrovascular Circulation; Female; Heart; Humans; Hypotension, Orthostatic; Iodine Radioisotopes; Iodobenzenes; Middle Aged; Organotechnetium Compounds; Oximes; Technetium Tc 99m Exametazime; Thallium Radioisotopes; Tilt-Table Test; Tomography, Emission-Computed, Single-Photon

To determine whether regional cerebral blood flow (rCBF) would change on standing in patients with idiopathic orthostatic hypotension (IOH), Tc-99m HMPAO SPECT studies were performed during postural testing in five patients with IOH. After 10 minutes of quiet rest on a bed, the patients arose quickly and, at the same time, the radiotracer was injected intravenously. SPECT data were obtained with a ring-type SPECT scanner. Another dose of Tc-99m HMPAO was injected with the subjects in the supine position, and SPECT was performed again. Image subtraction was used to evaluate the change in rCBF caused by postural testing. In all patients, the authors observed a decrease of rCBF ni the frontal cortex and basal ganglia. This preliminary study suggests that changes in rCBF occur in patients with IOH on standing, and Tc-99m HMPAO SPECT performed during postural testing may have an important role in evaluating these changes.

Topics: Brain; Cerebrovascular Circulation; Female; Humans; Hypotension, Orthostatic; Male; Middle Aged; Organotechnetium Compounds; Oximes; Posture; Subtraction Technique; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon