technetium-tc-99m-exametazime and Hepatic-Encephalopathy

A patient with hepatic encephalopathy is described. An initial SPECT using Tc-99m HMPAO was performed to evaluate relative brain perfusion. The initial brain SPECT images revealed decreased perfusion in the left frontal temporal lobe region. A subsequent carotid Doppler study revealed left-sided carotid artery stenosis. After appropriate medical treatment for elevated NH3 levels and reversal of the patient's symptoms, repeat SPECT brain images showed a normal pattern of activity. The possible causes and significance for these image findings are discussed.

Topics: Adult; Brain; Carotid Stenosis; Female; Hepatic Encephalopathy; Humans; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Hyperventilation is frequently used to prevent or postpone the development of cerebral edema and intracranial hypertension in patients with fulminant hepatic failure (FHF). The influence of such therapy on regional cerebral blood flow (rCBF) remains, however, unknown. In this study the CBF-distribution pattern was determined within the first 12 hours after development of hepatic encephalopathy (HE) stage 4 before and during hyperventilation. Ten consecutive patients (median age 48 [range 33-57] years) with FHF and 9 healthy controls (median age 54 [24-58] years) had rCBF determined by single photon emission computed tomography (SPECT) using intravenous injection of 133Xenon. For determination of high resolution CBF pattern, the patients were also studied with 99mTc-hexa-methylpropyleneamine oxime (HMPAO) in the hyperventilation condition. There was no significant difference in the rCBF distribution pattern during normoventilation as compared with hyperventilation. The anterior to posterior (AP) ratio was significantly lower in patients as compared with healthy controls. After hepatic recovery and disappearance of HE, 3 patients had restored normal rCBF distribution pattern as compared with healthy controls. We conclude that in sedated patients with FHF, a relatively lower rCBF is found in the frontal regions and in the basal ganglia as compared with posterior regions. This rCBF-distribution pattern was not aggravated during hyperventilation. It is speculated that this change of rCBF in patients with FHF may render the frontal brain regions more susceptible to hypoxia. The relative frontal rCBF decrease was shown to be reversible with hepatic recovery and alleviation of HE.

Topics: Adult; Alcohol Drinking; Basal Ganglia; Brain; Cerebrovascular Circulation; Female; Frontal Lobe; Hepatic Encephalopathy; Humans; Hyperventilation; Male; Middle Aged; Regional Blood Flow; Respiration, Artificial; Survival Rate; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon; Xenon Radioisotopes

Topics: Aged; Brain; Cerebrovascular Circulation; Female; Hepatic Encephalopathy; Humans; Radiopharmaceuticals; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Topics: Hepatic Encephalopathy; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Radionuclide Imaging; Technetium Tc 99m Exametazime; Temporal Lobe