A comparison of Tc-99m HM-PAO and I-123 IMP cerebral SPECT images in Alzheimer's disease and multi-infarct dementia.

SPECT images of the brain can be obtained using either 123I labelled amines or 99mTc-hexamethylpropyleneamineoxime (HM-PAO). Both materials produce images which are blood flow dominated and so appear similar in normal subjects, although the respective mechanisms of uptake are not yet finally established. It seems likely, however, that the different mechanisms of uptake are responsible for recent reports of some differences seen in images obtained with the two types of agent in patients with cerebral pathology, mainly cerebrovascular disease. In this study, 12 demented patients, 6 with dementia of the Alzheimer type (DAT) and 6 with multi infarct dementia (MID), were imaged with 123I-isopropylamphetamine (IMP) and 99mTc-HM-PAO and the images compared. Significantly more lesions were seen with IMP than HM-PAO (P less than 0.02); out of a possible 120 sites, 41 lesions were seen with IMP compared to 28 with HM-PAO, 23 being seen with both agents. However, it is concluded that either agent can be used for the differential diagnosis of dementia, a task for which the new cerebral blood flow agents seem well suited

Brain imaging and treatment response in spasmodic torticollis.

A patient with spasms of the neck, occurring when he turned his head to the left, responded to treatment with benzhexol. Cerebral blood flow imaging demonstrated reduced uptake in the right corpus striatum compared with the left. The study demonstrates the presence of an abnormality in the basal ganglia; it also illustrates response to drug treatment. Cerebral blood flow imaging may be useful in the detection of basal ganglia abnormalities in spasmodic torticollis and assist in the selection of cases which should be targeted for treatment with drugs

Differential diagnosis in dementia using the cerebral blood flow agent 99mTc HM-PAO: a SPECT study.

One of the potential clinical uses of the new cerebral blood flow agent 99mTc-hexamethylpropyleneamineoxime (HM-PAO) is the investigation of dementia, in particular to differentiate between dementia of the Alzheimer type (DAT) and multiinfarct dementia (MID). In this study 27 patients, 17 with DAT and 10 with MID, and three normal volunteers were imaged both with single photon emission CT and magnetic resonance. The HM-PAO perfusion deficits were much more common in the DAT group than in the MID group, especially in the temporoparietooccipital (TPO) regions. The two groups of patients were found to be significantly different (p less than 0.02), as regards the frequency of occurrence of bilateral TPO perfusion deficits. Four of the 17 DAT patients did not have bilateral TPO deficits but these included the three least impaired patients as assessed by psychometric testing

Multimodal imaging in Alzheimer's disease. The relationship between MRI, SPECT, cognitive and pathological changes.

Patients with a clinical diagnosis of Alzheimer's disease were studied using MRI, SPECT, and psychometric tests. Significant correlations between focal perfusion deficits and focal cognitive deficits were found. Significant correlations between regional relaxation time of white matter and psychometric tests of diffuse and focal categories were also found. Pathological examination confirmed Alzheimer's disease as the only diagnosis