RESUMEN
We investigated the possible correlation between functional and anatomical imaging techniques and clinical exams in patients with Alzheimer's and vascular dementia. We examined 24 patients affected with dementia, 16 of them with Alzheimer's disease. 7 with multiinfarct and 1 with mixed dementia. All patients were submitted to clinical, morphological (MRI, CT) and functional (SPECT, cerebral flowmetry) studies. The severity of hypoperfusion revealed by SPECT was highly correlated with cognitive impairment in Alzheimer's dementia patients. The abnormal perfusion was mostly bilateral, in the temporal-parietal region, and involved the frontal regions only in the most severe cases. CT and especially MRI showed aspecific cortical and subcortical atrophy, most evident in the medial temporal region. In the patients with multiinfarct dementia, the hypoperfused cortical regions revealed by SPECT were sometimes related to vascular lesions proved at MRI and CT. In the patients with multiinfarct dementia, MRI showed more or less apparent white matter lesions referrable to ischemic insult, besides cortical and subcortical atrophy. MRI allows a differential diagnosis between these two cerebral pathologic conditions of aging. Cerebral flowmetry by Xenon 133 inhalation showed reduced cerebral blood flow in both dementia types. In Alzheimer patients, regional flow was reduced especially in the posterior parietal regions. In multiinfarct dementia patients, flow was more diffusely reduced and asymmetrical. Brain function imaging appears to yield useful information for the differential diagnosis in the most common dementia syndromes. Since the neuropathologic data from brain biopsy are rarely available, clinical and instrumental findings must be integrated for diagnostic and pathogenetic insights of the diseases causing cognitive impairment.
Asunto(s)
Enfermedad de Alzheimer/diagnóstico , Demencia por Múltiples Infartos/diagnóstico , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Tomografía Computarizada de Emisión de Fotón Único , Tomografía Computarizada por Rayos XRESUMEN
To date, Doppler US has been rarely used to diagnose chronic renal transplant rejection because of its low sensitivity. Nevertheless, all the results have been obtained from the analysis of flow-metric indices, mainly considering the diastolic phase of the Doppler waveform, e.g., the resistance index (RI) and the pulsatility index (PI). This study was aimed at investigating if Doppler diagnostic accuracy in renal transplant monitoring can be increased by studying the systolic phase, considering peak arterial systolic velocity (Vp), acceleration time (AT) and acceleration index (AI). Seventy-six renal transplant recipients were examined with color-Doppler and duplex Doppler US, which showed 47 well-functioning and 29 hypofunctioning kidneys. The diagnosis was confirmed with perfusion scintigraphy with 99mTc DTPA, biopsy and 6-month clinical-laboratory follow-up. The means of Vp, AI, AT and RI relative to the group of patients with normal renal function were compared with those in the group of patients with chronic rejection. Critical values were measured at the segmental arteries (Vp = 70 cm/s, AI = 7 m/s2, AT = 100 ms), at the interlobar arteries (Vp = 45 cm/s, AI = 4 m/s2, AT = 100 ms) and at the arcuate arteries (Vp = 35 cm/s, AI = 3 m/s2, AT = 100 ms). On the basis of these values, normal functioning transplants were differentiated from hypofunctioning ones. RIs were altered (> 0.75) in 8 of 17 chronic rejections and in 3 of 47 normal transplants, with 47.1% sensitivity and 93.6% specificity. The combination of RI with Vp and AI strongly increased both sensitivity (100%) and specificity (82.98%). Combined AI and RI exhibited 94.1% sensitivity and 89.3% specificity. In conclusion, the indices of the ascending systolic phase, in peripheral vascular samplings, are clearly more efficacious than RI alone and index combination exhibits the highest diagnostic accuracy.