Revista Espa?ola de Medicina Nuclear (English Edition)最新文献

Objective

The aim of this study was to analyze cerebral perfusion and glucose metabolism in patients with cognitive impairment using cerebral blood flow ^99mTc-HMPAO SPECT and ¹⁸F-FDG PET/CT scans.

Material and methods

Twenty-two patients with cognitive impairment were included: 4 subjective memory complaints (SMC), 8 amnestic mild cognitive impairment (MCI), 5 prodromic Alzheimer's disease (AD) and 5 AD. In each clinical group, ^99mTc-HMPAO SPECT and ¹⁸F-FDG PET/CT scans were performed.

Results

^99mTc-HMPAO SPECT showed regions of cerebral hypoperfusion in 15 patients and was normal in 7 of the 22 patients. ¹⁸F-FDG PET/CT scan showed cerebral regional hypometabolism in 19 patients and was normal in the other 3 patients. The distribution of abnormalities on ^99mTc-HMPAO SPECT and ¹⁸F-FDG PET/CT scans was similar in 9 patients (2 SMC, 2 amnestic MCI, 2 prodromic AD, and 3 AD). In 6 patients (1 amnestic MCI, 2 prodromic AD, and 3 AD), FDG hypometabolism was more extensive than the cerebral hypoperfusion. Four patients (1 SMC, 3 amnestic MCI) had an abnormal ¹⁸F-FDG PET/CT scan and normal ^99mTc-HMPAO SPECT. There were 3 patients (1 SMC, 2 amnestic MCI) with normal ^99mTc-HMPAO SPECT and ¹⁸F-FDG PET/CT scans.

Conclusion

^99mTc-HMPAO SPECT and ¹⁸F-FDG PET/CT scans showed cerebral hypoperfusion and hypometabolism in patients with cognitive impairment, even in patients with clinical diagnosis of SMC. In patients with a normal cerebral blood flow SPECT, brain glucose cerebral hypometabolism can be detected. In some patients, the extension of FDG hypometabolism is more pronounced than that corresponding to the hypoperfusion area.

Aim

To evaluate the usefulness of the ⁷⁵SeHCAT abdominal retention (AR) measurement in the early diagnosis of diarrhea syndrome (DS).

Methods

Thirty-seven patients with diarrhea syndrome within the first month of evolution were prospectively evaluated. The ⁷⁵Se-SeHCAT abdominal retention was measured 4 and 7 days post-administration of 0.01 mCi of ⁷⁵SeHCAT. The test was performed prior to treatment and at 3 months when the baseline study was positive. The test was considered positive if the RA was <25% at 4th and <10% on the 7th day. The patients were followed up at 3 months. Depending on the response, 3 groups were established: (a) complete response: normalization of stool frequency, (b) partial response, decrease of frequency and (c) no response.

Results

Group A: The AR of ⁷⁵Se-SEHCAT was normal in 21 patients. Six were diagnosed of colonic diverticulosis, 8 of irritable bowel syndrome, 1 of lymphocytic colitis, 1 of post-gastroenteritis syndrome, 1 of celiac disease and 1 of stenosis of the cardia. Four are still under study. Group B: The AR of ⁷⁵Se-SEHCAT decreased in 16 patients. All showed abnormal AR at day 7 and all but 1 at day 4. Following administration of cholestyramine resin, 8 (50%) presented partial response and 8 presented (50%) complete response. At 3 months, AR had increased at day 4 and 9 at day 7.

Conclusion

The measurement of ⁷⁵SEHCAT abdominal retention allows the early diagnosis of bile acid malabsorption in 43% of the patients with DS. Measurement at 7 days seems more accurate than that at 4 days.

We report the case of a 47-year-old woman with a history of non-Hodgkin's lymphoma. During the course of her disease, we performed various ¹⁸F-FDG PET/CT that identified several significant incidental findings. First, we incidentally identified a hypermetabolic nodule in the left thyroid lobe, whose final diagnosis showed differentiated thyroid carcinoma. Second, metabolic activity was visualized in the thymus secondary to ablative treatment with radioiodine. This uptake disappeared in subsequent studies. Several papers have reported thymic rebound following chemotherapy but we have found only one case report of ¹⁸F-FDG uptake after radioiodine treatment. On the other hand, this case is of interest because it supports the benefit of studying the hypermetabolic thyroid nodules incidentally detected on the PET/CT performed for other reasons.