Assessment of cerebral perfusion and cerebrovascular reserve in insulin-dependent diabetic patients without central neurological symptoms by means of 99mTc-HMPAO SPET with acetazolamide.

The detection of subclinical abnormalities in cerebral blood flow could be of great value in identifying diabetic patients at risk of stroke. The aim of this study was to assess the contribution of semiquantified post-acetazolamide technetium-99m hexamethylpropylene amine oxime single-photon emission tomography (99mTc-HMPAO SPET) in 15 diabetic patients with no clinical history of central neurological disease. After baseline 99mTc-HMPAO SPET, a second SPET scan was acquired after activation of the cerebrovascular reserve (CVR) with an injection of 1 g of acetazolamide (post-ACZ SPET). Semiquantitative analysis was made in 16 regions of interest (ROIs) drawn for each of the three supratentorial slices selected, and in two ROIs in the infratentorial slice. The CVR was calculated in each ROI by subtracting the decay-corrected baseline images from those obtained in the post-ACZ SPET and expressed as the percent increase in the average counts between the two scans. Baseline perfusion and CVR values in the study group were compared with the corresponding values in a control group. Of 750 cortical ROIs studied, 332 showed a decreased CVR (44.3%). The baseline perfusion SPET study showed hypoperfusion in 65 ROIs (8.6%) and hyperperfusion in 56 (7.4%). Of the 65 hypoperfused regions, 66.2% had a normal CVR and 33.8% had a decreased CVR, whereas of the 56 hyperperfused regions, 51.8% had a CVR within normal limits and 48.2% showed a decreased CVR. In conclusion, in comparison with baseline 99mTc-HMPAO SPET, the ACZ activation test provided additional information in the study of cerebrovascular impairment, and allowed characterisation of the subclinical abnormalities in the population studied. The technique may therefore prove useful in evaluating future preventive strategies for stroke in diabetic patients.

[Perfusion SPECT with (99m)Tc-HMPAO in type I diabetics with no background of central neurologic symptoms. A study of activation with acetazolamide]. / La SPECT de perfusión con HMPAO-(99m)Tc en los diabéticos tipo I sin antecedentes de clínica neurológica central. Un estudio de activación con acetazolamida.

OBJECTIVE: This study aimed to assess if activation with acetazolamide increases the diagnostic capacity of baseline SPECT with (99m)Tc-HMPAO in the study of brain perfusion in type I diabetic patients with no history of neurological symptoms. MATERIAL AND METHODS: A baseline SPECT was carried out in 11 diabetes mellitus type I patients with no neurological symptoms with 555 MBq of (99m)Tc-HMPAO; 1 g of acetazolamide was administered during the examination and a second SPECT was obtained 20' later with the same methodology used in the baseline SPECT. The images were visually analyzed. The post-acetazolamide studies were analyzed with (CBS) and without (WBS) baseline image subtraction and both methods were compared. RESULTS: The baseline SPECT showed 48 hypoperfused cortical areas. The post-acetazolamide SPECT analyzed without baseline image subtraction detected 14 new hypoperfused areas and those analyzed with it detected 26 areas. 69% of the baseline hypoperfused areas were hyporeactive in the WBS analysis and 54% in the CBS analysis. CONCLUSION: The perfusion SPECT with acetazolamide improves the diagnostic capacity of the baseline perfusion (99m)Tc-HMPAO SPECT, and makes it possible to classify the abnormalities as metabolic or vascular, with a preference for the post-acetazolamide CBS imaging analysis.

[Localization by bone SPET of osteoid osteoma in the vertebral lamina]. / Localización mediante SPET óseo de un osteoma osteoide en la lámina vertebral.

The combined use of bone SPET and CT was a good approach for diagnosing an osteoid osteoma of spine in a 16-year-old young woman with a history of several months of back pain. Pain was increased at night and relieved by aspirin intake. Plain films of the spine only revealed a scoliosis. Bone SPET demonstrated a focal increased activity in the left posterior elements of T12 vertebra. CT of this vertebra discovered a lytic lesion in the left lamina. An osteoid osteoma was removed by laminectomy.

[Postoperative uptake of Ga-67 in planar scintigraphy and SPECT after median sternotomy]. / Patrones de captación postquirúrgica del Ga67 tras esternotomía media en gammagrafía planar y SPECT

Surgical alterations after median sternotomy can difficult the interpretation of scintigraphic images with Ga67. To analize the use of Ga67 scintigraphy in this patology, we wanted to know the Ga67 distribution in patients who had suffered median sternotomy. We studied 8 patients in the first month after median sternotomy without infection complication and performed planar images and SPECT. Ga67 showed uptake in liver, spleen and bone. Sternal uptake was greater or lesser than liver uptake but always showed an homogeneous distribution. No mediastinum uptake was observed. Surgical wound showed Ga67 uptake during the first week after sternotomy. To know the <> distribution of Ga67 in patients after median sternotomy allows the scan interpretation when we suspect infectous complications.

Double-phase Tc-99m sestamibi scintigraphy in the preoperative location of lesions causing hyperparathyroidism.

Hyperparathyroidism (HPT) is one of the most prevalent endocrine diseases, for which the only effective treatment is surgery. The use of imaging techniques in the preoperative localization of the hyperfunctioning glands is the subject of controversy. The purpose of this paper is to assess the use of double-phase scintigraphy with Tc-99m sestamibi in the localization of lesions causing HPT. We used scintigraphy to preoperatively examine 41 patients, 31 of whom had primary HPT and 10 with secondary HPT. We acquired two anterior view planar images of the neck and chest 10 minutes and 3 hours after injection of Tc-99m sestamibi. Final diagnosis, determined with biopsy, was adenoma in 26 patients, 24 of whom had a positive scintigraphic study (sensitivity 92%), with only two false negative results. In the 14 cases of parathyroid hyperplasia, scintigraphy was also positive, and 62% (30/48) of the excised glands were identified by Tc-99m sestamibi. The radioisotope study was of particular interest in the six patients who previously had undergone surgery, since all the studies were positive; in two patients, additional diseased glands were located in the neck, and an ectopic adenoma was found in the remaining four patients. A fifth ectopic lesion was also sestamibi-positive and, in this case, the scintigraphic result was a direct indication for mediastinal surgery. There were no false positive results, even in patients with multinodular goiter. We conclude that, due to its high sensitivity and the ease with which it is performed, double-phase scintigraphy with Tc-99m sestamibi is the preferred technique for the preoperative localization of diseased glands in patients with HPT, especially in cases of parathyroid adenoma, including those with aberrant location. Its use is of particular interest in patients who previously have undergone surgery.