Increased cerebral blood flow in MELAS shown by Tc-99m HMPAO brain SPECT.

We report cerebral SPECT studies on two siblings with the syndrome of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS). Tc-99m HMPAO brain SPECT was performed 8, 19 and 30 days after a stroke-like episode in one case and 10 days after a stroke-like episode, 6 h after a partial seizure and as a follow-up study in the other. Increased blood flow was seen in both these patients with stroke-like episodes due to MELAS. The cause of the increased blood flow is uncertain, but it may be related to the decreased pH created by local increase in lactic acid.

Posterior 180 degrees 99mTc-dimercaptosuccinic acid renal SPECT.

UNLABELLED: As a result of a high percentage of hypoactive upper poles of kidneys in traditional 99mTc-dimercaptosuccinic acid (DMSA) SPECT, a prospective study was conducted using 180 degrees acquisition technique compared with 360 degrees to minimize tissue attenuation. METHODS: Anterior 180 degrees, posterior 180 degrees and 360 degrees renal SPECT images were obtained simultaneously using a dual-head camera. Forty-one subjects without renal disease and 16 subjects with 21 cortical defects were included in this study. The total counts of the raw data in the anterior 180 degrees, posterior 180 degrees and full 360 degrees were calculated. Small regions of interest were drawn over the cortex of the kidney on coronal and reoriented sagittal slices. Quantitative evaluation of regional activity was performed on the same frames in all three acquisition methods. RESULTS: Comparison of the total renal counts between the anterior and posterior 180 degrees data showed reduced counts in the anterior 180 degrees data collection (P < 0.01). Visual evaluation of the reconstructed images from anterior 180 degrees, posterior 180 degrees and full 360 degrees data collection showed the best image uniformity in the posterior 180 degrees image. The upper/lower pole ratio in the posterior 180 degrees renal SPECT images increased significantly in comparison to full 360 degrees renal SPECT images (P < 0.01) and anterior 180 degrees SPECT images (P < 0.01). The renal defects were more clearly visualized in the posterior 180 degrees renal SPECT images than the full 360 degrees renal SPECT images. The defect/normal cortex ratios in the posterior 180 degrees renal SPECT images were much lower than those from the full 360 degrees SPECT images (P < 0.01) and those from the anterior 180 degrees SPECT images (P < 0.01). CONCLUSION: The posterior 180 degrees acquisition technique can avoid the problem of hypoactive upper pole and can be less time consuming in 99mTc-DMSA SPECT images. It also provides superior lesion contrast in the clinical evaluation of patients with renal scarring.

Feasibility of simultaneous dual-isotope myocardial perfusion acquisition using a lower dose of sestamibi.

The feasibility of simultaneous dual-isotope myocardial perfusion imaging was assessed using a ca. 12 mCi dose of technetium-99m sestamibi (MIBI) and ca. 3 mCi thallium-201. Planar and single-photon emission tomographic (SPET) data from 40 patients (41 studies) imaged with both a single- and a dual-isotope protocol were analyzed. Rest injected 201T1 (pure-T1) images were acquired using 20% windows at 70 and 166 keV about 15 min after the 201T1 injection. Patients were then stressed, and at peak stress 99mTc-sestamibi was injected. About 30 min later 99mTc data were recorded with a 20% window center at 140 keV, and simultaneous 201T1 (dual-T1) data were recorded with a single 20% window centered at 80 keV. Total myocardial counts based on SPET data in the dual-T1 images were increased by 18.61% +/- 2.91% (SEM) (range: -12.8% to 84.1%) compared to pure-T1 images. Region of interest analysis revealed the greater increase in counts in the apical region and the least in the lateral wall. Pure T1 and dual-T1 images were visually evaluated for image quality (IQ) on a five-point scale (0 = unacceptable to 4 = excellent). Dual-T1 IQ was lower than that of pure-T1 in 61% of cases, and similar in 37% (12% of the pure-T1 and 41% of the dual-T1 images fell into the 0 and 1 categories). Thallium perfusion abnormalities were of similar extent in 70% of segments, less severe in 18%, and more severe in 12%. There was an inverse correlation with patient weight, such that patients weighing more than 180 lbs had substantially worse images than those below this cutoff value. While dual-tracer images are of lower quality, they are interpretable if the patient is not severely overweight.

Persistent fever in a patient with polycystic kidney and liver diseases and bilateral hip prostheses.

Persistent fever in a 60-yr-old man with polycystic kidney and liver diseases and bilateral hip prostheses was presented in this study. Multiple diagnostic tests failed to localize a source of infection. Subsequently, a combination of a 111In-oxine labeled WBC and 99mTc-sulfur colloid scans (and computer subtraction) demonstrated abnormally increased WBC activity in the left lobe of the liver, thus, diagnosis of an infected cyst (or cysts) was made. The patient responded to the treatment with antibiotics. This article discusses the clinical features of polycystic disease of the liver and kidneys. Infection in cysts are discussed as well as radiographic and scintigraphic investigations that can be used to diagnose and localize infection in a cyst.

Feasibility of Meckel's scan after RBC gastrointestinal bleeding study using in-vitro labeling technique.

The authors report a successful Meckel's scan performed 26 hours after a labeled RBC study using a commercial in-vitro labeling kit, UltraTag (Mallinckrodt Medical, Inc., St. Louis, MO). No abnormal alteration of Tc-99m distribution was observed as would be seen if an in-vivo RBC labeling technique was used. This case demonstrates that it is feasible to perform an in-vitro labeled RBC study for acute gastrointestinal bleeding in pediatric patients and to follow-up with a Meckel's scan if it is necessary for diagnostic confirmation.