18F-FDG PET/CT findings in a case of a semantic variant of primary progressive aphasia.

UNLABELLED: Progressive speech and language disorders are commonly referred to as primary progressive aphasia (PPA), which is a clinical syndrome eroding both speech and language. Functional imaging may reveal the cause of this disorder even if structural imaging is absent. Fluorine-18- fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) allows the assessment of neuronal activity by semi-quantitatively measuring glucose metabolism in the brain. In medical literature, (18)F-FDG PET/CT studies show hypometabolic areas in different regions of the brain which are special clues for differentiating the subgroups of PPA. CONCLUSION: This case was reported to demonstrate the characteristic (18)F-FDG PET CT findings for a semantic variant of PPA.

Evaluation of variability of phase indices of the left ventricle in the course of time.

OBJECTIVE: Since the effect of time on phase indices is still unclear, the aim of the study was to evaluate the variability of phase indices of the left ventricle which were derived from stress and rest single-photon emission computed tomography (SPECT) imaging acquired at early and late times. METHODS: One hundred twenty-one patients (72 men, 49 women) were included into the study. All stress and rest gated myocardial perfusion imaging (gMPI) acquisitions were acquired at two different time points as early in 15 ± 5 min and late in 45 ± 5 min. The peak of the phase histogram (PP), the standard deviation of the phase distribution (SDPH), the width of the band (BPH), and the symmetry (histogram skewness, HS) and peakedness of the phase histogram (histogram kurtosis, HK) which are the parameters for assessing left ventricular systolic dyssynchrony were calculated in all stress and rest SPECT images acquired twice. RESULTS: The phase indices derived from the late rest scans were smaller than those of the early rest scans but, the differences were not significant. When considering the comparisons of phase indices derived from two different time points after stress, PP showed a tendency to decrease (from 160.8 ± 18.3 to 152.5 ± 17.3; p < 0.001) over time but SDPH (from 20.2 ± 10.6 to 22.4 ± 12.2; p = 0.018) and BPH (from 61.5 ± 36.0 to 66.3 ± 37.3; p = 0.045) tended to increase over time. When the post-stress and the resting dyssynchrony parameters derived at two different time points were compared to each other; PP decreased at early and late times approximately 12 and 9 %, respectively, SDPH increased at early and late times approximately 28.5 and 14 %, respectively, and BPH increased at early and late times approximately 23 and 12 %, respectively. CONCLUSIONS: In resting conditions, phase indices of the left ventricle, and therefore, the phase histogram tend to remain constant over time but, in conditions after exercise, the phase histogram tend to be long and narrow due to changes in phase indices and it shows tendency to return to resting conditions in time. Therefore, it appears that postexercise acquisition times should be standardized if we want to compare the phase indices results of the studies in the literature.

Altered biodistribution of FDG in patients with type-2 diabetes mellitus.

OBJECTIVE: Positron emission tomography-computed tomography (PET-CT) imaging of patients with diabetes can be problematic because elevated glucose levels may cause competitive inhibition of [F-18]-2-deoxy-2-fluoro-D-glucose (FDG) uptake in different tissues. Therefore, the aim of the study was to evaluate the biodistribution of FDG in patients with type-2 diabetes mellitus. METHODS: Two hundred forty patients were retrospectively enrolled to the study. Study population was divided into three subgroups, named as the normal (group 1), the insulin (group 2) and the oral anti-diabetic (group 3). Unenhanced low-dose CT and PET emission data were acquired from the mid-thigh to the vertex of the skull. FDG uptakes in different organs were evaluated qualitatively or semi-quantitatively. RESULTS: In the diabetic groups, diffuse FDG uptake of the colon was increased (p > 0.001) but segmental FDG uptake was decreased (p > 0.001). Intestinal FDG uptake was detected in 20 % of the study population and only 3 % of these uptakes were in diffuse pattern. Segmental FDG uptake in the bowel was increased significantly in the groups of patients with diabetes (p = 0.002). Maximum standardized uptake values of the liver in the groups 1, 2, and 3 were 2.66 ± 0.6, 3.25 ± 0.9 and 3.16 ± 0.8, respectively, and the difference between the groups was not statistically significant (p = 0.083). Cardiac FDG uptake was decreased significantly in the groups of patients with diabetes (p < 0.001). CONCLUSIONS: According to our results, whole body biodistribution of FDG uptake seems to be changed in patients with type-2 diabetes who were using insulin or oral antidiabetic drugs. Although the use of oral antidiabetic drugs was known to change the biodistribution of FDG, insulin use also seems to change FDG uptake in different organs of diabetic patients.

Can single cIMT measurement during echocardiography affect further investigation decision for coronary artery disease?

OBJECTIVE: This study was aimed to evaluate whether there is any potential role of the measurement of the carotid intima-media thickness (cIMT) in patients with suspected coronary artery disease (CAD) during the echocardiography session on decision-making to refer patients for further diagnostic evaluation such as gated myocardial perfusion imaging (gMPI). METHODS: cIMT of 199 consecutive patients was measured during the echocardiography session and all patients underwent gMPI. According to gMPI results, patients were divided into two groups as CAD and normal groups and according to cIMT measurements patients were divided into four subgroups. RESULTS: Although, there was a good correlation between the age and cIMT values of the patients (r=0.546, p<0.001), the correlation between the summed stress scores and the age of the patients was very weak (r=0.142, p=0.045) and the correlation between the summed stress scores and the cIMT values was very weak (r=0.107, p=0.131). The cIMT measurements of the CAD group (0.74±0.17 mm) were significantly higher than those of the normal group (0.67±0.16 mm) (p=0.012), but after the age correction, the significance between the cIMT measurements of the CAD and the normal groups was not found (p=0.131). Besides, the relationship between the categorical cIMT values of both the CAD and the normal groups was insignificant (p=0.059) and the correlation between the increasing cIMT values and the presence of detectable CAD was also very weak (r=0.187, p=0.08). CONCLUSION: cIMT can predict occurrence of cardiovascular events in subjects, but single cIMT measurement during echocardiographic examination does not seem to have potential role on decision making for further investigation in patients with suspected CAD.

Phase analysis in patients with reversible perfusion defects and normal coronary arteries at angiography.

OBJECTIVE: A count-based new technique from gated myocardial perfusion single-photon emission tomography (gMPS) was developed to allow the phase analysis providing information about the left ventricular (LV) regional discordance in contractility which is a measure of LV dyssynchrony. Since the phase analysis provides data for evaluating the dyssynchronous LV contraction, it has an important role in diagnosis and management of patients with left ventricular dysfunction. The aim of the study was to assess the presence of left ventricular dyssynchrony in patients with reversible perfusion defects on gMPS scans and normal or near normal coronary arteries at angiography. METHODS: 32 patients (19 men, 59 %) with reversible mild perfusion defects on gMPS and normal coronary angiogram were retrospectively enrolled in the study. The peak of the phase histogram, the standard deviation of the phase distribution (PSD), the width of the band (PHB), and the symmetry and peakedness of the phase histogram, which are the assessment parameters for the LV dyssynchrony, were calculated from gMPS scans of patients by means of the phase analysis. RESULTS: Although, five quantitative variables are derived from the phase analysis of gMPS, PSD and PHB are two quantitative indices to assess LV global mechanical dyssynchrony and measurements of PSD (men 24.96 ± 7.31, women 24.26 ± 10.07) and PHB (men 70.1 ± 13.99, women 71.0 ± 30.4) were significantly higher than the those reported in the literature (p < 0.001). No significant differences in gMPS phase analysis indices were found between both sexes except kurtosis. CONCLUSION: As a conclusion, this study provides the phase analysis to detect LV mechanical dyssynchrony as new evidence supporting the concept that an abnormal scintigraphy finding, rather than being false-positive, may be an early marker of vasomotion changes associated with occult atherosclerosis in patients with normal coronary angiography findings.

The effect of about one third craniectomy on the cerebrospinal fluid flow rate as estimated by radionuclide cisternography in normal rabbits.

Since, the effect of a large cranial defect on the cerebrospinal fluid (CSF) flow rate is still not clear, this study was designed to evaluate the effect of craniectomy in rabbits by using a radionuclide technique, under in vivo physiologic conditions. Eleven male New Zealand white rabbits were examined. After the injection of technetium-99m-diethylene-triaminepenta-acetic acid into the fourth ventricle of each rabbit, dynamic acquisition for 60 min (1 min per frame) was performed pre-op followed by about one third craniectomy to each animal. Injection of the radiopharmaceutical and the imaging steps were repeated at 24 h (post-op 24 h) and at 7 days (post-op 7 d) after craniectomy. The region of interest (ROI) was drawn around the injection site and a time activity curve was generated. Slopes of each curve were calculated to detect the flow rate of the radiopharmaceutical from the injection site during 60 min. Besides, the count decreased ratio (ROIcounts of the last frame ROI counts of the first frame X100) was calculated. Our results showed that the pre-op values of the slope of the time-activity curve and the count decreased ratio were decreased 24 h and 7 d post-op but statistically significant was only the difference between the above values pre-op and 7 d post-op (P=0.04, P=0.01 respectively). In conclusion, the data of the present study indicate that the CSF flow rate in rabbits decreased 7 d after one third craniectomy.

Massive inguinoscrotal herniation of the bladder with ureter: incidental demonstration on bone scan.

Inguinoscrotal herniation of the bladder is a rare clinical entity. The condition is often diagnosed incidentally or during the course of surgical repair of inguinal hernias. In a smaller number of cases, bladder hernia can be seen during nuclear medicine studies. We report a rare case of massive inguinoscrotal bladder herniation with ureter, causing urinary stasis on bone scintigraphy.

A physiologic approach to decreasing upward creep of the heart during myocardial perfusion imaging.

UNLABELLED: When body position changes from erect to supine, the effect of gravity on the organs also changes and is a possible underlying mechanism for upward creep of the heart during SPECT acquisitions. We hypothesized that if we provide enough time for the organs to settle after a positional change, the range of this vertical motion causing reconstruction artifacts can be decreased. Our aim was to evaluate the effect that a 5-min bed rest on the imaging table before both rest and stress SPECT acquisitions would have on upward creep of the heart. METHODS: Before both stress and rest SPECT acquisitions, the first 101 consecutive patients (group A) had a 5-min bed rest and the remaining 99 patients (group B) did not have any bed rest after they were positioned on the imaging table. Upward creep was detected by comparing the distance between the lower edge of the image and the lowest part of the heart silhouette on the last projection image of detector 2 and the first projection image of detector 1. RESULTS: Upward creep was found in 53% (54/101) and 55% (56/101) of patients in group A and in 89% (88/99) and 86% (85/99) of patients in group B in stress and rest SPECT studies, respectively. Upward creep of the heart was decreased prominently in group A, and this decrease was statistically significant (p < 0.001). CONCLUSION: We conclude that before SPECT acquisition, at least a 5-min bed rest on the imaging table significantly decreases vertical motion of the heart.

Radiolabeled L-lysine for tumor imaging.

RATIONALE AND OBJECTIVES: The aims of this study were to label the versatile amino acid l-lysine with (99m)Tc using 2,3-dimercapto-succinic acid (DMSA) as a chelator, and to assess its tumor imaging feasibility under in vivo and in vitro conditions, and finally to determine the subcellular biodistribution of this radiopharmaceutical. MATERIALS AND METHODS: DMSA-l-lysine was chemically synthesized and labeled with sodium pertechnetate. Nuclear magnetic resonance (NMR) and mass spectral analysis of DMSA-l-lysine were conducted. Radiochemical purity was determined by thin-layer chromatography (TLC) and paper chromatography. Cellular uptake, competition and subcellular localization studies were performed in rat breast cancer cells (13762). In vivo studies of planar imaging and biodistribution studies were performed on female Fischer 344 rats. Medical Internal Radiation Dose (MIRD) dosimetry estimates were calculated. RESULTS: Radiochemical purity (determined by radio-TLC and high-performance liquid chromatography) of these compounds was >95%. (99m)Tc-DMSA-l-lysine showed good uptake in in vitro cell culture assays and uptake was reduced in competition studies. (99m)Tc-DMSA-l-lysine accumulates in the nucleus as much as in the cytoplasm and it was also shown that accumulation of the (99m)Tc-DMSA-l-lysine in the nucleus increases as a function of a time. There was an increase in tumor-to-blood and tumor-to-muscle count density ratios. Tumor/background ratios were 5.75 at 1 hour and 6.87 at 2 hours. In vivo tissue distribution studies revealed that radiation dosimetry of blood-forming organs were within radiation dose limits. CONCLUSION: DMSA-l-lysine kits can be labeled with (99m)Tc easily and efficiently, with high radiochemical purity and cost-effectiveness. In vitro cellular uptake and scintigraphic imaging studies demonstrated the pharmacokinetic distribution and feasibility of using (99m)Tc-DMSA-l-lysine for tumor imaging.

Scintigraphic imaging of endothelium-dependent vasodilation in the forearm: a preliminary report.

BACKGROUND: The diagnosis of endothelial dysfunction has been gaining clinical importance, but although endothelial function testing is available in the research setting, no technique yet exists that is simple, safe, reproducible and easily performed as a clinical screening method. The aim of this study was to design a new, scintigraphic method of imaging the flow-mediated dilation in the forearm, which represents the functional characteristic of endothelial dysfunction. METHODS AND RESULTS: The study group comprised 118 subjects in whom left forearm ischemia was induced by inflating a sphygmomanometer cuff to supra systolic pressure for 4.5 min. Later, dynamic acquisition (2 s frame/min) was initiated after the injection of technetium-99m methoxy-isobutyl isonitril into the dorsal pedal veins. Equivalent regions of interest were drawn on both arms to detect total activity counts during 1 min and the perfusion ratios (left arm/right arm) were calculated. The left arm counts (22,203.3+/-12,372.7) were significantly higher than the right arm counts (9,980.9+/-5,931.9) (p<0.001). A significant decrease in perfusion ratios was noted in the hypertension and hypercholesterolemia groups. An increase in the number of risk factors caused an insignificant decrease in perfusion ratio (p=0.346). CONCLUSION: Non-invasive evaluation of endothelium-dependent vasodilation by semiquantitative scintigraphic method using radioactive perfusion tracer provided promising results.