Assessment of the half-life of cationic periodontal pocket irrigation.

BACKGROUND: The concentration and persisting time of antimicrobial agents in the periodontal pockets are important factors for their antimicrobial efficacy. Increased clearance time in the periodontal pocket is a significant criterion for the selection of intrapocket irrigants. The aim of this study was to estimate the clearance time of a cationic agent from the periodontal pocket. METHODS: Thallium-201(Tl-201) was chosen as a tracer to simulate the clearance of cationic substance because of its electrical activity. Twenty patients with periodontitis and probing depths 6 to 9 mm were included in this study. In each patient, 3 Mega Becquerel (MBq) of Tl-201 were inserted into the periodontal pocket. Dynamic imaging was performed and clearance of radioactivity was measured. RESULTS: Clearance of radioactivity was 67.1 ± 16.9, 83.1 ± 13.9, 90.4 ± 10.4, 93.39 ± 8.0% at 30, 60, 90 and 120 min, respectively. Half-life of wash-out was determined as 20.3 ± 10.2 min. CONCLUSION: The results of this study demonstrate that the half-life of the cationic solution applied subgingivally was approximately 20 min and labelling of oral irrigants with radiotracers may be used to determine their clearance in further research.

Diagnostic value of additional 18F-FDG PET/CT imaging using a vaginal catheter in patients with paravaginal malignant lesions.

BACKGROUND: In routine noncontrast-enhanced PET/computed tomography (CT) studies, the female pelvis is one of the most challenging anatomical regions to interpret. In surgically treated patients, it may be more difficult to determine the accurate location of paravaginal hypermetabolic lesions. In this study, the aim was to investigate the contribution of additional PET/CT imaging using a vaginal catheter in patients with pelvic malignant disease. METHODS: Forty-seven patients with pelvic malignancies were enrolled in this study. Following routine whole-body fluorine-18 fluorodeoxyglucose (F-FDG) PET/CT scanning, an additional pelvic scan was obtained after placement of a plastic catheter in the vaginal lumen (v-catheter). All suspected foci in vaginal and paravaginal areas were evaluated for both studies. The contribution of additional v-catheter imaging was determined visually by five experienced interpreters. RESULTS: Pathological F-FDG uptake in various vaginal and/or paravaginal locations was detected in 24 of 47 patients after conventional PET/CT imaging. In 10 of these 24 patients, anatomic relations within the uptake area could not be confidently described and v-catheter imaging provided a significant contribution in all 10 cases. In seven of these 10 sites examined, pathological F-FDG uptake was safely ruled out and three sites were confirmed to be malignant. In total, the final interpretation in 13 of 24 patients (54%) was modified by additional v-catheter imaging. The contribution rate of catheter imaging was 89% in treated patients and 33% in untreated patients with vaginal and/or paravaginal lesions on initial scans. CONCLUSIONS: Additional v-catheter imaging of pelvis may be of diagnostic value in the accurate anatomical definition of hypermetabolic lesions in the vaginal/paravaginal area on noncontrasted PET/CT studies.

Correlation of clinical, MRI and Tc-99m HMPAO SPECT findings in neuro-Behçet's disease.

UNLABELLED: Behçet's disease (BD) is a systemic disorder of unknown cause. In our study, we investigated the utility of Tc-99m HMPAO SPECT and MRI in patients with neuro-Beh,cet's disease (n-BD). PATIENTS AND METHODS: Twelve patients (two females, ten males; mean age 33 +/- 9.6 yr; age range 18-45 yr) with n-BD, fulfilling the criteria of the International Study Group for BD, were included in the study. MRI was performed according to a standard protocol with 1 or 1.5 T imagers. Brain SPECT data were obtained using a single head gamma camera after 555 MBq Tc-99m HMPAO injections. Following image reconstruction, regional cerebral perfusion was evaluated both visually and semi quantitatively. RESULTS: Neurological examination showed parenchymal brain involvement in 6 of 12 patients (50%). All 6 patients had white matter lesions on MRI, while only 5 of them showed perfusion defects on brain SPECT. Out of 6 patients (50%) without clinical signs of parenchymal brain involvement, 1 patient showed a pathological brain SPECT and 3 patients showed pathological MRI findings. Semiquantitative analysis of brain regions on SPECT study showed statistically significant hypoperfusion of biparietal regions. CONCLUSION: This study investigates the correlation between clinical, MRI and SPECT findings and it shows discrepancy between these findings in some cases. Brain SPECT may act as a complementary modality to increase the detection rate of affected regions in patients with n-BD.

Intracoronary versus intravenous injection of 99mTc-tetrofosmin: comparison of myocardial perfusion patterns and wall motion.

OBJECTIVES: The accuracy of viability and defect size detection by Tc-tetrofosmin has been discussed by several authors. The lower myocardial extraction fraction of the latter compared with Tc-sestamibi or Tl has often been emphasized. We hypothesized that the intracoronary (i.c.) injection of tracer activity, i.e. higher than that theoretically achievable in the case of intravenous (i.v.) administration, could demonstrate the clinical relevance of this finding intra-individually. In this study, myocardial perfusion images obtained after tracer injection down the infarct-related artery were compared with i.v. injection images in the same patients. The trial also provided us with the opportunity to compare the wall motion values calculated using conventional Tc-tetrofosmin gated single-photon emission computed tomography (SPECT) studies with those obtained using optimal target/background ratios after i.c. injection. METHODS: Fourteen patients with acute myocardial infarction, no history of previous cardiac events, single vessel disease and no visible collaterals in the coronary arteriogram were included in the study. Electrocardiogram gated SPECT was carried out separately after i.c. and i.v. injections of the tracer within 5-7 days following thrombolytic therapy. Myocardial perfusion patterns were compared by contingency table analysis after semi-quantitative visual scoring. Segmental wall motion was compared using quantified polar map data in a subset of patients (eight of 14) with normal to moderately hypoperfused myocardium supplied by the left coronary artery. RESULTS: Visual perfusion scores of both studies showed good concordance (kappa, 0.70), with complete agreement in 94 of 119 segments. Nearly all of the discordant segments (24 of 25) were mildly better scored in i.c. studies than in i.v. studies. The mean wall motion values calculated on polar maps of 78 segments for i.c. and i.v. studies were 8.4 +/- 1.2 mm and 8.2 +/- 1.3 mm (mean Delta wall motion=0.23 mm), respectively. High segmental wall motion correlation was observed (R=0.90; P<0.0001). CONCLUSION: It can be concluded that infarct-related myocardial perfusion scores obtained after i.c. and i.v. injections of Tc-tetrofosmin compare favourably, with a total agreement rate of 79%. However, the additional information obtained in 21% of the total number of myocardial segments by i.c. injection may indicate a mild underestimation of myocardial viability by i.v. injection. Conventional gated SPECT using i.v. Tc-tetrofosmin was demonstrated to be a reliable technique in the detection of true wall motion.

Comparison of gated planar Tc-99m tetrofosmin scintigraphy with radionuclide ventriculography and echocardiography in the evaluation of left ventricular wall motion.

Assessment of ventricular function is an important diagnostic and prognostic tool in coronary heart disease (CHD). The objective of this study was to compare radionuclide ventriculography (RVG), echocardiography (ECHO) and gated planar tetrofosmin myocardial scintigraphy (GPTF) in patients with CHD. Radionuclide ventriculography in left anterior oblique (LAO) and left lateral (LLT) projections was performed in 44 patients. Two days later, rest tetrofosmin perfusion tomoscintigraphy (SPECT) and rest GPTF in RVG identical parameters and projections were acquired. Within the two following days, the patients underwent two-dimensional ECHO. GPTF studies were processed and interpreted in original (NI-GPTF) and image inverted, RVG like form (I-GPTF). All visual interpretations were evaluated with a semi-quantitative scoring system. Quantitative analysis was performed on parametric images by means of segmental regions of interest. Linear regression and contingency analysis were carried out in overall analysis and on a segmental basis separately by accepting the RVG as the standard for the whole investigation. In overall cine-mode evaluation, NI-GPTF (r = 0.77, p < 0.001, complete agreement (CA) = 84%) was superior to I-GPTF (r = 0.73, p < 0.001, CA = 82%) and ECHO (r = 0.39, p < 0.001, CA = 78%), compared to RVG. On a segmental basis, NI-GPTF showed the best RVG-correlations except for inferoapical, mid-inferior, mid-anterior and anterobasal segments. In visual analysis of functional images, the best RVG-agreement was observed in I-GPTF (r = 0.72, p < 0.001, CA = 77%). On a segmental basis, I-GPTF showed the best RVG-correlations except for posterolateral, mid-inferior, mid-anterior and anterobasal segments. In overall quantitative evaluation, amplitude values in both I-GPTF (r = 0.76, p < 0.001) and NI-GPTF (r = 0.75, p < 0.001) studies were well correlated with RVG amplitude. I-GPTF gave the best RVG-correlation of phase (r = 0.59, p < 0.001). The mean phase and standard deviation RVG-correlations of I-GPTF were r = 0.92, p < 0.001 and r = 0.53, p < 0.001 respectively. In segmental quantification, amplitude values of all segments in I-GPTF were better RVG-correlated than in NI-GPTF. In conclusion, GPTF could be a time saving alternative to ECHO in the evaluation of wall motion by the nuclear medicine physician. Because of differing segmental RVG correlations, NI-GPTF and I-GPTF should be both interpreted to improve the diagnostic value of the method. Cine-mode and parametric image interpretations in GPTF studies should be done simultaneously since the former is more closely correlated to RVG.

Effect of O2-enriched breathing on myocardial uptake of 99mTc-sestamibi.

Oxygen (O(2)) inhalation after acute myocardial ischaemia has long been a part of standard therapy in cardiology. It has also been demonstrated that therapeutic hyperoxia diminishes myocardial stunning. The aim of this pilot study was to investigate whether the uptake kinetics of the myocardial perfusion agent technetium-99m sestamibi (MIBI) during O(2)-enriched breathing is modified in comparison with the kinetics observed under conventional rest imaging performed after injection during inhalation of room air. Nine patients scheduled for coronary intervention (CI) with a documented significant stenosis (> or =50%) of at least one epicardial coronary vessel and one patient with slow flow on coronary angiography were investigated. First, rest MIBI electrocardiogram-gated single-photon emission tomography (G-SPET) with 740 MBq was performed. Two days later, the tracer was injected following a 5-min period of 100% O(2)-supported (nasal catheter) breathing at rest (6 l/min) and a second G-SPET acquisition (O(2)+MIBI G-SPET) was carried out. Patients' medication was not withdrawn and was matched throughout the study. The mean elevation of arterial oxygen saturation achieved was 2.95%. No significant changes in arterial blood pressure or heart rate could be detected at any time during the procedure. Compared with the results of baseline G-SPET, on O(2)+MIBI G-SPET five patients scheduled for CI and the patient with slow flow showed increased tracer uptake in initially ischaemic regions without any alterations in other myocardial regions. In three of these five patients, post-CI imaging could be performed and showed increased tracer uptake in all additional areas detected previously by O(2)+MIBI imaging. In three patients, besides improvement in ischaemic regions, a mild reduction in tracer uptake was observed in myocardium that initially appeared normal. In one of these patients, thallium-201 rest-redistribution SPET was performed and showed an uptake pattern more similar to that seen on O(2)+MIBI images than that on baseline MIBI G-SPET. In one patient, no difference in tracer uptake was observed in pre- and post-CI studies. Improvement was detected in the wall thickening images of the O(2)+MIBI study in seven of the ten patients. Four of these patients showed improvement in the same regions after CI. In this pilot study, it was demonstrated that MIBI injection during O(2)-enriched breathing can be a useful technique for enhancing the detection of viable myocardial tissue. The possible mechanisms of altered tracer kinetics are discussed.