[The association of age and tracer clearance determined radionuclide cisternography].

We aimed to study tracer kinetics in radioisotope (RI) cisternography. For this purpose, we analyzed the RI images of 36 individuals in whom absence of cerebrospinal fluid (CSF) leakage was confirmed. For the semiquantitative assessment of tracer clearance, the geometric mean of the RI count in the anterior and posterior images was obtained for the entire head as well as for the whole spinal axis. After correcting for the radioactive decay of the tracer, tracer clearance was expressed as a ratio of the count in the range of the whole CSF space at different time points to that at the time of tracer delivery. Tracer clearance from the CSF space was not related to the degree of cranial transport of the tracer in 1 hour, but was significantly related with the age of the patients. At 24 hours after the injection, tracer clearance was significantly faster in the younger patients (Group I: age < 40 years) than in the older patients (Group II: age > or = 40 years). The cranial transport of the tracer appeared to be rapid in group I; however, the difference between these 2 groups was not significant. These results indicate that age should be taken in account while establishing the reference values for tracer kinetics in normal individuals.

[A study of operator's hand and finger exposure dose reduction during angiographic procedures].

The number of examinations using interventional radiology (IVR) has increased recently. Because of the more advanced and more complex procedures for IVR, longer treatment time is required. Therefore, it is important to determine exposure doses. We measured operator exposure dose during IVR using a thermoluminescence dosimeter. The results revealed the dose equivalent to the operator's hands and fingers to be higher than that of other parts, although the effective dose for the operator was low. Moreover, we looked into the factors that affected exposure dose to the operator's fingers, and examined ways to reduce the dose. In regard to the exposed dose to the operator's fingers, dose reduction was possible as a result of a geometric arrangement of the fluoroscopic unit, the radiation field size, using a radiation protective device and deliberation to exposure dose reduction of the operator. It is possible to carry out IVR more safely using the method of exposure dose reduction to the operator's fingers.

[Estimation of operator dose by dose area product meter].

Because of the more advanced and more complex procedures in interventional radiology (IVR), longer treatment times have become necessary. Therefore, it is important to determine the exposure doses received by operators and patients. Operator doses arising from the use of X-rays are mainly due to scattered radiation. The purpose of this study was to assess the feasibility of estimating operator dose by dose area product (DAP), which shows the total X-ray output from the collimator. DAP showed a strong correlation with the space dose from the fundamental examination. In clinical practice, we measured the exposure doses of the neck, left shoulder, left hand, and right finger using a thermoluminescence dosimeter (TLD). These then were compared with the DAP. The results indicated that the dose equivalents (H70 microm) of the neck and left shoulder were strongly correlated with DAP (r=0.85, 0.86), whereas the H70 microm of the left hand and right finger were less closely correlated (r=0.40, 0.48). In comparison with the fluoroscopic time, the dose equivalents showed a better correlation with DAP in all the evaluated parts. The effective doses for the operator were strongly correlated with DAP (r=0.87). When measurements are not available, dose equivalents and operator effective doses can be estimated by the DAP, as indicated by the strong correlations recognized in this study.

[Semi-quantiative RI cisternographic patterns in patients with chronic headache: a resemblance to those of intracranial hypotension syndrome].

Semi-quantitative radionuclide cisternography was performed to evaluate CSF leakage for patients with long-lasting headache and/or neck pain or refractory dizziness which appeared to be related to posture as well as patients with spontaneous intracranial hypotension (SIH). Radioactivity in the whole CSF space was counted and was plotted against time. SIH cases showed rapid decrease of radioactivity in the CSF space. Chronic headache patients were divided into Group I (rapid decrease of activity similarly to those in patients with SIH, to less than 80% at 5h and 40% at 24h), Group II (gradual decrease to less than 40% at 24h), and Group III (activity remained more than 80% at 5h and 40% at 24h). Of 16 patients in Group I, epidural blood patch was attempted in 14, and improvement of symptoms was obtained in 10. In 3 patients who underwent post-treatment RI study, tracer kinetics was normalized. These findings may indicate that some of patients with chronic headache actually have CSF leakage that can be treated with epidural blood patch.

Jugular compression and radionuclide cisternographic patterns in patients with chronic headache.

OBJECTIVE: We investigated the value of the jugular compression test (JCT) in screening patients with chronic headache attributable to persistent cerebrospinal fluid (CSF) leakage. METHODS: Clinical records of 35 consecutive patients who underwent both 111In-diethylenetriamine pentaacetic acid radioisotope (RI) cisternography and JCT were retrospectively analyzed. RESULTS: A strong correlation was seen between JCT and RI cisternographic findings. Most patients who reported a feeling of fullness in the ear, hearing loss or headache during JCT had positive findings on RI cisternograms indicative of CSF leakage. In contrast, no RI study abnormalities were seen in patients reporting no symptoms in JCT. CONCLUSIONS: Among patients complaining of refractory headache and other miscellaneous symptoms, JCT may represent a simple, economic, and reliable technique in the screening of candidates for RI cisternography to evaluate CSF leakage. A subgroup of patients with chronic headache may have persistent CSF leakage.

[Radionuclide cisternography for patients suspected of having intracranial hypotension].

We evaluated radionuclide cisternography for the diagnosis of intracranial hypotension in terms of the rate of appearance of abnormal findings in 23 patients, their correlation with therapy, and the most suitable scanning method and timing for visualization of leakage. During the first hour after injection, dynamic lumbar images or consecutively repeated whole-body images were acquired. Whole body images then were acquired at 1, 5, and 24 hours. Until 5 hours after injection, patients were kept in bed resting. Visualization of the leakage (direct finding) and that of the bladder (indirect finding) were observed in 78.3% (18/23) and 60.9% (14/23), respectively. Leakage was visualized most frequently at 5 hours after injection. There were three cases in which the leakage was only visualized at 24 hours. Therefore, there must be cases that show intermittent CSF leakage. To avoid overlooking these cases, a 24-hour whole-body image is also important. The appropriate procedure of radionuclide cisternography is very important to detect CSF leakage, and our procedure proved to be more effective for detecting the abnormal findings.

[Consideration of the newly standardized interventional reference point].

The interventional reference point is standardized by the International Electrotechnical Commission (IEC), and is adapted to adult cardiovascular studies. We examined the precision of the indicated incident dose at the interventional reference point. As a fundamental examination, we compared entrance phantom dose and incident dose at the interventional reference point. We also compared the entrance skin dose of patients with incident dose at the interventional reference point and evaluated the possibility of clinical application. Results showed that the incident dose at the interventional reference point indicated an underestimation of 0.77 times to an overestimation of 2.2 times when representing entrance surface dose. In clinical application, the incident dose at the interventional reference point calculated from the dose area product tended to overestimate by about 1.17 times the entrance skin dose measured by thermoluminescence dosimeter (TLD). Furthermore, the evaluation varied according to the angles of the C-arm of the x-ray system. A interventional reference point is a useful standard for simple, real-time dose measurement by the indirect method. It is important to understand the characteristics of the indicated incident dose at the interventional reference point in clinical use.