Quantitative Single-Photon Emission Computed Tomography/Computed Tomography for Glomerular Filtration Rate Measurement / 대한핵의학회잡지

PURPOSE: We propose a quantitative Tc-99m diethylenetriaminepentaacetic acid (DTPA) single-photon emission computed tomography/computed tomography (SPECT/CT) for glomerular filtration rate (GFR) measurement.METHODS: Quantitative SPECT/CT data obtained at 2–3 min post-Tc-99m DTPA injection (370 MBq) were used to determine % injected doses (%IDs) for individual kidneys. The reproducibility of %ID measurement was tested and compared with planar scintigraphy. Cr-51 ethylenediaminetetraacetic acid (EDTA) GFR was used as reference standard. Nine young volunteers, representing normal GFR, and ten older volunteers, reflecting impaired GFR, were enrolled. The established GFR equation derived from these volunteerswas applied to 19 renal tumor patients post-partial nephrectomy.RESULTS: At 2–3 min, %ID was most reproducible with the highest intraclass correlation (ICC) (0.9379) and lowest % coefficient of variation (CV) (6.5259%), which were more reliable than the ICC (0.9368) and %CV (6.7689%) of planar scintigraphy. Cr-51 EDTA GFR (93.16 ± 24.81 ml/min) correlated significantly with %ID (7.66 ± 2.15%, r = 0.7906, p = 0.0001), yielding an equation: Cr-51 EDTA GFR (ml/min) = (%ID × 9.1462) + 23.0653. This equation revealed significant decreases in total and nephrectomized kidney GFR (p = 0.0012 and p < 0.0001, respectively) from preoperative to 3-month postoperative measurements.CONCLUSIONS: Quantitative Tc-99m DTPA SPECT/CT produces reliable and clinically applicable %ID estimates that translate to the GFR of individual kidneys.

Reducing the Scan Time in Gastric Emptying Scintigraphy by Using Mathematical Models / 대한핵의학회잡지

PURPOSE: Gastric emptying scan (GES) is usually acquired up to 2 hours. Our study investigated whether a fraction of meal-retention in the stomach at 120 minutes (FR120) was predicted from the data measured for 90 minutes by using non-linear curve fitting. We aimed at saving the delayed imaging by utilizing mathematical models. MATERIALS AND METHODS: Ninety-six patients underwent GES immediately after taking a boiled egg with 74 MBq (2 mCi) Tc-99m DTPA. The patients were divided into Group I (T1/2 < or=90 min) and Group II (90 min< T1/2< or=120 min). Group I (n=51) had 21 men and 30 women, and Group II (n=45) 15 men and 30 women. There was no significant difference in age and sex between the two groups. Simple exponential, power exponential, and modified power exponential curves were acquired from the measured fraction of meal-retention at each time (0, 15, 30, 45, 60, 75, and 90 min) by non-linear curve fitting (MATLAB (R) 5.3) and another simple exponential fitting was performed on the fractions at late times (60, 75, and 90 min). A predicted FR120 was calculated from the acquired functional formulas. A correlation coefficient between the measured FR120 and the predicted FR120 was computed (MedCalc (R) 6.0). RESULTS: Correlation coefficients (r) between the measured FR120 and the predicted FR120 of each mathematical functions were as follows: simple exponential function (Group I: 0.8858, Group II: 0.5982, p< 0.0001), power exponential function (Group I: 0.8755, Group II: 0.6008, p< 0.0001), modified power exponential function (Group I: 0.8892, Group II: 0.5882, p< 0.0001), and simple exponential function at the late times (Group I: 0.9085, Group II: 0.6832, p< 0.0001). In all the fitting models, the predicted FR120 were significantly correlated with the measured FR120 in Group I but not in Group II. There was no statistically significant difference in correlation among the 4 mathematical models. CONCLUSION: In the cases with T1/2 < or=90 min, the predicted FR120 is significantly correlated with the measured FR120. Therefore, FR120 can be predicted from the data measured for 90 minutes by using non-linear curve fitting, saving the delayed imaging after 90 minutes when T1/2 < or=90 min is ascertained.

GFRs Measured by Gates' Method According to 5 Background Sites: Comparison with GFR Measured by I-125-Iothalamate Method / 대한핵의학회잡지

PURPOSE: The aim was to assess how the background site affects the Gates' glomerular filtration rate (GFR) measurement using Tc-99m-DTPA in correlation with GFR by I-125-iothalamate method. MATERIAL AND METHODS: The study populations were 63 adults with 39 men and 24 women aged from 20 to 59 yrs (mean = 37.9 yrs). The following five background regions of interest were used in measurement of GFR using Gates' method: 1) lower side of each kidney (subrenal), 2) around each kidney (circumferential), 3) upper side of each kidney (suprarenal), 4) lateral side of each kidney (lateral), 5) between the two kidneys (inter-renal). We also measured GFR using I-125-iothalamate in each subject. The two studies were separated by 1 to 3 weeks. The subjects were divided into two groups by renal depth. Group 1 with renal depth> or=7cm and group 2 with renal depth or=7cm. CONCLUSION: GFRs measured with Gates' method showed higher correlation with the GFR measured by I-125-iothalamate when the regions of interest were placed over the suprarenal and inter-renal backgrounds. And GFRs measured with Gates method showed statistically significant correlation with the GFR measured by I-125-iothalamate in the group with renal depth < 7cm.

Preoperative Cisternoscintigraphy As a Guide to Therapeutic Decision Making for Cystic Subdural Hygroma / 대한핵의학회잡지

We report a case of a patient with cystic subdural hygroma who underwent pre-operative Tc-99m DTPA cistrenoscintigraphy to determine the course of operation. A 68-year-old female was admitted to the department of neurosurgery because of acute subarachnoid hemorrhage. After emergency ventricular drainage, the hydrocephalus and cystic subdural hygroma in the right fronto-temporal area developed. She underwent Tc-99m DTPA cisternoscintigraphy to evaluate the type of hydrocephalus, which revealed obstructive communicating hydrocephalus and the communication between the subdural hygroma and the subarachnoid space. As a result of these findings, she underwent the ventriculo-peritoneal shunt operation without removal of the subdural hygroma. Post-operative brain CT showed nearly normalized shape and size of the right ventricle and disappearance of subdural hygroma. We recommend the pre-operative cisternoscintigraphy in patients with complex hygroma to evaluate the communication between subdural hygroma and the subarachnoid space.

Development of Formulas for the Estimation of Renal Depth and Application in the Measurement of Glomerular Filtration Rate in Koreans / 대한핵의학회잡지

PURPOSE: There is no established formula for estimating renal depths in Korean. As a result, we undertook this study to develop a new formula, and to apply this formula in the calculation of glomerular filtration rate (GFR). MATERIALS AND METHODS: We measured the renal depth (RD) on the abdominal CT obtained in 300 adults (M:F=167:133, mean age 50.9 years) without known renal diseases. The RDs measured by CT were compared with the estimated RDs based on the Tonnesen and Taylor equations. New formulas were derived from the measured RDs in 200 out of 300 patients based on several variables such as sex, age, weight, and height by multiple regression analysis. The RDs estimated from the new formulas were compared with the measured RDs in the remaining 100 patients as a control. In 48 patients who underwent Tc-99m DTPA renal scintigraphy, GFR was measured with three equations (new formula, Tonnesen and Taylor equations), respectively, and compared with each other. RESULTS: The mean values of the RDs measured from CT were 6.9 cm for right kidney of the men (MRK), 6.7 cm for left kidney of the men (MLK), 6.7 cm for right kidney of the women (WRK), and 6.6 cm for left kidney of the women (WLK). The RDs estimated from Tonnesen equation were shorter than the ones measured from CT significantly. The newly derived formulas were 12.813 (weight/height)+0.002 (age)+ 2.264 for MRK, 15.344 (weight/height)+0.011 (age)+0.557 for MLK, 12.936 (weight/height)+ 0.014 (age)+1.462 for WRK and 13.488 (weight/height)+0.019 (age)+0.762 for WLK. The correlation coefficients of the RD measured from CT and estimated from the new formula were 0.529 in MRK, 0.729 in MLK, 0.601 in WRK, and 0.724 in WLK, respectively. The GFRs from the new formula were significantly higher than those from the Tonnesen equation significantly, which was the most similar to normal GFR values. CONCLUSION: We generated new formulas for estimating RD in Korean from the data by CT. By adopting these formulas, we expect that GFR can be measured by the Gates method accurately in Korean.

Evaluation of Spontaneous Intracranial Hypotension Using Radionuclide Cisternography / 대한핵의학회잡지

We report four cases of spontaneous intracranial hypotension that were investigated by radionuclide cisternography Tc-99m-diethylenetriamine pentaacetic acid radionuclide cisternography of all our patients showed direct sign of cerebrospinal fluid leakage as well as indirect signs of less activity than expected over the cerebral convexities and rapid appearance of bladder activity. The headache of all patients was eventually controlled with bed rest and hydration.

A Case of Spontaneous Intracranial Hypotension: Detection of Cerebrospinal Fluid Leakage by Early Dynamic Radionuclide Cisternography / 대한핵의학회잡지

Although cerebrospinal fluid leakage is suggested as one of the causes of spontaneous intracranial hypotension, on]y a few cases with direct evidence of cerebrospinal fluid leakage on radionuclide cisternography have been reported in the literature Indirect evidences of cerebrospinal fluid leakage such as early visualization of the soft tissue and bladder or delayed migration of radiotracer have been observed in most patients with spontaneous intracranial hypotension. We report a case of spontaneous intracranial hypotension in which cerebrospinal fluid leakage was directly demonstrated by early dynamic imaging of spine on radionuclide cisternography. We suggest that early dynamic imaging of spine is an important adjunctive procedure in detecting cerebrospinal fluid leakage in patients with spontaneous intracranial hypotension.

Clinical Usefulness of GFR Measurement Using Tc-99m DTPA Renal Scan in Kidney Transplantation Patients / 대한신장학회잡지

In clinical practice, Tc-99m DTPA renal scan has been using for screening for the presence of renal dysfunction to determine the need for early treatment in kidney transplantation patients. We measured glomerular filtration rate(GFR) using Gates method during the routine Tc-99m DTPA renal scan, predicted creatinine clearance estimated by Cockcroft and Gault formula and 24-hour creatinine clearance and compared each other in 88 kidney transplantation patients simultaneously. The range of renal uptake(%) of Tc-99m DTPA was from 1.8% to 10.4% and the correlation between 24-hour creatinine clearance and renal uptake showed Y=7.176X8.975Y=creatinine clearance(ml/min), X=renal uptake(%) and the correlation coefficient was 0.771. The correlation coefficient between GFR (ml/min) using Tc-99m DTPA renal scan and predicted creatinine clearance was 0.765. The correlation coefficient between predicted creatinine clearance and 24-hour creatinine clearance was 0.850. We concluded that the measurement of GFR using Tc-99m DTPA renal scan was clinically useful in kidney transplantation patients with the advantage of simplicity, low expense, opportunity for renal imaging.

Radionuclide Cisternographic Findings in Patients with Spontaneous Intracranial Hypotension / 대한핵의학회잡지

PURPOSE: Radionuclide cisternography may be helpful in understanding pathophysiology of postural headache and low CSF pressure in patients with spontaneous intracranial hypotension. The purpose of this study was to characterize radionuclide cisternographic findings of spontaneous intracranial hypotension. MATERIALS AND METHODS: The study population consists of 15 patients with spontaneous intracranial hypotension. Diagnosis was based on their clinical symptoms and results of lumbar puncture. All patients underwent radionuclide cisternography following injection of 111 to 222 MBq of Tc-99m DTPA into the lumbar subarachnoid space. Sequential images were obtained between 1/2 hour and 24 hour after the injection of Tc-99m DTPA. Radioactivity of the bladder, soft tissue uptake, migration of radionuclide in the subarachnoid space, and extradural leakage of radionuclide were evaluated according to the scan time. RESULTS: Radionuclide cisternogram showed delayed migration of radionuclide into the cerebral convexity (14/15), increased soft tissue uptake (11/15), and early visualization of bladder activity at 30 min (6/10) and 2 hr (13/13). Cisternography also demonstrated leakage site of CSF in 4 cases and 2 of these were depicted at 30 min. Epidural blood patch was done in 11 patients and headache was improved in all cases. CONCLUSION: The characterstic findings of spontaneous intracranial hypotension were delayed migration of radionuclide and early visualization of the soft tissue and bladder activity. These scintigraphic findings suggest that CSF leakage rather than increased CSF absorption or decreased production may be the main pathophysiology of spontaneous intracranial hypotension. Early and multiple imaging including the bladder and soft tissue is required to observe the entire dynamics of radionuclide migration.