Subject(s)
Bipolar Disorder/diagnosis , Graves Disease/psychology , Psychotic Disorders/etiology , Thyroid Gland/pathology , Adolescent , Affective Disorders, Psychotic/diagnosis , Antipsychotic Agents/therapeutic use , Antithyroid Agents/therapeutic use , Benzodiazepines/therapeutic use , Bipolar Disorder/drug therapy , Bipolar Disorder/etiology , Delirium/diagnosis , Diagnosis, Differential , Female , Graves Disease/drug therapy , Graves Disease/surgery , Humans , Methimazole/therapeutic use , Olanzapine , Radionuclide Imaging , Thyroid Gland/diagnostic imaging , ThyroidectomyABSTRACT
OBJECTIVE: To validate a method to assess glomerular filtration rate (GFR) in conscious monkeys via transcutaneous radiation detection after IV injection of technetium Tc 99m pentatate (99mTc-DTPA). ANIMALS: 4 healthy rhesus monkeys. PROCEDURES: On day 1, each monkey was anesthetized, lothalamate sodium I 125 (125l-iothalamate) was administered via continuous rate infusion (0.0037 MBq/min); blood and urine samples were obtained for determination of 125l-iothalamate plasma clearance variables and estimation of GFR. One dose of 99mTc-DTPA (74 MBq/kg, IV) was also administered during the 125l-iothalamate plasma clearance test, and transcutaneous measurements of technetium 99m-emitted radiation were obtained by use of an ambulatory renal monitor (ARM) applied to a brachium of each monkey. Determination of GFR by use of the ARM was repeated on days 8 and 45 in the same monkeys without anesthesia. RESULTS: Sensitivity, accuracy, and precision of the 2 methods were similar. By use of the ARM, GFR determined by use of the renal rate constant (κGFR) was calculated; the value obtained on day 1 under anesthesia was similar to values determined via 125l-iothalamate plasma clearance testing on the same day, but was 16% to 23% less than that measured on days 8 and 45 in conscious monkeys. CONCLUSIONS AND CLINICAL RELEVANCE: The ARM method for assessment of GFR was less invasive, faster, and more convenient than the standard clearance method, but yielded comparable results. The need to train animals and size restrictions of the device may limit the use of this technique in other nonhuman animals.
Subject(s)
Anesthesia/veterinary , Consciousness/physiology , Glomerular Filtration Rate/physiology , Macaca mulatta/physiology , Animals , Arm/physiology , Body Weight , Female , Iodine Radioisotopes/pharmacokinetics , Iothalamic Acid/pharmacokinetics , Kidney/physiology , Male , Monitoring, Ambulatory/methods , Monitoring, Ambulatory/veterinary , Technetium Tc 99m Pentetate/pharmacokineticsABSTRACT
An easy and accurate assessment of the renal function is a critical requirement for detecting the initial functional decline of the kidney induced by acute or chronic renal disease. A method for measuring the glomerular filtration rate is developed with the accuracy of clearance techniques and the convenience of plasma creatinine. The renal function is measured in rats as the rate of clearance determined from time-resolved transcutaneous fluorescence measurements of a new fluorescent glomerular filtration agent. The agent has a large dose-safety coefficient and the same space distribution and clearance characteristics as iothalamate. This new approach is a convenient and accurate way to perform real-time measurements of the glomerular filtration rate to detect early kidney disease before the renal function becomes severely and irreversibly compromised.
Subject(s)
Fiber Optic Technology/instrumentation , Glomerular Filtration Rate/physiology , Image Interpretation, Computer-Assisted/methods , Microscopy, Fluorescence/instrumentation , Spectrometry, Fluorescence/instrumentation , Animals , Computer Systems , Equipment Design , Equipment Failure Analysis , Microscopy, Fluorescence/methods , Rats , Spectrometry, Fluorescence/methodsABSTRACT
UNLABELLED: We developed a noninvasive method for the mapping of regional renal blood flow in humans using PET and H(2)(15)O. METHODS: Fifteen subjects participated in the study, 5 with normal renal function and 10 with renal disease. The protocol used a whole-body PET scanner, intravenous bolus injection of 1,110-1,850 MBq H(2)(15)O and sequential imaging at 3 s per frame. (131)I-Iodohippuran was used to independently assess effective renal plasma flow in each subject. Hippuran clearance and renal blood flow (RBF) were measured twice, before and after treatment with probenecid, to verify that RBF is not affected. Flow analysis was based on the Kety model, according to the operational equation: C(t) = F integral C(a)(u)du - k integral C(u)du, where F is the RBF, k is the tissue-to-blood clearance rate, C is the PET concentration, and C(a) is the tracer concentration in the abdominal aorta. F and k were estimated by linear least squares on a pixel-by-pixel basis to produce quantitative maps (parametric images) of RBF. The flow maps were analyzed by regions of interest (largely excluding the medulla and collecting system) for each kidney on each slice and pooled to yield mean RBF. RESULTS: In the 5 healthy subjects, mean RBF was 3.4 +/- 0.4 mL/min/g. There was no difference in flow between kidneys (t = -0.59; n = 11; P > 0.95). Before treatment with probenecid, RBF was linearly related to hippuran clearance (r(2) = 0.92). Probenecid treatment significantly reduced hippuran clearance (P < 0.003), but RBF was unchanged (P > 0.17). Compared with healthy control subjects, RBF was significantly decreased in patients with renal disease (P < 0.002). Flow maps were of good quality in all subjects, exhibiting characteristic patterns, with higher values in regions composed largely of renal cortex. CONCLUSION: Parametric mapping of RBF with PET and H(2)(15)O provides a straightforward, noninvasive method for quantitative mapping of RBF, which may prove useful in research applications and in the management of patients whose therapy alters renal tubular transport.
