Parenchymal mean transit time analysis of 99mTc-DTPA captopril renography.

Proposed renal hemodynamic mechanisms of captopril suggest that quantitation of renographic retention parameters should help identify patients suspected of having renovascular disease. The parenchymal mean transit time (MTT) is theoretically superior to other measures of retention, but data supporting its superiority are few. METHODS: Two groups of subjects were studied with diethylenetriamine pentaacetic acid (DTPA) baseline and captopril renography, one (n = 43) with demographically defined essential hypertension (group I) and the other (n = 60) with a high prevalence of renovascular disease (group II). Abnormal parenchymal MTT values were derived from the statistical confidence limits of group I data and then applied to group II subjects for comparison with angiographic results. RESULTS: Depending on the sensitivity of the threshold chosen, specificity varied, but the overall accuracy of baseline parenchymal MTT for renovascular hypertension detection ranged from 54% to 58%. Change in parenchymal MTT (post-captopril - pre-captopril) accuracy was 55%-61% and was not significantly different. Neither method improved on previously reported quantitative or qualitative criteria. Group II subjects had significantly worse renal function than did group I subjects, and 23% had nondiagnostic renograms. CONCLUSION: Parenchymal MTT analysis of DTPA captopril renography is not more accurate and offers no advantages compared with qualitative renography or with more commonly used renographic measures in our subjects. This may relate to the high prevalence of renal dysfunction in our population. In subjects with renal dysfunction, the low sensitivity and the trend toward low specificity of parenchymal MTT do not support its routine use for the evaluation of renovascular disease among patients suspected of having renovascular hypertension.     

A multiple regression analysis for accurate background subtraction in 99Tcm-DTPA renography

A technique for accurate background subtraction in 99Tcm-DTPA renography is described. The technique is based on a multiple regression analysis of the renal curves and separate heart and soft tissue curves which together represent background activity. It is compared, in over 100 renograms, with a previously described linear regression technique. Results show that the method provides accurate background subtraction, even in very poorly functioning kidneys, thus enabling relative renal filtration and excretion to be accurately estimated.     

A comparison of deconvolution and the Patlak-Rutland plot in renography analysis.

Deconvolution and the Patlak-Rutland plot are two of the most commonly used methods for analyzing dynamic radionuclide renography. Both methods allow estimation of absolute and relative renal uptake of radiopharmaceutical and of its rate of transit through the kidney. METHODS: A theoretical comparison of uptake assessment by both techniques is made and a mathematical derivation of the relationship between mean transit time (MTT) and renal outflow efficiency (ROE) is presented. The validity of these theoretical findings was tested in a series of 120 renograms obtained using 99mTc-mercaptoacetyltriglycine (MAG3). RESULTS: The estimates of renal uptake obtained are theoretically equivalent. The renogram measurements confirmed this, because there was no significant systematic difference in relative counts obtained by the two methods. Absolute counts were significantly higher for the deconvolution measurements, but only by 2.0%. The SDs of the differences between the two techniques, expressed as a percentage of the mean, were 1.7% and 5.4% for relative and absolute counts, respectively. There was an inverse monotonic relationship between MTT and ROE. ROE evaluated at a particular time was shown to depend on absolute renal function. Measured values of MTT and ROE were consistent with the theoretical prediction. CONCLUSION: The two approaches to renogram analysis provide consistent parameters for both uptake and transit evaluation.     

Comparison of left anterior oblique and geometric mean gastric emptying

A left anterior oblique image (LAO) and the geometric mean of anterior and posterior counts have both been proposed as methods for acquiring gastric emptying data. Both approaches are used to correct for the changes in attenuation that occur as the depth of radiolabeled solids changes during gastric emptying. These two methods were compared by using a power exponential curve fit to calculate a lag phase, an equilibrium emptying rate, and a half-time for gastric emptying in 20 patients. There were no significant differences (mean +/- 1 s.e.m.) in the measured half-emptying time (115 +/- 10 versus 104 +/- 7 min) (p = 0.08) or rate of gastric emptying (0.015 +/- 0.002 versus 0.015 +/- 0.002 min-1) (p = 0.56) for LAO imaging versus the geometric mean. However, the LAO measurements of the lag phase were significantly higher (69 +/- 7 min) than the geometric mean (53 +/- 6 min) measurements (p = 0.004). This resulted in 4/20 (20%) of patients with normal geometric mean lag phase measurements who would have been reclassified as abnormal using the LAO method.     

应用图像后处理技术测量和分析人体颈动脉分叉血管几何学指标

目的 初步应用MR血管影像结合计算机三维图像后处理技术测量和分析在体颈动脉分叉的几何学属性指标,探讨不同年龄组该段血管形态的差异.方法 搜集2005年至2007年经超声检查或DSA检查证实为颈动脉分叉正常或狭窄率小于30%的受检者57例,分为≤40岁组27例和>40岁组30例,行颈动脉1VIR增强血管成像(CEMRA)检查,扫描所得减影图像经计算机图像后处理重建三维血管图像并测量颈动脉分叉的各项几何学指标.采用嵌套设计方差分析方法分析两组的各项测量指标的差异是否有统计学意义.结果 >40岁组和≤40岁组的颈动脉分叉几何学指标分别为:分叉角:70.268°±16.050°和58.857°±13.294°,颈内动脉(ICA)角:36.893°±11.837°和30.275°±9.533°,ICA非平面角:6.453°±5.009°和6.263°±4.250°,颈总动脉(CCA)曲率:0.023±0.011和0.014±0.005,ICA曲率:0.070±0.042和0.046±0.022,ICA/CCA直径比:0.693±0.132和0.728±0.106,颈外动脉(ECA)/CCA直径比:0.750±0.123和0.809±0.122,ECA/ICA直径比:1.103±0.201和1.127±0.195;分叉面积比:1.057±0.281和1.291±0.252.>40岁组和≤40岁组的分叉角、ICA角、CCA曲率、ICA曲率、ECA/CCA直径比和分叉面积比的差异有统计学意义(F值分别为17.16、11.74、23.02、13.38、6.54、22.80,P值均<0.05).结论 应用MR血管成像结合图像后处理方法实现了在体颈动脉分叉的三维立体重组和其各项几何学指标的测量,为进一步分析血管几何形态与血流动力学状态的关系以及其与动脉粥样硬化病变的发生与发展提供了一种崭新而简便易行的技术.     

Radionuclide renography: A personal approach

Recent advances have increased the value of radionuclide renography in evaluating the patient with suspected disease of the genitourinary tract. The use of the consensus process to help standardize procedures and recommend interpretative criteria provides guidance for the nuclear medicine practitioner, serves as a basis to improve the standard of practice, and facilitates pooling of data from different centers. This review draws on the consensus criteria to present a personal approach to radionuclide renography with a particular emphasis on diuresis renography and the detection of renovascular hypertension. Patients are encouraged to come well hydrated and void immediately prior to the study. Our standard radiopharmaceutical is 99mTc mercaptoacetyltriglycine (MAG3). Routine quantitative indices include a MAG3 clearance, whole kidney and cortical (parenchymal) regions of interest, measurements of relative uptake, time to peak height (Tmax), 20 min/max count ratio, residual urine volume and a T(1/2) in patients undergoing diuresis renography. A 1-minute image of the injection site is obtained at the conclusion of the study to check for infiltration because infiltration can invalidate a plasma sample clearance and alter the renogram curve. A postvoid image of the kidneys and bladder is obtained to calculate residual urine volume and to better evaluate drainage from the collecting system. In patients undergoing diuresis renography, the T(1/2) is calculated using a region of interest around the activity in the dilated collecting system. A prolonged T(1/2), however, should never be the sole criterion for diagnosing the presence of obstruction; the T(1/2) must be interpreted in the context of the sequential images, total and individual kidney function, other quantitative indices and available diagnostic studies. The goal of ACE inhibitor renography is to detect renovascular hypertension, not renal artery stenosis. Patients with a positive study have a high probability of cure or amelioration of the hypertension following revascularization. In patients with azotemia or in patients with a small, poorly functioning kidney, the test result is often indeterminate (intermediate probability) with an abnormal baseline study that does not change following ACE inhibition. In patients with normal renal function, the test is highly accurate. To avoid unrealistic expectations on the part of the referring physician, it is often helpful to explain the likely differences in test results in these two-patient populations prior to the study.     

An analysis of the diagnostic contribution of double-radiocompound renography

The diagnostic contribution of double-radiocompound renography was tested by applying discriminant analysis to the data obtained in one group of normal subjects and in some groups of selected pathological cases which included glomerulonephritis, pyelonephritis, and hypertension. The results obtained confirm the reliability of the test and give evidence of its usefulness in diagnostic clinical work.Report presented at the First E.N.M.S. Congress, Lausanne, May 1976     

Comparison of gastric emptying scintigraphy based on the geometric mean of the gastric proportion of the abdominal radioactivity or on the geometric mean of the intragastric radioactivity

PURPOSE: Using gastric emptying scintigraphy the gastric retention rate is commonly calculated within a gastric region of interest (intragastric method). This technique may have significant limitations when left oblique anterior views are acquired, due in part to attenuation resulting from intragastric redistribution. To minimize these drawbacks, it was proposed to express the intragastric content as a percentage of the abdominal radioactivity (abdominal method). Our goal was to compare these two methods when anterior-posterior scanning is used. METHODS: Antero-posterior scintigraphic data of 272 consecutive patients were analysed by both methods. Retention rates were obtained by both observation and calculation by power exponential fit. Gastric emptying parameters (half-emptying time of solids (T(50,S)) and liquids (T(50,L)), lag phase (T(lag)) time and real emptying time (T(RE))), and quality of fit were also computed and compared. RESULTS: For solids, the intragastric method resulted in weakly higher experimental retention rates, whereas retention rates were quite similar for liquids. Differences between experimental and calculated retention rates were smaller for abdominal method, for both liquids and solids. As a result, values for the quality of fit were higher for the abdominal method. Significant differences were observed only for calculated T(50,S) (122+/-46 min vs. 124+/-48 min, mean difference 2+/-2 min, P<0.00001) and T(RE) (163+/-64 min vs. 168+/-68 min, mean difference 4.5+/-3.8 min, P<0.05), respectively, for the abdominal and the intragastric methods. However, the Bland-Altman statistical method revealed good agreements (<5% outliers). CONCLUSION: Intragastric and abdominal methods can be used indifferently to treat antero-posterior data of gastric scintigraphy.     

Quantitative renography with the organ volume method and interporative background subtraction technique

When quantification of renal activity is performed by planar imaging, many correction factors must be considered. To obtain quantitative renal images and renogram, we have examined our proposed method by using the organ volume for scatter, attenuation, and background activity, and the interporative background subtraction (IBS) technique in phantom and clinical studies. A renal phantom study was performed by varying the renal depth from 3 to 11 cm and the kidney-to-background activity concentration ratio from 5 to 80. Planar images were properly corrected for scatter, attenuation and background activity by our method and the corrected images were compared with the images obtained by the conventional method for the estimation of true renal activity. Clinical Tc-99m DTPA dynamic data for both a good and a poor renal function were also corrected by our method and volume-corrected renograms were obtained. For the phantom study, depth-independent images were obtained and these images gave a good estimation of the true count rate. In the clinical study, the conventional renogram was especially modified to allow for oversubtraction of background counts in the early phase (0–4 min). In conclusion, our proposed correction method can assess renal function qualitatively and quantitatively in both static and dynamic planar renal imaging.     

Dynamic geometric mean studies using a single headed rotating gamma camera

A technique for acquiring dynamic geometric mean studies utilizing a single-headed rotating gamma camera has been developed. The camera head is repeatedly rotated between opposed views under computer control. A single data set results, from which a dynamic sequence of geometric mean images can be produced. Software has been developed to accomplish data acquisition and the reformatting required. The accuracy of the geometric mean data formed using this technique has been studied experimentally, and compared with results obtained from anterior and posterior sequences. In a simple clearance experiment of a 1-I volume with a known clearance of 20 ml.min-1, the geometric mean data resulted in estimates of volume remaining in the container with a mean error or +2.0 ml (s.d. = 5.7 ml, range -4.5 +/- 15.3 ml), while the anterior and posterior images yielded volume estimates with mean errors of -10.1 ml (s.d. = 16.6 ml, range -47.4 +/- 10.5 ml) and +35.5 ml (s.d. = 22.6 ml, range -3.2 +/- 51.6, ml), respectively. The technique is easy to implement and does not require modification of existing hardware. An application of the technique to a clinical study of gastric emptying is also included.     

Quantitative analysis of infantile ureteropelvic junction obstruction by diuretic renography

Infantile hydronephrosis detected by ultrasonography poses a clinical dilemma on how to treat the condition. This article reports a retrospective study to evaluate infantile hydronephrosis due to suspected ureteropelvic junction (UPJ) obstruction by means of standardized diuretic renography and to speculate its usefulness for quantitative assessment and management of this condition. Between November 1992 and July 1999, 43 patients who had the disease detected in their fetal or infantile period were submitted to this study. Standardized diuretic renograms were obtained with 99mTc-labeled diethylene-triaminepenta-acetate (Tc-99m-DTPA) or 99mTc-labeled mercaptoacetyl triglycine (Tc-99m-MAG3) as radiopharmaceuticals. Drainage half-time clearance (T 1/2) of the activity at each region of interest set to encompass the entire kidney and the dilated pelvis was used as an index of quantitative analysis of UPJ obstruction. Initial T 1/2s of 32 kidneys with suspected UPJ obstruction were significantly longer than those of 37 without obstruction. T 1/2s of kidneys which had undergone pyeloplasty decreased promptly after surgery whereas those of units followed up without surgery decreased more sluggishly. These findings demonstrate that a standardized diuretic renographic analysis with T 1/2 can reliably assess infantile hydronephrosis with UPJ obstruction and be helpful in making a decision on surgical intervention.     

Validity of the geometric mean correction in the quantification of whole bowel transit

The accurate interpretation of gastrointestinal transit studies often requires quantification of the data. Particles radiolabelled with indium-111 have been monitored using a gamma camera, during transit through the stomach and the small and large intestines of normal subjects. The count rates measured from either anterior or posterior images alone showed considerable variations, and depended on the site of the tracer within the gut. The geometric mean values of corresponding anterior and posterior count rates remained almost constant throughout each study.     

A computer-video aided time motion analysis technique for match analysis.

The purpose of this study was to find out suitable methods for obtaining objective data on the time spent by players of different positions during walking, jogging, cruising, sprinting and standing still during match play activities. Computer programs and filming analyses with a simple notation system based upon symbolic representations of movements have been devised for analysis of individual players' behaviour. A technique was devised and employed with a small group of university players, aged 19-21 years of age. The subjects were filmed in several matches, and the video recordings were analysed using a microcomputer. The ratio of the time spent for the players were 56% walking, 30% jogging, 4% cruising, 3% sprinting and 7% standing still. ANOVA revealed that there are significant differences among the players for different positions on the field, for example the time spent on walking, jogging and standing still differed (P less than 0.05) among attackers, defenders and midfielders. A new method has been developed to obtain reliable information about the players' movement and performance in the game. The Authors believe that there should be further studies carried out involving more teams at different levels of performance to substantiate these preliminary findings.     

Area normalization of the renal region of interest in radionuclide renography data analysis: A misconception

Relative renal function is estimated by comparing the area under the second segment of the curve from the renal region of interest in a renographic study. We have examined the problems arising out of area normalization of the renal region of interest in the data analysis for relative renal function evaluation. Error analysis by computer simulation proves that this method of data analysis is highly misleading and erroneous.     

Comparison of left anterior oblique, anterior and geometric mean methods for determining gastric emptying times.

The accurate determination of gastric emptying time requires correction or compensation for tissue attenuation. The gold standard for tissue attenuation correction for gastric emptying is the geometric mean of the gastric counts from the anterior and posterior views. For reasons of efficiency, many community hospitals acquire only the anterior projection. This study addressed the hypothesis that, using the left anterior oblique view alone, one can minimize the effect of variation in attenuation as the meal moves from the fundus to the stomach to the more anterior antrum to a degree equal to that of the geometric mean technique. We studied 42 consecutive patients using a standardized 300-g meal labeled with 650 muCi of 99mTc-sulfur colloid. The patients were imaged in the anterior (ANT), posterior (POST) and left anterior oblique (LAO) views every 15 min for 90 min. Linear regressions were obtained using the ANT, LAO and GM data. Cross-correlation of the T1/2 for 35 cases showed an R value for the GM versus LAO of 0.95 and GM versus ANT of 0.84. The p value greater than 0.49, for the paired two-tailed t-test of the LAO and GM methods. The p value for the ANT and GM methods is 0.0058 indicating a significant difference between these methods. The cross-correlation, F-test p and t-test p values support the hypothesis that there is no significant difference between the geometric mean and left anterior oblique gastric emptying times. It is therefore reasonable to substitute the left anterior oblique for routine GET when using a solid meal in patients with normal gastric anatomy, albeit altered physiology.     

New automated physical phantom for renography.

Physical phantoms have been used to test the diagnostic proficiency of nuclear medicine professionals and the accuracy of their equipment in external quality assurance surveys. No dynamic renal phantoms are commercially available. A new renal phantom, presented in this paper, was constructed and patented in the United States. METHODS: The organs to be simulated by the phantom were in the form of containers filled with radioactive solution, and the device further comprised movable steel and lead plates between the containers and the gamma-camera. The detectable radiation was regulated in accordance with automated computer-controlled step motors to move the attenuators to simulate a given patient situation. The reproducibility of the phantom measurements was defined as a coefficient of variation. Four different kidney-function simulations were repeated 3 times, and 6 parameters were compared. RESULTS: The average root mean square deviation of the coefficient of variation was 6.7% for the perfusion integral, 1.3% for time to reach the maximum activity, 19.7% for mean transit time, 3.3% for function (Patlak [%]), 1.0% for outflow index (%), and 6.5% for time to reach the half-activity from maximum. CONCLUSION: With this phantom, the true values of most parameters measured are well known; it closely approaches true extraction, washout, and attenuation properties and curves, and the images produced are similar to those of patient studies. Compared with the first manual version, this new automated phantom is easy to use. Any desired clinical situation can be programmed. It is a promising tool for quality assurance and calibration of renography.     

Appropriate selection of background for 99Tcm-DTPA renography

Since 99Tcm-DTPA is diffusible and not significantly protein bound in plasma, it rapidly enters the extravascular space following injection. Therefore, during the first few minutes of the DTPA renogram, the period on which the measurements of individual kidney glomerular filtration rate and differential function are based, background activity comprises a rising extravascular signal and a falling intravascular signal. The aim of this study was to measure the ratio of these two signals in background present within the renal region of interest (ROI) and compare it with the ratio in a background ROI. An appropriate background ROI is one in which the ratio is equal to that in background in the renal ROI. To pursue this aim, we quantified the rates of change of the intravascular and extravascular activities in background and, by comparing them with the rate of increase of filtered activity, expressed them as GFR equivalents (the intravascular being negative). It is impossible, from a single renogram, to separate the rising extravascular signal from the signal due to filtered activity, and therefore impossible to quantify the extravascular GFR equivalent present in background within the renal ROI. We therefore studied six patients undergoing bone marrow transplantation before and after cyclosporin treatment. By comparing the dynamic renographic data between the two sequential studies, the substantial fall in GFR (from 107 +/- 12 S.D. to 49 +/- 7 ml min-1) permitted separate quantification of the extravascular GFR equivalent in the renal ROI in both studies. Three of the patients were studied on a third occasion after cyclosporin. In two, GFR remained low and these studies were paired with corresponding baseline studies, while in the other it increased and this was compared with the nephrotoxic study, giving a total of nine paired studies between which GFR changed. The ratio of intravascular to extravascular GFR equivalents in a background ROI placed above the kidney was considerably greater, and in a background ROI below the kidney considerably less, than that in the renal ROI. A background ROI which was the difference between the renal ROI and a perirenal ROI, 2 pixels outside the renal ROI along the horizontal and 1 pixel outside along the vertical, gave a ratio almost identical to that of the background within the renal ROI (renal ROI ratio:background ROI ratio = 1.09 +/- 0.17 S.D., n = 18).(ABSTRACT TRUNCATED AT 400 WORDS)     

Guidance document for structured reporting of diuresis renography

This Guidance Document for structured reporting of diuresis renography in adults was developed by the International Scientific Committee of Radionuclides in Nephro-urology (ISCORN; http://www.iscorn.org). ISCORN chose diuresis renography for its first structured report Guidance Document because suspected obstruction is the most common reason for referral, most radionuclide renal studies are conducted at institutions that perform fewer than 3 studies per week, and a large percentage of studies are interpreted by physicians with limited training in nuclear medicine. Ten panelists were asked to categorize specific reporting elements as essential, recommended, optional (without sufficient data to support a higher ranking), and unnecessary (does not contribute to scan interpretation or quality assurance). The final document was developed through an iterative series of comments and questionnaires with a majority vote required to place an element in a specific category. The Guidance Document recommends a reporting structure organized into indications, clinical history, study procedure, findings and impression and specifies the elements considered essential or recommended in each category. The Guidance Document is not intended to be restrictive but, rather, to provide a basic structure and rationale so that the diuresis renography report will: (1) communicate the results to the referring physician in a clear and concise manner designed to optimize patient care; (2) contain the essential elements required to evaluate and interpret the study; (3) clearly document the technical components of the study necessary for accountability, quality assurance and reimbursement; and (4) encourage clinical research by facilitating better comparison and extrapolation of results between institutions.