Biomedical subjects
G T Krishnamurthy
Publications and source records attributed to G T Krishnamurthy.
Gallbladder dynamics induced by a fatty meal in normal subjects and patients with gallstones: concise communication.
A study was undertaken to establish the pattern of gallbladder emptying in normal subjects and in patients with gallstones, using a fatty meal as stimulus to release endogenous cholecystokinin. The time from meal ingestion to beginning of gallbladder emptying (latent period), the total duration of emptying (ejection period), degree of emptying (ejection fraction), and the rate of emptying (ejection fraction/ejection period) were measured noninvasively by a nongeometric scintigraphic technique. The mean latent period and ejection rate were similar in normal subjects and patients with gallstones, but the mean ejection period and ejection fraction were significantly reduced in the patients. This study suggests that for an identical stimulus, the gallbladder in cholelithiasis begins to empty at the normal time but empties for a shorter duration; the result is a reduction of ejection fraction but not of ejection rate.
The gallbladder emptying response to sequential exogenous and endogenous cholecystokinin.
The gallbladder emptying response to sequential exogenous and endogenous cholecystokinin was measured by a noninvasive, nongeometric scintigraphic technique using a single dose of technetium 99m-labelled hepatobiliary agent. The mean latent period, ejection period, ejection fraction and ejection rate following 3 min infusion of 40 ng kg-1 of octapeptide of cholecystokinin were 2.8 +/- 0.7 min, 9.8 +/- 1.3 min, 34.0 +/- 9.9% and 3.5 +/- 2.0% per minute respectively. The corresponding values following 8 oz/70 kg of oral fatty meal were 15 +/- 6 min, 24.0 +/- 5 min (P less than 0.05), 55 +/- 9.1% and 2.8 +/- 0.6% per minute respectively. The total emptying for the combined stimuli was 71.4 +/- 14.0%. The wider range in latent and ejection period following fatty meal probably reflected the variations in time of the release into circulation and the duration of bioavailability of endogenous cholecystokinin. The lower rate of ejection was over compensated by longer duration of ejection resulting in higher degree of emptying following fatty meal. It is concluded that the gallbladder emptying pattern to exogenous and endogenous cholecystokinin can be studied sequentially using a single dose of technetium 99m-labelled hepatobiliary agent.
Scintigraphic variations of normal biliary physiology.
We studied 115 healthy adult volunteers, fasting overnight, to establish the normal scintigraphic variability. Five Tc-99m IDA agents with liver excretion half-times ranging from 18 to 108 min were used. The time of appearance of the common bile duct correlated directly with the liver's excretion half-time. The appearance of the gallbladder and the small intestine were independent of the excretion half-time and showed a reciprocal relationship suggesting a major role for the sphincter of Oddi. In 22% of the subjects, the sphincter tonus was tight enough to divert all of the hepatic bile into the gallbladder, allowing none into the intestine. All of such subjects showed normal dynamic response to intravenous cholecystokinin. The pattern of the bile drainage from the two lobes differed, resulting in asymmetry of the right and left hepatic ducts. It is concluded that the selection of a Tc-99m IDA agent should be based on the clinical problem at hand and that a clinician's understanding of the scintigraphic variability in normal subjects is critical before attempting diagnosis.
Comparison of biokinetics and biliary imaging parameters of four Tc-99m iminodiacetic acid derivatives in normal subjects.
The biokinetics (blood clearance, urinary excretion, hepatic peak time, uptake, and excretion t-1/2) and the imaging parameters (the time of appearance of the common bile duct, gallbladder, and duodenum) were determined in 34 normal subjects using Tc-99m diethyl (EIDA), Tc-99m dimethyl (HIDA), Tc-99m paraisopropyl (PIPIDA), and Tc-99m parabutyl (PBIDA) iminodiacetic acid derivatives. The blood and hepatic clearance of the four agents were significantly different (P less than 0.05) from each other. The 24-hour urinary excretion of PBIDA was significantly lower (P less than 0.05) than the urinary excretion of the other three agents. There was no difference among the four agents in the time of appearance of the gallbladder and duodenum. The time of appearance of the common bile duct was significantly delayed with PBIDA. The maximum intensity of the common bile duct usually occurred between 20 to 40 minutes with all four agents. However, gallbladder intensity continued to increase up to 3 hours. It is concluded that in the presence of normal liver function, all four Tc-99m IDA agents show definite differences in biokinetics but these differences do not have a major effect on biliary imaging parameters. If imaging alone is the primary goal, the selection of any one of the four agents will meet the clinican's need satisfactorily.
Changing publication trends in nuclear medicine, 1965-1980.
During a search through the nuclear medicine literature, it was noticed that there was an increase in the number of journals publishing articles related to nuclear medicine as well as a change in the direction of nuclear medicine articles, moving away from morphology alone to a combination at morphology and physiology. We have attempted to document these trends via a survey of nuclear medicine journal literature for the period 1965-1980.
Atraumatic hepatic subcapsular hematoma diagnosed by Tc-99m HIDA hepatocholescintigraphy.
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Pulmonary embolism and deep venous thrombosis.
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Filling, postcholecystokinin emptying, and refilling of normal gallbladder: effects of two different doses of CCK on refilling: concise communication.
A study of 18 normal subjects was undertaken to evaluate the rapidity of gallbladder filling with Tc-99m IDA during fast, and the degree of emptying and incidence of refilling after intravenous infusion of either 20 or 40 ng/kg of octapeptide of cholecystokinin (CCK-8). During fast, the frequency of onset of gallbladder filling with Tc-99m IDA at 20, 30, 40, and 42 min was 68%, 84%, 95%, and 100%, respectively. Following CCK-8 infusion, the gallbladder mean ejection period of 11 +/- 4 (s.d.) min and ejection fraction of 40% +/- 23 were similar in subjects given either a 20 ng/kg or a 40 ng/kg dose. The frequency of onset of refilling at 20, 30, 40, and 50 min after CCK-8 was 33%, 63%, 71%, and 79%, respectively for the combined groups. At 50 min after CCK-8, all subjects given 20 ng/kg refilled, whereas only 63% of the 40-ng/kg group did so. There was no correlation between the degree of emptying (ejection fraction) and onset of refilling. We conclude that the frequency of post CCK-8 onset of gallbladder refilling, which reflects sphincter tone recovery, is widely variable, depending upon both the dose and the duration from the time of infusion of CCK-8 and should be taken into consideration if a pre-emptying procedure is adopted during hepatobiliary imaging with Tc-99m IDA agents.
Diagnosis of clinically unsuspected gallbladder perforation in an obese patient, by Tc-99m IDA cholescintigraphy.
A male Pickwickian syndrome patient was admitted to the hospital with sudden onset of abdominal pain. Physical examination was equivocal. Due to patient's ileus and morbid obesity (weight 450 lb), neither TCT scan nor ultrasound was possible. A Tc-99m PIPIDA hepatobiliary imaging study revealed intraperitoneal leakage of radioactive bile with collection of the activity in both abdominal gutters, indicating gallbladder rupture. Prompt surgery confirmed the diagnosis.
Quantitative biliary dynamics: introduction of a new noninvasive scintigraphic technique.
We used a Tc-99m-labeled hepatobiliary agent to measure the partition of hepatic bile between gallbladder and intestine in sixteen normal patients and nine patients with cholelithiasis. In normal subjects, the fractions of the hepatic bile that flow into the gallbladder and the small intestine were widely variable, with mean values of 69 +/- 7% (s.e.) and 31 +/- 7% respectively. Bile reflux into the common hepatic duct was rare, occurring during the first 2/3 of the gallbladder ejection period and only when the ejection fraction was greater than 59%. The gallbladder's mean latent period, ejection period, ejection fraction, and ejection rate were 2 +/- 1 min, 11 +/- 1 min, 59 +/- 4%, and 5.9%/min respectively. In patients with cholelithiasis, the fraction of hepatic bile flowing into the gallbladder was normal, but the ejection fraction was significantly reduced (p less than 0.005). For an equivalent dose of cholecystokinin, the gallbladder in cholelithiasis is less responsive than in normal subjects.
Measurement of gallbladder emptying sequentially using a single dose of 99mTc-labeled hepatobiliary agent.
The gallbladder emptying response to a single large (20 ng/kg) and four equally divided sequential small (5 ng/kg each) doses of octapeptide of cholecystokinin at 20-min intervals was measured in a paired study in six normal subjects noninvasively and quantitatively by a nongeometric method using a gamma camera, computer, and 99mTc-labeled hepatobiliary agent. The gallbladder mean (+/- SD) ejection fraction after a single large dose (20 ng/kg) of octapeptide of cholecystokinin was 34 +/- 24% and after four sequential small (5 ng/kg each) doses was 42 +/- 14%, 45 +/- 28%, 37 +/- 22%, and 32 +/- 27%, respectively (p greater than 0.05). The results of this study indicate that the first part of the 5 ng/kg sequential octapeptide of cholecystokinin dose is as effective as the single 20-ng/kg dose. The gallbladder emptying requires continued presence of high levels of octapeptide of cholecystokinin in the serum closer to levels that initiate contraction and in the absence of which the gallbladder ceases to empty further despite the fact it has inherent capacity to do so. Each of four equal octapeptide of cholecystokinin doses given sequentially elicits, on the average, an equal degree of emptying response. The method has potential for application in the study of the pharmacological effects of drugs on the biliary dynamics using a single dose of 99mTc-labeled hepatobiliary radiopharmaceutical.
Acute cholecystitis: the diagnostic role for current imaging tests.
Acute cholecystitis is a relatively common clinical entity characterized histopathologically by obstruction of the cystic duct due to either edema or stone or both. Thorough clinical assessment and selection of the appropriate diagnostic tests are crucial in making an early diagnosis before surgical treatment. Many diagnostic tests are available for imaging the gallbladder. Hepatobiliary imaging using technetium Tc 99m IDA is the test of choice to either exclude or confirm the diagnosis of acute cholecystitis and it carries a discriminating power greater than that of cholecystography or ultrasonography. In most patients the exclusion of the diagnosis of acute cholecystitis can be made as early as 30 minutes and the confirmation within three hours. The confirmation of acute cholecystitis by radionuclide imaging obviates the need for either cholecystography or ultrasonography.
Radiation-dose calculation for five Tc-99m IDA hepatobiliary agents.
The radiation absorbed doses from five commercially available hepatobiliary agents--Tc-99m-tagged analogs of IDA (EIDA, PIPIDA, HIDA, PBIDA, DISIDA) have been calculated from biokinetic data in 41 normal subjects. Serial gamma images, with blood and urine samples, were obtained to calculate cumulated radioactivity in the source organs: blood, kidney, bladder, liver, gallbladder, and intestines. The critical organ was the gallbladder, with an absorbed-dose range of 690 to 780 mrad/mCl. Absorbed doses for other target organs were: upper large intestine 320 to 370 mrad/mCi, lower large intestine 210 to 240, small intestine 170 to 200, liver 65 (DISIDA) to 130 (PBIDA), ovaries 63 to 72, and urinary bladder wall 23 (PBIDA) to 36 (EIDA). The radiation absorbed dose was largely independent of changes in chemical structure except in (a) the liver, where absorbed dose varied by a factor of two in proportion to the rate of excretion of the IDA agent from the liver, and (b) the urinary bladder, where absorbed dose varied by a factor of 1.6 because of differences in rate of excretion. When the stimulus for gallbladder emptying is changed from whole-meal ingestion to cholecystokinin injection, the absorbed dose to the gallbladder increases to approximately 1 rad/mCi; if no gallbladder emptying is assumed, its absorbed dose increases to approximately 1.9 rad/mCi. In the absence of contraindication, the gallbladder absorbed dose may thus be decreased by inducing gallbladder emptying at the end of the imaging study.
Tumor uptakes and organ distributions of gallium-67 oxalate, ligand bonded to proteins in rodents.
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Quantitative scintigraphy of sacroiliac joints: effects of age, gender, and laterality.
The effects of age, gender, and laterality on sacroiliac/sacral ratios obtained during quantitative joint imaging were assessed in 97 nonarthritic control subjects. For the entire group, the right sacroiliac-to-sacral mean ratio of 1.27 in 54 males was significantly higher (p less than 0.02) than the right mean ratio of 1.18 in 53 females. In both genders the right joint ratio tended to be higher than the left in all age groups. The difference in mean ratio between the two joints was wider for males than for females. The age did not affect the joint ratio in either gender. It is concluded that the range of normal sacroiliac-to-sacral ratios are different for males and females and should be taken into account during a quantitative sacroiliac joint imaging examination.
Unilateral hydrothorax secondary to ascites demonstration by a noninvasive radionuclide imaging technique.
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Radionuclide ejection fraction: a technique for quantitative analysis of motor function of the human gallbladder.
A new noninvasive technique for the measurement of the gallbladder evacuation quantitatively is described. By using a radioactive bile marker [99mTc]HIDA, the evacuation of the gallbladder is measured nongeometrically in terms of ejection fraction (fractional bile volume emptied from the gallbladder) and ejection rate (dv/dt). The counts and volume in an in vitro gallbladder phantom under pinhole collimator geometry show a linear relationship (r = 0.998) enabling the replacement of gallbladder bile volume by bile counts before and after evacuation. The counts ejection-fraction shows a high degree of correlation (r = 0.998) with the measured-volume method. The movement of the gallbladder during respiration does not effect the measurement of ejection fraction. The technique allows simultaneous imaging and quantitation, and it is highly reproducible, carrying an interobserver and reproducibility mean error of 5%. This technique is suitable for studying the motor functions of the gallbladder and the effects of various pharmacologic agents on its evacuation. The clinical usefulness of the technique requires further testing.