99mTc colloid and 99mTc IDA imagings in diffuse hepatic disease

Spatially resolved assessment of hepatic function using 99mTc-IDA SPECT

PURPOSE

99mTc-iminodiacetic acid (IDA) hepatobiliary imaging is usually quantified for hepatic function on the entire liver or regions of interest (ROIs) in the liver. The authors presented a method to estimate the hepatic extraction fraction (HEF) voxel-by-voxel from single-photon emission computed tomography (SPECT)∕CT with a 99mTc-labeled IDA agent of mebrofenin and evaluated the spatially resolved HEF measurements with an independent physiological measurement.

METHODS

Fourteen patients with intrahepatic cancers were treated with radiation therapy (RT) and imaged by 99mTc-mebrofenin SPECT before and 1 month after RT. The dynamic SPECT volumes were with a resolution of 3.9 × 3.9 × 2.5 mm(3). Throughout the whole liver with approximate 50 000 voxels, voxelwise HEF quantifications were estimated and compared between using arterial input function (AIF) from the heart and using vascular input function (VIF) from the spleen. The correlation between mean of the HEFs over the nontumor liver tissue and the overall liver function measured by Indocyanine green clearance half-time (T1∕2) was assessed. Variation of the voxelwise estimation was evaluated in ROIs drawn in relatively homogeneous regions of the livers. The authors also examined effects of the time range parameter on the voxelwise HEF quantification.

RESULTS

Mean of the HEFs over the liver estimated using AIF significantly correlated with the physiological measurement T1∕2 (r = 0.52, p = 0.0004), and the correlation was greatly improved by using VIF (r = 0.79, p < 0.0001). The parameter of time range for the retention phase did not lead to a significant difference in the means of the HEFs in the ROIs. Using VIF and a retention phase time range of 7-30 min, the relative variation of the voxelwise HEF in the ROIs was 10% ± 6% of respective mean HEF.

CONCLUSIONS

The voxelwise HEF derived from 99mTc-IDA SPECT by the deconvolution analysis is feasible to assess the spatial distribution of hepatic function in the liver.

Radiopharmaceuticals drug interactions: a critical review

Radiopharmaceuticals play a critical role in modern medicine primarily for diagnostic purposes, but also for monitoring disease progression and response to treatment. As the use of image has been increased, so has the use of prescription medications. These trends increase the risk of interactions between medications and radiopharmaceuticals. These interactions which have an impact on image by competing with the radiopharmaceutical for binding sites for example can lead to false negative results. Drugs that accelerate the metabolism of the radiopharmaceutical can have a positive impact (i.e. speeding its clearance) or, if repeating image is needed, a negative impact. In some cases, for example in cardiac image among patients taking doxirubacin, these interactions may have a therapeutic benefit. The incidence of drug-radiopharmaceuticals adverse reactions is unknown, since they may not be reported or even recognized. Here,we compiled the medical literature, using the criteria of a systematic review established by the Cochrane Collaboration, on pharmaceutical-drug interactions to provide a summary of documented interactions by organ system and radiopharmaceuticals. The purpose is to provide a reference on drug interactions that could inform the nuclear medicine staff in their daily routine. Efforts to increase adverse event reporting, and ideally consolidate reports worldwide, can provide a critically needed resource for prevention of drug-radiopharmaceuticals interactions.

Density histogram analysis of unenhanced hepatic computed tomography in patients with diffuse liver diseases

OBJECTIVE

The aim of the study was to assess the potential of density histogram analysis of unenhanced hepatic computed tomography (CT) in the diagnosis and differentiation of diffuse liver diseases.

METHODS

Twenty-six patients with normal liver parenchyma, 35 patients with diffuse steatosis, 14 patients with acute steatohepatitis, 15 patients with active alcoholic cirrhosis, 23 patients with inactive alcoholic cirrhosis, 15 patients with virus-induced cirrhosis, and 8 patients with hemochromatosis underwent unenhanced hepatic CT. All diffuse liver diseases and the absence of diffuse liver disease were histologically proven. Quantitative analysis of unenhanced liver parenchyma was performed in each patient.

RESULTS

The hepatic density histogram showed no significant differences in kurtosis and skewness between the groups (P > 0.05). Except for steatosis, active alcoholic cirrhosis, and hemochromatosis, diffuse liver diseases led to similar densities of liver parenchyma in unenhanced hepatic CT.

CONCLUSION

A reliable diagnosis and differentiation of diffuse liver diseases on the basis of density histogram analysis is not possible.

Gastric tone variations during gastric infusion of fiber-supplemented formulas

BACKGROUND AND AIM

Despite gastric feeding being a common method of artificial nutritional support, little is known about the effects of enteral nutrition on fundic motor function. The objective of this study was to assess variations of fundic tone and their relation to antroduodenal motility before, during and after nasogastric feeding supplemented or not with fibers.

METHOD

Double-blinded studies were performed in random order with the three different diets (2100 kJ) in eight volunteers: fiber free (FF), insoluble fiber (IF) or mixed fiber (MF). Fundic tone was recorded by barostat concomitantly with antroduodenal manometry.

RESULTS

Before the infusion, seven spontaneous fundic relaxations occurred during the 24 studies. Concomitantly or less than 2 min before these relaxations, phase III of the migrating motor complex (MMC) with a duodenal onset was recorded. Only the 17 studies without spontaneous fundic relaxation (4 FF, 6 MF, 7 IF) were suitable for the assessment of fundic response to infusion. Disappearance of the volume waves at the beginning and during the whole infusion was observed in 11/17 studies (FF 50%, MF 66% and IF 71%, NS), but a proximal gastric relaxation following the beginning of the infusion occurred in only three individuals, one with the FF and two with IF. When it occurred, fundic relaxation was observed within 2 min and was not different from those observed spontaneously.

CONCLUSION

Gastric infusion of a polymeric diet, supplemented or not with fiber, did not promote fundic relaxation in most of the cases but often induced a disappearance of gastric volume waves.

Effects of exercise on gastric volume and pH in the proximal portion of the stomach of horses

OBJECTIVE

To assess effects of exercise on a treadmill with changes in gastric volume and pH in the proximal portion of the stomach of horses.

ANIMALS

3 healthy adult horses.

PROCEDURE

A polyester bag of approximately 1,600 mL was placed into the proximal portion of the stomach of each horse via a nasogastric tube. Changes in bag volume, determined by an electronic barostat, were recorded before, during, and after a training session on a treadmill with and without prior withholding of food. In separate experiments, pH in the proximal portion of the stomach was continuously recorded during exercise for fed and food-withheld conditions. Finally, changes in intra-abdominal and intragastric pressure were simultaneously recorded during a training session.

RESULTS

Bag volume rapidly decreased to nearly zero during trotting and galloping. Conversely, a return to walking resulted in a sharp increase in volume and a return to pre-exercise values. Intragastric and intra-abdominal pressures increased almost in parallel with walking, trotting, galloping, and galloping on a slope. Gastric pH decreased rapidly to < 4 at the beginning of walking, continued to decrease during trotting and galloping, and remained low until a return to walking.

CONCLUSIONS AND CLINICAL RELEVANCE

Increased intra-abdominal pressure during intense exercise in horses causes gastric compression, pushing acidic contents into the proximal, squamous-lined region of the stomach. Increased duration of acid exposure directly related to daily duration of exercise may be the reason that squamous lesions tend to develop or worsen when horses are in intensive training programs.

The role of the barostat in human research and clinical practice

BACKGROUND

The barostat is a recently developed device used to study the physiology and pathophysiology of the motor and sensory functions of the gastrointestinal tract. It can monitor volume changes while maintaining a set constant pressure and deliver controlled distensions of gastrointestinal organs. Simultaneously, motility and visceral perception may be assessed. The barostat has contributed to the understanding of physiological processes in the gastrointestinal tract with regard to regulation of tone, compliance, enteric reflexes, sensation and processing of signals to and from the gut. In addition, the barostat has been used to study various gastrointestinal disorders. In functional bowel disorders, objective abnormalities in visceral sensitivity and enteric reflexes have been demonstrated. Numerous other diseases, gastrointestinal in origin as well as systemic diseases affecting the gut, have been studied. In the near future, the barostat may become a clinically useful tool for the objective diagnosis of motor and sensitivity disorders of the gut and for monitoring the effectiveness of therapy.

Subacute hepatic failure: diagnosis of exclusion?

Subacute hepatic failure has been a controversial diagnosis ever since it was first identified more than 15 years ago. The Working Committee on Subacute Hepatic Failure has attempted to redefine this entity in which exclusion of preexisting cirrhosis on liver biopsy has been emphasized. Acute viral hepatitis in a patient with asymptomatic chronic liver disease (e.g., hepatitis B or C, Wilson's disease) can be misdiagnosed as subacute hepatic failure in the absence of a liver biopsy. This situation is common in developing countries where the prevalence of feco-orally transmitted (hepatitis A [<20 years] and hepatitis E [>20 years]) and parenterally transmitted (hepatitis B) viruses is high. To obtain and interpret liver biopsy specimens in such a situation is difficult and hazardous, and hence rarely performed. Acute viral hepatitis in a patient with asymptomatic chronic liver disease should be carefully looked for and excluded, especially in developing countries, before a diagnosis of subacute hepatic failure is confirmed.

Gastric relaxation in response to a soup meal in healthy subjects. A study using a barostat in the proximal stomach

BACKGROUND

Meal-induced relaxation of the proximal stomach can be investigated by means of a barostat. Using a standard liquid meat soup that elicits symptoms and a wide antrum in patients with functional dyspepsia, we aimed at finding the best meal size and fat load for studying gastric relaxation.

METHODS

In the first trial 200 ml and 500 ml meat soup (1 g fat/200 ml) was given to six healthy individuals. In the second trial a constant volume of soup (200 ml) containing graded amounts of fat (1, 10, and 20 g/200 ml) was given to seven healthy individuals. Gastric relaxation was investigated for 1 h after consumption of the soup. A sagittal cross-sectional antral was assessed ultrasonographically every 10 min, and abdominal discomfort was scored.

RESULTS

Overall, a positive response (volume increase of 30 ml or more within 5 min after consumption of the meal) was found in 26 of 30 (87%) investigations. Individual maximal responses ranged from 38 to 482 ml (mean, 180 ml +/- 128). Area under the time-volume curve (AUC) was similar after 200 and 500 ml soup (mean, 100 ml/30 min and 107 ml/30 min, respectively). AUC increased with increasing fat content, with a significant difference between the low-fat and high-fat meal (p < 0.05). The barostat bag induced fed-state antral contractions in most individuals (p < 0.001). There was a negative correlation between AUC and postprandial abdominal discomfort (p = 0.04).

CONCLUSIONS

The barostat is a sensitive technique for detecting gastric relaxation, also in response to our standard meat soup meal. The postprandial relaxation response in healthy individuals in dependent on the fat content of the meal. The barostat bag may alter gastric motor activity. Abdominal discomfort after soup ingestion may be related to poor gastric relaxation.