Patterns of single photon emission tomography (SPECT) among patients with dementia in the memory clinic at Siriraj Hospital.

OBJECTIVE: The authors hypothesized that there is a pattern difference in cerebralperfusion of the 99-Technitium L, L-ethyl cysteinate dimer Single Photon Emission Computer Tomography (99-Tc ECD SPECT) between mild and moderate to severe dementia. MATERIAL AND METHOD: The authors reported a retrospective study in the Memory Clinic, Siriraj Hospital between January 2001 and October 2003 including only patients with Alzheimer's disease, vascular dementia, and mixed dementia. Clinical dementia rating (CDR) was used to document dementia severity. Patterns of hypoperfusion were classified into no definite hypoperfusion, regional hypoperfusion, and diffused hypoperfusion. RESULTS: One hundred and seven patients were included in the present study. Only mean Thai Mental State Examination (TMSE) score was different between the two groups. There was no significant correlation between pattern of hypoperfusion in brain SPECT and severity of dementia. CONCLUSION: The authors cannot demonstrate the pattern of hypoperfusion of 99-Tc ECD SPECT among patients' difference in dementia severity.

Bile leak detection by radionuclide scintigraphy.

INTRODUCTION: Bile leak after liver injury has been reported to be a complication associated with significant mortality. Tc99m-IDA (Tc: Technetium) nuclear scan allows rapid and noninvasive diagnosis of bile leak. OBJECTIVE: An accidental case was referred for the detection of suspicious bile leak. METHODS: The ultrasound could not detect any abnormality. Dynamic Hepatobiliary Scintigraphy (DHBS) using radiolabeled tracer was performed. RESULTS: DHBS promptly detected the site of leak. CONCLUSION: This technique should be opted because it has been found to be quite sensitive, specific and accurate for detecting the bile leak, whereas, Ultrasound and CT imaging are less sensitive and nonspecific. Though, they are initially helpful in determining the presence of abdominal fluid collections, they are unable to differentiate between a seroma, lymphocele, hematoma or bile leak. Hepatobiliary scintigraphy is more accurate because it can demonstrate continuity of these fluid collections with the biliary tree. Further, hepatobiliary scintigraphy can provide real-time assessment of hepatocytes function and bile progression from the liver to the intestine.

Imaging using Tc99m-tetrofosmin for the detection of the recurrence of brain tumour: a comparative study with Tc99m-glucoheptonate.

BACKGROUND: In the past "blood-brain barrier" agents such as Tc99m-glucoheptonate were routinely used for the diagnosis of brain tumours. Of late, agents used for studying myocardial perfusion namely, Tc99m-tetrofosmin, Thallium-201, and Tc99m-sestamibi have replaced the "blood-brain barrier agents " when imaging is undertaken for the detection of the recurrence of brain tumours. However, the incremental diagnostic information provided by Tc99m-tetrofosmin when compared with a blood brain barrier agent in the diagnosis of recurrent brain tumour has not been evaluated till date. AIMS: The study was carried out to substantiate whether Tc99m-tetrofosmin provides any incremental diagnostic information not provided by the blood brain barrier agent Tc99m-glucoheptonate. MATERIAL AND METHODS: Brain SPECT scans were performed using Tc99m-tetrofosmin and Tc99m-glucoheptonate in 126 patients of recurrent brain tumour. Bio-distribution and uptake properties of both the tracers were analysed by measuring relative uptake of both the tracers in tumour compared to background (T/B ratio), nasopharynx (T/N ratio) and scalp (T/S ratio). STATISTICAL ANALYSIS: Descriptive statistics were calculated for each variable. Pearson's correlation coefficient was applied to see agreement of the continuous variables. Paired t test was used to evaluate the difference between two means. RESULTS: Uptake properties of both the tracers were analysed in 105 patients in whom both Tc99m-tetrofosmin and Tc99m-glucoheptonate showed concentration. The remaining 21 patients in whom the tumour mass did not show Tc99m-tetrofosmin concentration were excluded from the study. Mean T/B ratio, T/N ratio and T/S ratio was 5.83 + 2.09 and 5.99 + 2.26, 0.53 + 0.21 and 0.55 + 0.22 and 1.11 + 0.60 and 1.26 + 0.52 for Tc99m-tetrofosmin and Tc99m-glucoheptonate respectively. No statistically significant difference between T/B ratio and T/N ratio of Tc99m-tetrofosmin and Tc99m-glucoheptonate was found; p values were 0.25 and 0.83 respectively. However there was significant difference (P=0.006) between the T/S ratio of Tc99m-tetrofosmin and that of Tc99m-glucoheptonate. CONCLUSION: Tc99m-tetrofosmin does not provide any incremental diagnostic information not provided by the blood brain barrier agent Tc99m-glucoheptonate.

Evaluation of single photon emission computerised tomography (SPECT) using Tc99m-tetrofosmin as a diagnostic modality for recurrent posterior fossa tumours.

BACKGROUND: Brain Single Photon Emission Computerised Tomography (SPECT) has been established as a potentially useful tool for the assessment of recurrent brain tumours. Though brain SPECT is exquisitely sensitive in detecting viable tumour tissue in the supratentorial region, its efficacy has not been evaluated till date in case of infratentorial posterior fossa tumours. AIM OF THE STUDY: To evaluate the diagnostic utility of brain SPECT in differentiating recurrence of tumour from post-radiation gliosis in the posterior fossa of the brain. SUBJECTS AND METHODS: Twenty-one patients with primary malignant posterior fossa brain tumour were evaluated by brain SPECT with Tc99m-Tetrofosmin as the tumour-seeking agent. Clinical behaviour of the tumour observed for a minimum period of one year after the SPECT study was taken as the gold standard. STATISTICAL ANALYSIS: The Chi-square test has been used to note the significance of the association between the clinical outcome and the SPECT finding. In addition, the sensitivity and specificity of brain SPECT were also calculated. RESULT: Brain SPECT in 4 patients revealed increased tracer concentration over the primary tumour bed, which was consistent with recurrent tumour. The clinical course was consistent with tumour recurrence in 13 of the 21 patients, which included 3 patients with positive SPECT study and 10 patients with negative SPECT study. Brain SPECT revealed recurrent tumour in 4 patients whereas clinical follow-up suggested recurrence in 13 patients. The clinical course was consistent with radiation necrosis in the remaining 8 patients. In 1 brain SPECT positive patient the clinical course was consistent with post-radiation gliosis. CONCLUSION: This study demonstrates that brain SPECT is not a sensitive diagnostic modality to differentiate recurrent tumour from post-radiation gliosis in the posterior fossa of the brain.

Hepatobiliary clearance of labelled mebrofenin in normal and D-galactosamine HCl-induced hepatitis rats and the protective effect of turmeric extract.

This study was carried out to see the hepatobiliary clearance of 99m Tc-Mebrofenin radiopharmaceutical in D-galactosamine induced hepatic rats. Furthermore, protective effect of turmeric extract has been studied in these hepatitis rats. Hepatitis was induced with intraperitoneal injection of D-galactosamine (400 mg/kg b. wt) in these rats. 1% turmeric extract was given along with their normal diet for 15 days. Turmeric extract treatment significantly increased the hepatic uptake of radioactivity and accelerated the excretion of 99m Tc-Mebrofenin as compared to control rats. (P < 0.001). In D-galactosamine administered rats, a significant delay was observed in 99m Tc-Mebrofenin excretion as compared to controls. However, D-galactosamine administered rats, pretreated with turmeric extract or concurrently treated with turmeric extract showed a near normal pattern of 99m Tc-Mebrofenin excretion. Hence, it can be suggested that turmeric extract may improve the liver function by detoxification.

Detecting protein losing enteropathy by Tc-99m dextran scintigraphy: a novel experience.

OBJECTIVE: To evaluate protien using enteropathy by Tc-99m dextran scintigraphy. METHODS: Methods for detecting protein loss from the intestine revolve around fecal nitrogen excretion, the clearance of alpha-1 antitrypsin in stools and by endoscopic biopsy. RESULT: The diagnosis of protein-losing enteropathy (PLE) can also be established by a scintigraphic method that is noninvasive, simple and requires no patient preparation or motivation. This diagnostic modality can also delineate the site of protein loss, thereby offering a targeted approach, and if need be, surgery. Radiolabelling of a non-protein, noncolloidal, nonparticulate and biofriendly molecule like dextran with Technetium-99m for imaging enteric protein loss was utilized in imaging eight children with PLE. CONCLUSION: The results were encouraging. The authors advocate the use of this diagnostic tool in identifying patients with PLE, particularly in the pediatric age group.

99mTc-labeled field bean protease inhibitor can function as an efficient tumor detecting agent.

Purified field bean protease inhibitor (FBPI) was labeled with 99mTcO4- to ascertain its ability to locate tumors in tumor-bearing rat models. The labeling was done with Sn2+ as a reducing agent and the yield was 95%. It was stable for 2 hr at ambient temperature. The biodistribution study of the intravenously injected radiolabeled FBPI in normal Wistar rats at various time intervals showed a rapid blood clearance from the systemic circulation (approximately 5hr). The complex was predominantly excreted through the renal and the hepatobiliary systems. In vivo distribution and scintiimaging of 99mTc-FBPI were carried out in rats bearing carcinogen-induced mammary tumor or transplanted C6-gliomas. The results obtained were compared with conventional tumor-seeking radiopharmaceuticals such as 99mTc-(V)dimercaptosuccinic acid (DMSA), 201Thallous chloride (TICI) and 99mTc-Citrate. The tumor to muscle (T/M) ratios obtained with 99mTc-FBPI in rat C6 glioma was nearly 2 to 5-fold higher than obtained with all the three conventional tumor-seeking agents. The T/M ratio obtained with 99mTc-FBPI in rat mammary tumor on the other hand appeared to be 2-3-fold higher than noted with 99mTc(V)-DMSA and 201TlCl. The ratio was however comparable with that obtained with 99mTc-Citrate. The study indicated that 99mTc-FBPI has the specific potentials for imaging gliomas and possibly other tumors as well.

Role of biliary scintigraphy in management of bile leak.

BACKGROUND: Endoscopic biliary drainage is effective in the management of patients with postoperative bile leak. Evidently, it cannot be used in patients with completely tied-off common bile duct (CBD). AIM: To ascertain whether biliary excretion scintigraphy could reliably detect patients with tied-off CBD so that endoscopic retrograde cholangiography (ERC), an invasive test, could be avoided. METHODS: Twelve patients with active bile leak (11 postcholecystectomy, one posttraumatic), in whom the biliary system was imaged by both 99m technetium mebrofenin biliary scintigraphy and ERC, were evaluated. RESULTS: Bile leak was demonstrated in all the 12 patients by scintigraphy. In six of these, there was no visualization of radionuclide activity in the intestines; in three of these six patients, ERC showed a patent CBD potentially amenable to endoscopic drainage, whereas in the remaining three, there was complete obstruction presumably due to CBD tie-off during surgery. CONCLUSION: Biliary excretion scintigraphy is unreliable for detecting complete biliary obstruction in patients with bile leak.

Radionuclide studies in the evaluation of urinary tract infections.

OBJECTIVE: To estimate the prevalence of vesicoureteral reflux (VUR) and renal scarring in children presenting with culture proven urinary tract infections (UTI). DESIGN: Descriptive study. SETTING: Tertiary care hospital-based study. SUBJECTS: Thirty-two children with proven UTI were evaluated by means of an abdominal ultrasonogram (USG), Technetium-99m Dimercapto Succinic Acid (DMSA) scan and Direct Radionuclide Cystography (DRCG). A micturating cystourethrogram (MCU) was performed to rule out any structural abnormality and to grade VUR. RESULTS: A total of 64 renal units in 32 children were evaluated. DMSA scan showed scarring in 27 renal units (42.2%) in 16 patients. Bilateral renal scarring was more common in older (> 2 yr) children as compared to younger ones (89% Vs 43%; p < 0.05). USG detected abnormalities in 13 renal units (20.3%) in 7 cases. VUR was detected in 37.5% of children of all age group by DRCG. In contrast, MCU showed evidence of VUR in only 13/20 renal units with a sensitivity of 65% as compared to DRCG and did not pick up any additional VUR that could have been missed on the DRCG. Only 3/9 in < 2 yr, in contrast to 10/11 in > 2 yr were positive for VUR on MCU (p < 0.05). However, MCU detected evidence of cystitis in 3 children and a bladder diverticulum in one patient. CONCLUSION: Wherever available, DMSA scan should be considered as a part of the first line investigations in any patient presenting with UTI. DRCG can also be performed in the same sitting to screen for the presence of reflux particularly for girls.

Cholescintigraphic detection of biliary leaks.

We report four cases in whom post-traumatic or post-surgical biliary leak was detected using dynamic 99mtechnetium-iminodiacetic acid (IDA) cholescintigraphy. This technique is a non-invasive, safe, simple and sensitive method of documenting the presence, location and extent of biliary leaks. Further, it can be repeated and hence, is useful in evaluating the response to treatment. Surgery is indicated when a moderate extravasation of labeled bile suggests that the leak is the chief pathway of bile drainage, with relatively little bile entering the intestine.

Scintigraphic right-to-left liver lobe ratio and liver-to-spleen ratio in cirrhosis and non cirrhotic liver diseases.

Various criteria are used together for the scintigraphic diagnosis of cirrhosis as no single criterion may be reliable. However, low right-to-left hepatic lobe uptake ratio has been reported to be sensitive and specific for alcoholic cirrhosis. A low liver-to-spleen uptake ratio has also been reported in various hepatocellular disorders. We tested these ratios in patients with cirrhosis and non cirrhotic causes of portal hypertension. The right-to-left lobe uptake ratio was significantly lower (1.59 +/- 1.23 vs 2.36 +/- 0.63 in normals; p = 0.037) in only Child's C alcoholic cirrhosis, but the sensitivity of this ratio was low (40%) even in this subgroup of cirrhosis (mean +/- SD 1.72 +/- 1.08) as against 1 of 10 patients with non cirrhotic portal hypertension (3.57 +/- 1.33; p = 0.0005). We conclude that the right-to-left hepatic lobe uptake ratio is not a discriminatory scintigraphic sign in liver disease. A low liver-to-spleen uptake ratio can distinguish cirrhosis from non cirrhotic causes of portal hypertension.

Thoracic stomach: comparative evaluation of endoscopy, gastric aspirate analysis and hepatobiliary scintigraphy in the diagnosis of duodeno-gastric reflux.

Twenty patients with thoracic stomach were subjected to hepatobiliary scintigraphy for the diagnosis of duodenogastric reflux. The results of the radionuclide studies were correlated with those of endoscopy and biochemical estimation of total intragastric bile acid. Hepatobiliary scintigraphy was found to be more sensitive (91.6%) and accurate (95%) than endoscopy (25% and 55% respectively) and biochemical estimation of total intragastric bile acid content (66.6% and 80% respectively). Being noninvasive and physiological, radionuclide study appears suitable for routine clinical use in the diagnosis of duodeno-gastric reflux.