An innovative technique for electronic transport model of group-III nitrides

An optimized empirical pseudopotential method (EPM) in conjunction with virtual crystal approximation (VCA) and the compositional disorder effect is used for simulation to extract the electronic material parameters of wurtzite nitride alloys to ensure excellent agreement with the experiments. The proposed direct bandgap results of group-III nitride alloys are also compared with the different density functional theories (DFT) based theoretical results. The model developed in current work, significantly improves the accuracy of calculated band gaps as compared to the ab-initio method based results. The physics of carrier transport in binary and ternary nitride materials is investigated with the help of in-house developed Monte Carlo algorithms for solution of Boltzmann transport equation (BTE) including nonlinear scattering mechanisms. Carrier–carrier scattering mechanisms defined through Coulomb-, piezoelectric-, ionized impurity-, surface roughness-scattering with acoustic and intervalley scatterings, all have been given due consideration in present model. The direct and indirect energy bandgap results have been calibrated with the experimental data and use of symmetric and asymmetric form factors associated with respective materials. The electron mobility results of each binary nitride material have been compared and contrasted with experimental results under appropriate conditions and good agreement has been found between simulated and experimental results.

Effect of Mirtazapine on Gastric Emptying in Patients with Cancer-associated Anorexia

BACKGROUND/AIMS

The tetracyclic antidepressant mirtazapine is widely used in cancer patients suffering from anorexia. Although it is known to restore appetite, the exact mechanism remains unknown. The aim of the study was to evaluate if mirtazapine has any effect on gastric emptying in patients suffering from cancer-related anorexia.

MATERIALS AND METHODS

Solid-meal gastric-emptying study using radiolabeled meal was performed in 28 patients suffering from cancer anorexia once at baseline and repeated after 15 days of mirtazapine therapy.

RESULTS

At baseline, only 7 (25%) patients had normal gastric motility (emptying >70% at 3 h postingestion) whereas after treatment, 18 (64.2%) patients achieved this limit. Mean % gastric emptying increased from 55.2% ±21.0% to 68.9% ±21.3% (P < 0.001). Mean gastric emptying time (t_1/2) before intervention was 314.7 ± 421.0 min which decreased to 116.0 ± 106.7 min after intervention. Results were further analyzed by dividing the patients into two groups based on baseline gastric-emptying study. Group A (normal gastric emptying) consisted of seven patients, mean % gastric emptying at baseline and postintervention was 75.0% ±5.25% and 87.57% ±5.94%, respectively (P < 0.018). Group B (delayed gastric emptying) consisted of 21 patients, mean % gastric emptying at baseline and postintervention was 48.71% ±18.82% and 62.76% ±16.86%, respectively (P < 0.001).

CONCLUSION

Mirtazapine significantly improves gastric emptying in patients of prostate and breast cancer suffering from cancer-associated anorexia.

Abstract P3-01-06: Sentinel lymph node biopsy after NACT: Results of a validation study in large/locally advanced breast cancer patients

Background:

Sentinel lymph node biopsy (SLNB) is the current standard of care for surgical staging of clinically node negative axilla (N0) early breast cancer patients undergoing primary surgery. SLN- identification rate (IR) of 90% and SLN- false negative rate (FNR) of 10% are considered minimum acceptable indices for SLNB. Its role in staging axillae in patients undergoing post-NACT surgery is somewhat unclear. In India, and most low-and-middle income countries, large operable breast cancers (LOBC) and locally advanced breast cancers (LABC) constitute a large proportion of breast cancer patients treated. These patients are usually are treated with NACT, followed by surgery and radiation therapy. In a prospective validation SLNB study, we investigated the accuracy of SLNB in staging post-NACT N0 axilla in a patient cohort that were LOBC or LABC at the time of initial presentation.

Methods:

Hundred consenting non-inflammatory LOBC/LABC patients (mean age 49.3+8.6; index stage T3,N0-1=21; T4b,N0-1=33; T1-3,N2a=24; T4b,N2a=22) who were N0 after NACT at time of surgery (Breast conservation surgery in 19, Mastectomy in 81) were included. Majority had Infiltrating ductal carcinoma (n=87), and grade II/III tumors (n=93); 45 were hormone receptor positive (+), 29 had HR negative (-) HER2(+); and 26 had triple negative breast cancer on IHC sub-typing. Commonest NACT regimen used was Anthracycline followed by taxanes in 83. SLNB was performed using low-cost methylene-blue and 99mTc-Antimony-colloid, which were produced in-house using well standardized protocols, with clearance of the institutional ethics committee. Irrespective of the SLN histology, a complete axillary dissection (ALND) was carried out in all. SLN-IR and SLN-FNR were calculated, comparing the histological status of the SLN and the ALND specimen. Factors predicting non-identified SLN and false negative SLN were evaluated in uni-variate and multi-variate analysis.

Results:

With a combination of methylene blue dye and radiopharmaceutical, the SLN-IR was 81%. Mean number of SLN removed was 2.4+/-1.02. Mean number of nodes removed at ALND was 13.3+/-2.2. SLN-IR varied significantly (p&lt;0.05) per index stage, and were- 90.4% in T3,N0-1; 84.4% in T4b,N0-1; 83.3% in T1-3,N2a; and 63.6% in T4bN2a. The FNR was 17.3% for the whole cohort. FNR varied significantly (p&lt;0.05) per index stage, and were- 8.3% in T3,N0-1; 14.9% in T4b,N0-1; 22.2% in T1-3,N2a; and 30% in T4bN2a. Factors found predictive of non-identified SLN were tumor stage T4b, nodal stage N2a, extra-nodal spread, and LVI. Factors found predictive of FNR SLN were tumor stage T4b, nodal stage N2a, and extra-nodal spread.

Conclusions:

Considering SLN-IR of 90% and SLN-FNR of 10% as acceptable standards, SLNB in post-NACT N0 patients undergoing surgery was not found robust in staging the axilla, with the exception of patients with index stage T3,N0-1 who had SLN-IR of 90.4% and SLN-FNR of 8.3%. Patients with (pre-NACT) skin involvement(T4b), matted axillary nodes(N2a) and LVI are fraught with high-risk of non-identification and false-negative SLNB.

Citation Format: Agarwal G, Gambhir S, Lal P, Rajan S, Krishnani N, Mishra A, SabaRetnam M, Agarwal A, Chand G, Verma AK, Mishra SK, Kumari N, Agrawal V, Kheruka SC. Sentinel lymph node biopsy after NACT: Results of a validation study in large/locally advanced breast cancer patients. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-01-06.

Processable conducting graphene/chitosan hydrogels for tissue engineering

Electrically conductive, mechanically improved graphene/chitosan/lactic acid composites were synthesised and could be easily processed into multi-layer scaffolds using additive fabrication techniques.

A study to improve the image quality in low-dose computed tomography (SPECT) using filtration

BACKGROUND

The output of the X-ray tube used in computed tomography (CT) provides a spectrum of photon energies. Low-energy photons are preferentially absorbed in tissue; the beam spectrum shifts toward the higher energy end as it passes through more tissue, thereby changing its effective attenuation coefficient and producing a variety of artifacts (beam-hardening effects) in images. Filtering of the beam may be used to remove low-energy photon component. The accuracy of attenuation coefficient calculation by bilinear model depends highly upon accuracy of Hounsfield units. Therefore, we have made an attempt to minimize the beam-hardening effects using additional copper filter in the X-ray beam. The quantitative evaluation were made to see the effect of additional filters on resulting CT images.

MATERIALS AND METHODS

This study was performed on dual-head SPECT (HAWKEYE 4, GE Healthcare) with low-dose CT which acquires images at peak voltages of 120/140 kV and a tube current of 2.5 mA. For the evaluation of image quality, we used CT QA Phantom (PHILIPS) having six different density pins of Water, Polyethylene, Nylon (Aculon), Lexan, Acrylic (Perspex) and Teflon. The axial images were acquired using copper filters of various thicknesses ranging from 1 to 5 mm in steps of 1 mm. The copper filter was designed in such a manner that it fits exactly on the collimator cover of CT X-ray tube. Appropriate fixation of the copper filter was ensured before starting the image acquisition. As our intention was only to see the effect of beam hardening on the attenuation map, no SPECT study was performed. First set of images was acquired without putting any filter into the beam. Then, successively, filters of different thicknesses were placed into the beam and calibration of the CT scanner was performed before acquiring the images. The X-ray tube parameters were kept the same as that of unfiltered X-ray beam. All the acquired image sets were displayed using Xeleris 2 (GE Healthcare) on a high-resolution monitor. Moreover, Jaszak's SPECT Phantom after removing the spheres was used to see the different contrast intensities by inserting the different contrast materials of iodine and bismuth in water as background media. Images were analyzed for visibility, spatial resolution and contrast.

RESULTS

Successive improvement in the image quality was noticed when we increased the filter thickness from 1 to 3 mm. The images acquired with 3-mm filter appeared almost with no artifacts and were visibly sharper. Lower energy photons from X-ray beam cause a number of artifacts, especially at bone-tissue interfaces. Additional filtrations removed lower energy photons and improved the image quality. Degradation in the image quality was noticed when we increased the filter thickness further to 4 and 5 mm. This degradation in image quality happened due to reduced photon flux of the resulting X-ray beam, causing high statistical noise. The spatial resolution for image matrix of 512 × 512 was found to be 1.29, 1.07, 0.64 and 0.54 mm for without filter, with 1, 2 and 3 mm filters, respectively. The image quality was further analyzed for signal-to-noise ratio (SNR). It was found to be 1.72, 1.78, 1.98 and 1.99 for open, with 1, 2 and 3 mm filters respectively. This shows that 3-mm filter results in an improvement of 15.7% in SNR.

CONCLUSION

On the basis of this study, we could conclude that use of 3-mm copper filter in the X-ray beam is optimal for removing the artifacts without causing any significant reduction in the photon flux of the resulting X-ray beam. We also propose that as artifacts have been removed from the images, the value of Hounsfield units will be more accurate and hence the value of attenuation coefficients lead to better contrast and visualization of SPECT images.

Patient-maintained propofol sedation using reaction time monitoring: a volunteer safety study

Previous volunteer studies of an effect-site controlled, patient-maintained sedation system using propofol have demonstrated a risk of over-sedation. We have incorporated a reaction-time monitor into the handset of the patient-maintained sedation system to add an individualised patient-feedback mechanism. This study assessed if such reaction-time feedback modification would reduce the risk of over-sedation in 20 healthy volunteers deliberately attempting to over-administer themselves propofol. All the volunteers successfully sedated themselves without reaching any unsafe endpoints. All volunteers maintained verbal contact throughout, in accordance with the definition of conscious sedation. The mean (SD) lowest S(p) O(2) was 97 (1.7) % when breathing room air and no volunteer required supplementary oxygen. The mean (SD) maximum effect-site propofol concentration reached was 1.7 (0.4) μg.ml(-1) . The present system was found to be safer than its predecessors, allowing conscious sedation, but preventing over-sedation.

Accidental radiation exposure leading to non-healing ulcers

Two patients with accidental radiation injury presented at the Sir Ganga Ram Hospital. The first patient, a 41-year-old male, presented with a large necrotic patch on his right gluteal region, which was debrided. Due to the progressive nature of the injury, he developed further necrosis and a non-healing ulcer over the right gluteal region, which was further debrided and covered with a tensor fascia lata flap. Further necrosis over the ischial region was debrided and covered with a pedicled gracilis muscle flap, following which he again required debridement and flap cover for the residual area, which then finally healed. The second patient had a history of radiation exposure followed by a non-healing ulcer on right arm. He was managed by debridement and flap coverage in a single sitting. These two cases suggest that wide excision, thorough debridement and coverage with vascularised tissue are effective in treating radiation ulcers and emphasise that all radiation sources and their management should be strictly controlled.

Comparison of glomerular filtration rate estimated by plasma clearance method with modification of diet in renal disease prediction equation and Gates method

Glomerular filtration rate (GFR) prediction equations are widely used in clinical practice for quick assessment of kidney function. Gates method using radionuclide technique is an alternative to prediction equations for quick assessment of GFR. Aim of the study was to compare Gates method and modification of diet in renal disease (MDRD) equation in a sizeable patient population with wide range of renal function to evaluate their clinical utility. GFR was estimated in 897 subjects with wide range of renal function by gates method, and MDRD equation and results were compared against measured GFR. Subjects were divided in to 4 groups (0-30 ml, 31-60 ml, 61-90 ml, >90 ml) on the basis of measured GFR and comparison between two methods done through linear regression analysis. Analysis of R² indicated that 56% of the interindividual variability for Gates GFR was in accordance to variation in measured GFR, in the GFR range of (0-30 ml), this value dropped to 39% in the GFR range of 31-60 ml, 40% in the GFR range of 61-90 ml, 26.4% in the GFR range of >90 ml, the corresponding figure for MDRD GFR were 47.9%, 31.1%, 17.6% and 16.1%, respectively. Gates method is more precise for GFR estimation at all levels of renal function.

Evaluation of intracranial space-occupying lesion with Tc99m-glucoheptonate brain single photon emission computed tomography in treatment-naïve patients

BACKGROUND

Glucoheptonate is a glucose analog with strong affinity for neoplastic brain tissues. Though extensively used as a tracer for detection of brain tumor recurrence, it's utility for characterization of intracranial lesions as neoplastic or otherwise has not been evaluated in treatment-naïve patients.

AIM

The study was conducted to determine if glucoheptonate has sufficient specificity for neoplastic lesions of brain so that it can be utilized as a single photon emission computed tomography (SPECT)-tracer for differentiating neoplastic intracranial lesions from non-neoplastic ones in treatment-naïve patients.

SETTINGS AND DESIGN

A cross-sectional analysis of treatment-naïve patients with intracranial space-occupying lesion done in a tertiary care hospital.

MATERIALS AND METHODS

Fifty-four consecutive patients with clinical and radiological features of space-occupying lesion were included in this study. Glucoheptonate brain SPECT was performed before any definitive therapeutic intervention. Histopathological verification of diagnosis was obtained in all cases.

STATISTICAL ANALYSIS USED

Descriptive statistics and student's 't' test.

RESULT

Increased glucoheptonate uptake over the site of radiological lesion was noted in 41 patients and no uptake was noticed in 13 patients. Histopathology of 12 out of the 13 glucoheptonate non-avid lesions turned out to be non-neoplastic lesion; however, one lesion was reported as a Grade-2 astrocytoma. Histology from all the glucoheptonate concentrating lesions was of mitotic pathology. The sensitivity, specificity and accuracy of glucoheptonate for neoplastic lesion was 97.6%, 100% and 98.1%.

CONCLUSIONS

Glucoheptonate has high degree of specificity for neoplastic tissues of brain and may be used as a tracer for SPECT study to differentiate neoplastic intracranial lesions from non-neoplastic ones.

Biodegradable-polymer-based, paclitaxel-eluting Infinnium stent: 9-Month clinical and angiographic follow-up results from the SIMPLE II prospective multi-centre registry study

BACKGROUND

SIMPLE II was a multi-centre, prospective registry study aimed at investigating the safety and efficacy of the Infinnium (Sahajanand Medical Technologies Pvt. Ltd, India) paclitaxel-eluting stent for the treatment of single de novo lesions in the native coronary arteries.

METHODS

One hundred and three patients with symptomatic coronary artery disease were treated for single de novo native coronary artery lesions using the Infinnium stent (paclitaxel concentration 1.4 mcg/mm2 released over 48 days) in a multi-centre, prospective study performed on 3 continents (Asia, Europe and South America). The primary safety endpoint was major adverse cardiac events at 30 days (MACE 30d) and efficacy was assessed by in-stent binary restenosis as measured by quantitative coronary angiography (QCA) at six-month follow-up. A clinical follow-up was scheduled at nine months.

RESULTS

The mean patient age was 58.5 years; 70.9% were males; 43.7% had unstable angina and 38.8% previous myocardial infarction. Risk factors included hypertension in 62.1%, hypercholesterolemia in 52.4%, current smoking in 32.0% and diabetes in 28.2%. Stent implantation was successful in all patients, with more than one stent being implanted in 9 patients (8.7%). Hierarchical MACE 30d was 2.9%. At nine months, 101 patients had clinical follow-up (1 patient had died and 1 refused). There was one death (1.0%), one Q-wave myocardial infarction (Q MI) (1.0%), three non-Q MIs (2.9%), one clinically-driven target lesion Coronary Artery Bypass Grafting (CABG) (1.0%), and one clinically-driven target lesion repeat percutaneous coronary intervention (re-PCI) (1.0%). The overall event-free rate at nine months was 93.2%. QCA revealed in-stent and in-segment late loss of 0.38+/-0.49 mm and 0.18+/-0.46 mm, resulting in binary restenosis rates of 7.3% and 8.3%, respectively. There was one case of late stent thrombosis in the patient experiencing the Q MI and subsequent re-PCI.

CONCLUSIONS

The Infinnium paclitaxel-eluting stent appears to be safe and efficacious for the treatment of single de novo lesions in coronary arteries in a patient population with symptomatic coronary artery disease (CAD).

Evaluation of a new effect-site controlled, patient-maintained sedation system in dental patients

We have designed a new effect-site controlled, patient-maintained sedation system for delivering propofol. In the previous systems we developed, the patients retained the use of the handset throughout the procedure and were able to increase the level of sedation. However, it was found that this could potentially lead to oversedation. In the present system, the patients were able to increase their level of sedation until a level was reached that was judged by the patients as being adequate to allow them to tolerate the injection of dental local anaesthetic. The handset was then taken from the patients and the effect site concentration of propofol was maintained at that level for the remainder of the procedure. To assess its safety and efficacy, the system was used to sedate 40 patients presenting for dental procedures under sedation. The system was used successfully and treatment was completed in 39 patients. The system was found to be safe. Both surgeon and patient approval scores were high. Although this study demonstrates the efficacy of effect-site controlled, patient-maintained propofol sedation in this group of patients, further work is required to confirm its safety.

Use of atropine in patients with recent myocardial infarction during exercise myocardial perfusion study

BACKGROUND

Patients with recent myocardial infarction frequently require a myocardial perfusion study for risk stratification. However a conclusive study cannot be accomplished in many due to non-attainment of target heart rate.

AIM OF THE STUDY

To evaluate the effect of pre-stress administration of atropine in exercise performance of patients with recent myocardial infarction.

MATERIAL AND METHODS

Study included 43 test and 43 control patients and were matched for their age, sex, status of pretest exercise tolerance, area of infarction and for interval between infarction and stress thallium test. Atropine (0.01 mg/kg) was administered intravenously 3 min prior to treadmill stress in all the 43 test patients and no atropine was administered to control patients.

RESULTS

Target heart rate was attained in 95.3% patients receiving atropine compared to in 67.4% of control patients. There was no significant difference between mean ages (p>0.33), basal BP (p>0.47), peak BP (p>0.18) of both groups. There was significant difference between the increment in exercise-induced heart rate (p<0.004), peak heart rate (p<0.001) and double product (p<0.001) attained between both groups. No significant adverse effect was noted in patients who received atropine.

CONCLUSION

Pre-stress administration of atropine in patients with recent myocardial infarction is safe and results in a significantly better exercise performance, which might be useful in decreasing the number of equivocal myocardial perfusion studies.

Do healthy potential kidney donors in india have an average glomerular filtration rate of 81.4 ml/min?

BACKGROUND

Until now, a normal reference range for glomerular filtration rate (GFR) in adult Indian potential kidney donors has not been determined and values from a western population are being used as reference.

AIM

To determine the reference range of GFR in healthy adult Indian potential kidney donors.

BASIC PROCEDURES

GFR was measured in 610 (250 male, 360 female, average age 35.16 years) healthy potential kidney donors using the 99mTc-DTPA (diethylenetriamine pentaacetic acid) two-plasma sample method of Russell.

RESULTS

The mean body surface area (BSA)-normalized GFR value of a young healthy Indian adult potential kidney donor was calculated as 81.4 +/- 19.4 ml/min/1.73 m2 BSA--for males it was 82.3 +/- 21.3 ml/min/1.73 m2 BSA and for females 80.8 +/- 18.1 ml/min/1.73 m2 BSA. There was no significant difference between derived mean GFR values in males and females with a p value of 0.37.

CONCLUSIONS

The normal GFR value for the healthy Indian adult potential kidney donor appears to be much lower than the accepted value for a western population. The mean GFR value of a young healthy Indian adult potential kidney donor is 81.4 +/- 19.4 ml/min/1.73 m2 BSA, which is significantly different from the normal value of 109-125 ml/min derived from a western population. These findings might be useful in deciding on a suitable kidney donor in an Indian context.

Postoperative residual tumour imaged by contrast-enhanced computed tomography and 201Tl single photon emission tomography: can they predict progression-free survival in high-grade gliomas?

AIMS

To evaluate if postoperative residual tumour imaged by either computed tomography or 201Tl single photon emission tomography (SPECT) carried out postoperatively could predict progression-free survival (PFS) in high-grade malignant gliomas.

MATERIALS AND METHODS

Thirty-three patients with high-grade malignant gliomas underwent both contrast-enhanced CT scan and 201Tl-SPECT postoperatively before receiving radiotherapy. The PFS was evaluated against the individual reports of the above two imaging studies by univariate analysis.

RESULTS

CT and 201Tl-SPECT were carried out within a median interval of 17 days after surgery. Of the 33 patients, CT and 201Tl-SPECT were reported as positive for residual tumours in 23 (69.7%) and 30 (91%) patients, respectively. Sensitivity, specificity and overall accuracy were 71.4%, 40% and 66.6% for CT, and 96.4%, 40% and 87.8% for 201Tl-SPECT, respectively, and were based on their last follow-up status (P = 0.627 for CT; P = 0.053 for 201Tl-SPECT). The median PFS for patients reported to be positive or negative on CT scan was 4 and 5 months, respectively (P = 0.202). With 201Tl-SPECT, although the median PFS for patients with a positive 201Tl uptake was also 4 months, it had not even reached for those reported having a negative 201Tl uptake (cumulative survival 66.7% at last follow-up) (P = 0.198). However, Karnofsky performance status (KPS) was the only significant predictor on univariate analysis (KPS: < 80 vs. > or = 80; P < 0.001) for PFS.

CONCLUSIONS

Although both the imaging modalities have a poor specificity, postoperative 201Tl-SPECT had a significantly better accuracy to predict the status at last follow-up than contrast-enhanced CT. Nevertheless, KPS remained the most significant outcome predictor for PFS in high-grade malignant gliomas.

A partially blinded randomised controlled trial of patient-maintained propofol sedation and operator controlled midazolam sedation in third molar extractions

Patient-maintained sedation using propofol has recently been shown to be effective for dental surgery. We compared this new technique to the established technique of operator administered midazolam. The two groups were compared before, during and after sedation. The two primary outcomes were time until discharge and oxygen saturation. Vital signs, anxiety and psychomotor skills were also compared. State anxiety was reduced to a greater extent in the propofol group (mean difference 10 (SD 4) mm; p = 0.010. Propofol patients recovered quicker (mean difference 7 (SD 1.4) min; p = 0.001). Propofol patients had a smaller reduction in arterial oxygen saturation (mean difference 0.8 (SD 0.3)%; p = 0.030), and a reduced increase in heart rate (mean difference 9 (SD 2) beats.min(-1); p < 0.001). Both techniques were well tolerated and safe. Propofol sedation offered superior anxiolysis, quicker recovery, less amnesia and less depression of simple psychomotor function.

Evaluation of bilioenteric anastomosis using quantitative hepatobiliary scintigraphy

BACKGROUND/AIMS

The patterns of quantitative hepatobiliary scintigraphy for bilioenteric anastomoses have not been objectively defined. This study was undertaken to establish the patterns of quantitative hepatobiliary scintigraphy in the patients with bilioenteric anastomoses performed for repair of postcholecystectomy benign biliary strictures.

METHODOLOGY

37 patients with bilioenteric anastomosis (Study group) and 10 postcholecystectomy healthy subjects (Controls) underwent quantitative hepatobiliary scintigraphy. Study group patients were further categorized into: Group A (n=27) - normal clinical and biochemical parameters, and Group B (n=10) - abnormal clinical and/or biochemical parameters. On scintigraphy, time of maximal activity and time of clearance of half of the activity was calculated at the liver parenchyma and hepatic hilum. Time of appearance of activity in the intestine was also recorded.

RESULTS

There was no significant difference in the scintigraphic parameters between Group A and Controls except for earlier appearance of activity in the intestines (p=0.036) in Group A. In Group B there was significant increase in the time of clearance of half of the activity at the liver parenchyma and hepatic hilum compared to Controls (p=0.003 and 0.036 respectively), and at the liver parenchyma compared to Group A (p=0.002).

CONCLUSIONS

Quantitative hepatobiliary scintigraphic patterns in patients with bilioenteric anastomosis were similar to those of postcholecystectomy controls. Patients with abnormal biochemical parameters had significant delay in clearance of activity. Significance of these scintigraphic patterns in this subset of patients can be determined only on long-term follow-up.

Clinical profile of hereditary spherocytosis in North India

AIMS OF THE STUDY

Hereditary spherocytosis (HS) is a familial hemolytic disorder manifesting as anaemia, recurrent jaundice, splenomegaly with marked heterogeneity in clinical presentation. The objective was to study the clinical spectrum of the disorder in India.

METHODOLOGY

We studied 50 HS patients and followed them for up to six years (Age range 2-47 years).

RESULTS

The presenting features were jaundice 35 out of 50, anaemia 30 out of 50 (requiring blood transfusion in 25). Splenomegaly was found in all patients. Increased osmotic fragility was found in all patients whereas spherocytes were found in only 19 out of 42 patients. Reduced red cell survival was noted in 9/12 patients studied with 51Cr labeled RBCs. There was a definite improvement in the hemoglobin values in those who underwent splenectomy. Thirteen cases had similarly affected family member/s. Fifteen of the cases had family history consistent with autosomal dominant (AD) inheritance (eight families) while in six cases (5 families), inheritance was likely to be autosomal recessive (AR). There was intrafamilial variability in the age of presentation in the AD families.

CONCLUSIONS

Our results suggest that both autosomal dominant and recessive patterns of HS are seen in India and the clinical profile of the Indian HS patients is similar to that described in other populations. HS presenting in childhood is also not uncommon. However, the predominant underlying protein defect in Indian patients needs to be characterized.

Classifying choledochal cysts using hepatobiliary scintigraphy

PURPOSE

This retrospective study was designed to classify choledochal cysts on the basis of the findings of hepatobiliary scintigraphy.

METHODS

Twenty-one patients with choledochal cysts (15 female, 6 male; mean age, 20 years) proved on the findings of endoscopic retrograde cholangiopancreatography (ERCP) or surgery and histopathologic analysis were included in the study. Two nuclear medicine physicians, blinded with regard to cholangiographic and operative details, were asked to review and to classify the type of choledochal cyst seen on the hepatobiliary scan. Later, scintigraphic results were compared with ERCP and surgical findings for a reference standard.

RESULTS

The findings of hepatobiliary scintigraphy correlated with ERCP and surgical findings in 18 of 21 cases (86%). Scintiscans correctly identified all type 1 cysts (12/12). The sensitivity of scintigraphy in diagnosing type 4 cysts was 66% (6 of 9 cases). It underestimated the intrahepatic extent of disease in type 4a biliary cysts (37%).

CONCLUSION

This study illustrates the utility of hepatobiliary scintigraphy in diagnosing type 1 and 4 choledochal cysts.

Aspirin renography in the diagnosis of renovascular hypertension: a comparative study with captopril renography

Captopril renography is used for the non-invasive diagnosis of renovascular hypertension, but suffers from the drawbacks of lower sensitivity and false-positive tests due to a fall in blood pressure. Aspirin renography has been proposed as a useful test for evaluation of unilateral renal artery stenoses of moderate degree. We studied the clinical usefulness of aspirin renography in 12 patients with a clinical suspicion of renovascular hypertension and compared it with captopril renography using 99Tcm-DTPA. The test was considered positive if there were changes in the time-activity curve according to the criteria specified by the American Society of Hypertension Working Group. Four patients with discordant results between captopril and aspirin underwent intra-arterial digital subtraction angiography. In two patients, the renal arteries were normal; captopril was false-positive in both these patients. Bilateral stenosis was noted in the third patient, with captopril being false-negative on the right side with moderate stenosis, whereas aspirin was true-positive. There was unilateral stenosis in the fourth patient; captopril was false-positive on the contralateral side. Our results suggest that aspirin renography is superior to captopril renography in the assessment of patients with a suspicion of both unilateral and bilateral renovascular hypertension.

Power Doppler imaging of acute renal transplant rejection

PURPOSE

We evaluated the usefulness of power Doppler imaging (PDI) in diagnosing acute renal-transplant rejection.

METHODS

Twenty-eight patients underwent 33 renal-transplant biopsies for suspected acute rejection. Patterns of renal parenchymal vascularity revealed by PDI in patients with abnormal biopsy results were compared with patterns in a group who had normal biopsy results. PDI examinations were reviewed retrospectively by 2 independent radiologists who had no knowledge of the biopsy results. A PDI diagnosis of acute rejection required marked vascular pruning in both the cortex and medulla. PDI results then were compared with transplant-biopsy results.

RESULTS

The sensitivity and specificity of PDI for diagnosing acute renal-transplant rejection were 40% and 100%, respectively. None of the patients with negative biopsy results had PDI abnormalities. The negative predictive value of PDI was 33%, and the positive predictive value was 100%.

CONCLUSIONS

In our study, an abnormal sonogram was highly predictive of acute transplant rejection. However, a normal sonogram did not exclude the possibility of rejection.

Assessment of vasoreactivity in brain edema by acetazolamide activation SPECT and PET

Our study was performed to find out cerebrovascular reactivity post acetazolamide administration in patients with peritumoral edema. Adult patients (n = 9) underwent CBF measurement by 99mTc-HMPAO SPECT pre and post 1 gram i.v. acetazolamide. In all patients, this procedure was repeated once again within 10 days of performing tumor removal. Five of these patients also underwent CBF measurement pre and post 1 gram i.v. acetazolamide post surgery only using oxygen-15 labeled H2O PET. Asymmetry index (AI) was calculated as ratio of ROI counts in the peritumoral edematous area and symmetrical ROI on the contralateral normal hemisphere. The AI increased after acetazolamide in edematous gray matter post operatively though the resting AI remained almost same post operatively. AI in edematous white matter showed non-significant increase post operatively both at rest and after acetazolamide. Good linear correlation of AI between PET and SPECT was observed both in gray and white matter. The improvement of vascular reactivity in edematous gray matter after tumor removal suggests that mass effect not only reduces CBF but also suppresses vascular reactivity. White matter vascular reactivity in early post operative period is little improved, possibly due to factors other than mass effect i.e. excess water accumulation in white matter perivascular space.

Comparison of vasodilatory effect of carbon dioxide inhalation and intravenous acetazolamide on brain vasculature using positron emission tomography

Carbon dioxide (CO2) and acetazolamide are increasingly being used as vasodilators to detect cerebrovascular reserve capacity in patients of chronic cerebrovascular disease. The functional cerebrovascular reserve or ability of cerebral vessels to lower their resistance in response to decrease in cerebral perfusion pressure is expressed as change in cerebral blood flow from baseline under a vasodilatory stimuli. Theoretically a vasodilator causing maximum vasodilation, and thereby expressing complete reserve capacity would be more suitable for such a purpose. We quantitatively compared the vasodilating effect of 5% CO2 inhalation and 1 g of intravenous acetazolamide by positron emission tomography. Cerebrovascular reserve was quantified in six patients with chronic cerebrovascular disease in the same sitting, using oxygen-15 labeled water (H2(15)O) positron emission tomography at rest, during 5% CO2 inhalation and after 1 g intravenous acetazolamide. A significant linear correlation in both nonlesion hemisphere (r = 0.701, p < 0.001) and in lesion hemisphere (r = 0.626, p < 0.005) was found between CO2 and acetazolamide for cerebrovascular reserve capacity. This correlation improved by considering cerebrovascular reserve per unit change in arterial carbon dioxide (r = 0.744, p < 0.001 in nonlesion hemisphere and r = 0.721, p < 0.001 in lesion hemisphere). The quantitative value of global reserve capacity was different by CO2 stimuli (5.2%) and acetazolamide (49.7%). Though a similar vasodilatory response is elicited by both vasodilators, acetazolamide seems to be more potent and therefore should be preferred to detect patients with exhausted cerebrovascular reserve capacity.

Fluorine-18 fluoro-2-deoxyglucose positron emission tomography in recurrent rectal cancer: relation to tumour size and cellularity

The aim of this study was to assess the value of fluorine-18 fluoro-2-deoxyglucose (FDG) positron emission tomography in patients with recurrent rectal cancer, in relation to tumour size and cellularity. Thirty-seven patients (21 mean and 16 women; mean age, 55.4+/-9.58 years) with suspected recurrence of rectal cancer were studied. FDG uptake was quantified by the differential absorption ratio (DAR). In 29 patients magnetic resonance imaging was also performed. To evaluate the signal intensity of the lesion, the lesion to muscle signal intensity ratios (SIR) were calculated on T2-weighted images. In seven patients who received surgical treatment the DAR and SIR were compared with the tumour cellularity. All 32 patients with confirmed recurrence showed increased FDG accumulation in the mass (DAR=4.57+/-1.89) in comparison with low FDG accumulation in five patients with scar (DAR=1.17+/-0.43). There was a significant correlation (r=0.661, P<0.001) between the DAR and the tumour diameter. There was no correlation between the DAR and SIR, whereas there was a significant correlation (r=0.565, P<0.01) between the DAR corrected using count recovery coefficient (DAR*) and SIR. In the histopathological findings there was a tendency for the DAR* and SIR to correlate with tumour cellularity. It is concluded that the DAR of recurrent rectal cancer should be evaluated taking into consideration the tumour size and cellularity.

Clinical evaluation of Tc-99m cystine. A new renal radiopharmaceutical

Tc-99m cystine has been proven to be a good renal agent in animals, but its clinical evaluation has not been reported. In this study, Tc-99m cystine was used for evaluation of renal function in normal subjects and patients with chronic renal failure as well as in renal transplant patients. The results are compared with similar studies that used Tc-99m DTPA and Tc-99m GHA. The clearance values also have been compared with I-131 OIH clearance. The results show that Tc-99m cystine has good radiopharmaceutical characteristics suitable for evaluation of both renal function as well as morphology.

Clinical evaluation of Tc-99m cystine. A new renal radiopharmaceutical

Tc-99m cystine has been proved to be a good renal agent in animals. Its clinical evaluation has not been reported. In this study, Tc-99m cystine is used for evaluation of renal function in normal subjects and patients with chronic renal failure as well as in renal transplant patients. The results are compared with similar studies using Tc-99m DTPA and Tc-99m GHA. The clearance values also are compared with I-131 OIH. The results show that Tc-99m cystine has good radiopharmaceutical characteristics suitable for evaluation of both renal function as well as morphology.

Interventional radiology in the management of superior thyroid artery injury which presents as a diagnostic dilemma

Following a forgotten iron splinter injury, a 19 year old male developed a slowly increasing extrathyroidal haematoma, which presented as a diagnostic dilemma. Surgical exploration failed to establish a diagnosis and was complicated by severe haemorrhage. Emergency angiography demonstrated injury to the superior thyroid artery. Therapeutic embolization and surgical exploration resulted in functional and anatomical recovery of the thyroid lobe.

99mTc-insulin: labeling, biodistribution and scintiimaging in animals

Porcine insulin was labeled with 99mTc by direct tin reduction. More than 95% labeling efficiency was obtained on paper chromatography in saline and methyl ethyl ketone. The stability of the labeled compound was confirmed by paper chromatography at 3 h post-labeling and by human serum albumin (HSA) challenge. PAGE pattern indicated no change in the electrophoretic behavior and the molecular size of insulin after the labeling procedure. Biodistribution in rats shows that kidney took up the maximum amount of 99mTc-insulin; maxima being maintained throughout 24 h post-injection. Liver and intestine were the other organs with significant uptake; the rest localizing little or negligible radioactivity. Most of the radioactivity was excreted via the renal pathway into urine. Scintiimages conformed to the biodistribution data. The results of this study present the potential of 99mTc-labeling of insulin by a simple method.

Skeletal scintigraphic findings in endemic skeletal fluorosis

Endemic skeletal fluorosis is characterized by bone, joint and muscle pain, progressive ankylosis of various joints and crippling deformities. Whole body skeletal scintigraphy with 99Tcm-methylene diphosphonate was performed for 17 symptomatic subjects suffering from this disorder. The fluoride content of drinking water ranged from 4.1 to 12.9 mg l-1 (normal < 1 mg l-1). Urinary and serum fluoride levels were markedly elevated. Serum calcium (total and ionized), inorganic phosphorus, creatinine and albumin were essentially normal while serum alkaline phosphatase was elevated in six subjects (mean +/- S.D. 206 +/- 106; range 22-1072 IU l-1). Skeletal radiology revealed a wide spectrum of bony abnormalities. Skeletal scintigraphy revealed a picture similar to metabolic 'superscan' in all subjects, i.e. increased tracer uptake in axial and appendicular skeleton, reduced soft tissue uptake, poor or absent renal images, prominent costochondral junction and 'tie' sign in sternum. Increased uptake was present in all subjects irrespective of age, water fluoride content, serum alkaline phosphatase level and radiological abnormalities. Our findings suggest the presence of a high bone turnover state in endemic skeletal fluorosis irrespective of other variables.

Intestinal lymphangiectasia: evaluation by CT and scintigraphy

Intestinal lymphangiectasia caused severe diarrhea and generalized edema in a 40-year-old man. The diagnosis was established by clinical, laboratory, and duodenal biopsy findings. The abnormalities detected on computed tomography (CT) and scintigraphy using 99mTc human serum albumin are herein described and pertinent literature is briefly reviewed.

Magnetic resonance imaging of the shoulder

Magnetic resonance imaging is an effective means for evaluating the painful shoulder. It has been shown to display accurately pathology associated with impingement syndrome and is useful in the detection of tears of the glenoid labrum. The role of magnetic resonance imaging in evaluation of synovial pathology has not yet been defined. Additional work is needed in this area.