Single-head Gamma Camera Research Articles

Normative Data of Liquid Gastric Emptying and Small-bowel Transit: A Prospective Cross-sectional Study.

The primary objective was to establish the reference values for liquid gastric emptying and small bowel. The secondary objectives encompassed comparing the anterior view and geometric mean methods, assessing gender differences, and exploring potential correlations with age. Thirty-five consecutive healthy participants (28 females and 7 males) with a mean age of 42 ± 11 years (median, 42; range, 23-65) underwent liquid gastric emptying scintigraphy at five intervals (0, 0.5, 1, 2, and 4 h), with optional additional imaging at 24 h. Liquid gastric emptying was evaluated using percent retention and half-time (T1/2). Small-bowel transit was assessed using the index of small-bowel transit (ISBT), calculated as the ratio of terminal ileal reservoir counts to total abdominal counts at 4 h. Reference values were established based on percentiles or mean and standard deviation (SD). Rapid small-bowel transit was determined through visual inspection. Statistical analysis involved paired Samples t-test or Wilcoxon signed-rank test for comparing imaging methods, independent Samples t-test or Mann-Whitney U-test for gender comparison, and Spearman's rank correlation for assessing age-related associations. A 2-tailed P < 0.05 indicated significance. Rapid liquid gastric emptying based on the geometric mean method was defined as percent retention <8% at 30 min, while delayed emptying as percent retention >33%, >20%, and >4% at 1, 2, and 4 h, respectively. The reference range of T1/2 of gastric emptying was 10-60 min. The reference value for small-bowel transit using the geometric mean method was established as ISBT >30% at 4 h, while rapid small-bowel transit was defined as the first visualization of activity in the cecum-ascending colon within 1 h. Parameters for liquid gastric emptying and small-bowel transit were notably higher in the anterior view method compared to the geometric mean method (P ≤ 0.019), except for percent retention at 2 h (P = 0.510). Nevertheless, the obtained reference values, whether based on percentiles or mean and SD, showed no notable variance between the two methods to warrant clinical significance. Gender did not display an impact on liquid gastric emptying or small-bowel transit in either method (P ≥ 0.173), and age demonstrated no significant moderate or strong correlations (Spearman's ρ ≤ 0.397). The study determined reference values for liquid gastric emptying and small-bowel transit through a standard gastric emptying scintigraphy protocol, avoiding additional complex procedures or extended imaging sessions. The established normative data can apply to individuals of both genders aged ≥18 years. While advocating the geometric mean method as the primary choice, the study acknowledges that in busy centers handling multiple studies with limited resources and a single-head gamma camera catering to multiple studies, the anterior view method remains a feasible alternative.

Use of intraoperative bone scintigraphy for resection of spinal osteoid osteoma.

The location and proximity to the spinal cord in spinal osteoid osteoma can increase the likelihood of an incomplete resection. Intraoperative bone scintigraphy (IOBS) can be used to verify location and complete surgical resection. To review our experience using IOBS for resection of intraspinal osteoid osteoma. IRB approved, retrospective review of IOBS-guided resection over 10years. Patients underwent injection of 200 uCi/kg (1-20mCi) 99mTc-MDP 3-4h prior surgery. Portable single-headed gamma camera equipped with a pinhole collimator (3- or 4-mm aperture) was used. Images were obtained pre-operatively, at the start of the procedure, and intraoperatively. Operative notes were reviewed. Evaluation of recurrence and clinical follow-up was performed. Twenty IOBS-guided resections were performed in 18 patients (median age 13.5years, 6-22years, 12 males). Size ranged 5-16mm, with 38.9% (7/18) cervical, 22.2% (4/18) thoracic, 22.2% (4/18) lumbar, and 16.7% (3/18) sacral. In all cases, IOBS was able to localize the lesion. After suspected total excision, IOBS altered the surgical plan in 75% of cases (15/20), showing residual activity prompting further resection. Median length of follow-up was 6months (range 1-156months) with 90% (18/20) showing complete resection without recurrence. Two patients had osteoid osteoma recurrence at 7 and 10months following the original resection, requiring re-intervention. IOBS is a useful tool for real-time localization and assessment of spinal osteoid osteoma resection. In all cases, IOBS was able to localize the lesion and changed surgical planning in 75% of cases. Ninety percent of patients achieved complete resection and remain recurrence free.

Performance Evaluation of the Nuclear Medicine Imaging Modalities at NINMAS

Performance evaluation of the imaging systems of nuclear medicine have been checked and compared with the previous data which were collected at the time of acceptance testing at the National Institute of Nuclear Medicine &amp; Allied Sciences (NINMAS). Performance measurements that have been carried out for the SPECT and SPECT-CT system recently were according to NEMA NU 2-2012 standard and IAEA Human Health Series No.1. Phantoms required for these tests to be performed were supplied by the vendors. Performance tests checked for the SPECT system were intrinsic flood field uniformity, intrinsic spatial resolution, center of rotation (COR), offset and alignment of axes, sensitivity and total performance test. The CT Phantom tests have been carried out for the visual inspection of resolution, contrast, noise and uniformity of the CT system. In these studies, performance evaluations of nuclear medicine imaging modalities including SYMBIA Evo Excel Dual Head SPECT Scanners, SYMBIA T16 SPECT-CT System and Nucline TH-45 Single Head Gamma Camera for Thyroid have been done to ensure the quality of service given to the patients. Performance measurements of these imaging modalities have shown satisfactory image quality. All data were compared with the acceptance testing data which were carried out during installation at the institute. Bangladesh J. Nuclear Med. 25(1): 28-35, 2022

Effective dose and radiation risk estimation in certain paediatric renal imaging procedures

Renal imaging (scintigraphy, intravenous urography (IVU) and computed tomography urography (CTU)) are non-invasive procedures that provide information essential in the diagnosis and treatment of renal disorders. The importance of these procedures notwithstanding, radiation exposure to the different tissues and organs could result in diverse reaction possibilities of varying severity. Accordingly, patient dose measurement of such exposures represent an essential step in seeking radiation dose optimization. Present study seeks to quantify effective doses for paediatric patients undergoing renal scintigraphy, IVU and CTU procedures using technetium-99m-diethylene-triamine-pentaacetic acid. Patients population consist of 116 patients (68 boys and 48 girls) were investigated using an Orbiter 37 single-head gamma camera, a digital imaging system and a dual-slice CT detector unit. Patient effective doses were estimated, administered activity ranging between 37.0 and 129.5 MBq per procedure. The mean effective dose and range (in mSv) for renal scintigraphy, CT Urography and IVU procedures were 1.0, 0.98 and 0.6 mSv per procedure respectively. The associated radiation risk estimates per procedure range between 80 and 130 cancers per one million procedures. Patients undergoing renal scintigraphy and CTU procedures received comparable doses such that if CT parameters are optimized this then allows the referring physician to consider the best diagnostic outcome regardless of modality selected.

In vivo quantification of renal function in mice using clinical gamma cameras

IntroductionIn preclinical research, the growing number of transgenic models has led to the need for renal-function studies in mice. Many efforts have been made to develop dedicated SPECT systems for rodents, but their availability is limited due to high capital costs. The aim of this work is to demonstrate the feasibility of mouse renal imaging by using an inexpensive alternative based on clinical gamma-cameras. MethodsA healthy mouse was scanned 3 h after injection of 6 mCi of Dimercaptosuccinic acid (DMSA) labeled with 99mTc by using a single-head gamma-camera in conjunction with a dedicated pinhole collimator. List-mode data were binned to emulate multiple injections of 1 mCi, 0.1 mCi and 0.01 mCi of 99mTc-DMSA and 6-min ventral and dorsal planar images were acquired and SPECT imaging (60 projection images acquired over 60 min) was performed. An optimization of the protocols in terms of injected activity, time scan, renal cortex uniformity and cortex-to-pelvis contrast was carried out. ResultsThe appropriate protocols were an injected activity of 0.6 mCi, combined with duration of scanning of 1 min for planar and 60 min for SPECT imaging. Our results were validated through the relative quantification of renal function, which showed that both kidneys contributed equally to the total function. They showed that functional structures of the mouse kidneys can be visually distinguished as easily as in human studies. ConclusionsOur findings showed the feasibility of conducting quantitative DMSA SPECT studies of anesthetized mice on clinical gamma cameras.

Preliminary Experience with Small Animal SPECT Imaging on Clinical Gamma Cameras

The traditional lack of techniques suitable for in vivo imaging has induced a great interest in molecular imaging for preclinical research. Nevertheless, its use spreads slowly due to the difficulties in justifying the high cost of the current dedicated preclinical scanners. An alternative for lowering the costs is to repurpose old clinical gamma cameras to be used for preclinical imaging. In this paper we assess the performance of a portable device, that is, working coupled to a single-head clinical gamma camera, and we present our preliminary experience in several small animal applications. Our findings, based on phantom experiments and animal studies, provided an image quality, in terms of contrast-noise trade-off, comparable to dedicated preclinical pinhole-based scanners. We feel that our portable device offers an opportunity for recycling the widespread availability of clinical gamma cameras in nuclear medicine departments to be used in small animal SPECT imaging and we hope that it can contribute to spreading the use of preclinical imaging within institutions on tight budgets.

Clinical Utility of Radiation Medicine 99mTc-Methylene Diphosphanate Bone Scintigraphy in the Early Diagnosis of Rheumatoid Arthritis.

The value of 99mTc-Methylene diphosphanate (99mTc-MDP) bone scan in predicting development of bony destruction, swelling, new bone erosions and skeletal deformities in small joints and bones was studied by visual evaluation of bone scans. 99m Tc-MDP was injected intravenously. 3 hours after the 99mTc-MDP injection, they have been underwent spot views of entire skeletons with planar scintigraphy in the anterior and posterior positions. All patients were examined under the Electronics Corporation of India Limited (ECIL) single head gamma camera imaging machine, equipped with a low-energy high-resolution parallel-hole collimator. In 9 patients with newly diagnosed rheumatoid arthritis a total of 60 patients of 99mTc-MDP bone scan were examined clinically, scintigraphically, and radiographically. The follow up period was 2 years. Seven patients found increased radiopharmaceutical increased in small joints. Onset of the rheumatoid disease was found in three out of seven patients. 2/9 patients, the joints which were eroded scintigraphically, was active at all the checkups. Erosions were detected earlier in foot joints than in finger joints. New erosions were especially prone to appear in joints with persisting and high scintigraphic activity. On the contrary, inactive joints by radionuclide scanning never eroded. Scintigraphic and clinical activity and radiographic erosion correlated significantly with each other. The sensitivity and specificity of visual scintigraphic assessment and the relative pixel activity method proved to be superior to the region of interest methods and clinical evaluation for prediction of bony erosions in patients of rheumatoid arthritis.

Abstract P1-01-20: Intra-operative sentinel node imaging with a portable gamma camera in breast cancer

Abstract Introduction: Access to nuclear medicine department and sentinel node imaging remain an issue in number of hospitals. Preoperative Scintigrams are performed to confirm uptake of radioactivity and localisation of nodes in centres where facilities are available. Sentinella® (Oncovision, Valencia, Spain) is a recently introduced portable imaging gamma camera used intraoperatively to produce real time visual localisation of SLNs. Sentinella® was tested in a controlled laboratory environment and we report the first use of this technique in breast cancer patients from UK. Methods: In the laboratory setting our aim was to compare the sensitivity and spatial resolution of the Sentinella® and a conventional gamma camera (cGC) used for sentinel node imaging by comparing it with the performance of a GE multi-purpose rectangular (MPR) conventional single head gamma camera normally used for sentinel node imaging. A simulator containing seeds 10kBq, 100kBq, 500kBq of radiocolloid Tc, mimicking SLN, were used. Seeds were placed at several depths in the axilla, at 3cm, 5cm and 8cm from the skin. Sentinella was placed first at 10cm and then 1cm away from the axilla and images were recorded at 1min and at 2.5min for every position. The cGC was placed 20 cm away from the simulator. Results: 68 Sentinella® images and 34 cGC images obtained from the simulated axilla. Sentinella® resolution is comparable with the cGC for objects close to the camera i.e. ∼ 5 cm, but reduces rapidly as it's moved away from the camera. For distances up to about 7 cm the Sentinella® with the blue collimator is more sensitive than the cGC. Sentinella detects high radioactivity (500 kBq) faster than cGC (1 vs 2.5min). In cases of low radioactivity (10kBq) Sentinella® was equally accurate and faster than cGC, when placed close to the skin. Identification of different number of beads with varying radioactivity was similar in Sentinella and cGC. Sentinella scans of the axilla were obtained in 85 patients undergoing SLNB. All patients had a preoperative lymphoscintigram. Serial Sentinella scans were obtained after removal of every hot node. Sentinella scans correlated with all the lymphoscintigrams in the 85 cases studied. Serial decay in activity was seen with removal of every hot node. Extra nodes were picked up in 6/85 cases after the axilla was found silent using hand held gamma probe. In 2/85 cases extra nodes found had cancer that led to axillary clearance. Sentinella scans were extremely useful in differentiating between a hot sentinel node and signal from injection site in upper outer quadrants of small sized breasts. Conclusion: Sentinella is accurate and fast in detecting radioactivity in the axilla. The anatomical shape of its collimator allows the operator to place it close to the axilla thus increasing sensitivity in cases of low radioactivity. Our independent tests and initial patient data confirm the excellent sensitivity and specificity. It's major advantage is that it can be used by surgeons to scan for residual nodes before completion of the procedure. It can resolve the problem of centres that do not have nuclear medicine departments. This portable gamma camera can definitely replace the use of conventional lymphoscintigrams saving time and money both for patients and the Hospital. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-01-20.

Predictors of bone metastasis in pre-treatment staging of asymptomatic treatment-naïve patients with prostate cancer

BackgroundThere is no general consensus on the optimal criteria for the application of bone scintigraphy in screening of bone metastasis in patients with prostate cancer. Our study was conducted to assess the value of bone scan for pre-treatment staging of asymptomatic treatment-naïve patients with prostate cancer. MethodsA total of 203 consecutive asymptomatic and treatment-naïve patients with prostate cancer (age: 67.6±6.4 years) who were referred to our department for whole body bone scintigraphy were enrolled in the study. Three hours after intravenous injection of 20mCi 99mTc-MDP, all patients underwent whole body bone scanning using a single head gamma camera. The planar images were supplemented with SPECT as needed for questionable abnormalities or those having uncertain location on planar images. ResultsThe mean serum PSA levels, serum alkaline phosphatase (ALP) and Gleason score (GS) were 42.41±37.1ng/ml, 223.9±129.9IU/L and 6.7±1.1, respectively. A total of 55 cases (27.1%) out of 203 patients had bone metastases.The univariate analysis showed that serum PSA levels, GS and ALP were all significant predictors of bone metastases. However, only serum PSA and ALP levels were found to be independent predictors of bone metastasis in the multivariate logistic regression analysis. The combination of PSA and ALP (in which patients with either elevated PSA [>20ng/ml] or elevated ALP were considered as positive) had the best screening value, with 98.2% sensitivity and 48.6% specificity. ConclusionSerum ALP screening can be employed as a tool to detect the subgroup of patients who are at high risk of bone metastases, while having a PSA of <20ng/ml. The combination of PSA and ALP can be used to improve predictability of bone metastasis in newly diagnosed patients with prostate cancer, without affecting staging accuracy.

Predictors of bone metastasis in pre-treatment staging of asymptomatic treatment-naïve patients with prostate cancer

There is no general consensus on the optimal criteria for the application of bone scintigraphy in screening of bone metastasis in patients with prostate cancer. Our study was conducted to assess the value of bone scan for pre-treatment staging of asymptomatic treatment-naïve patients with prostate cancer. A total of 203 consecutive asymptomatic and treatment-naïve patients with prostate cancer (age: 67.6±6.4 years) who were referred to our department for whole body bone scintigraphy were enrolled in the study. Three hours after intravenous injection of 20mCi (99m)Tc-MDP, all patients underwent whole body bone scanning using a single head gamma camera. The planar images were supplemented with SPECT as needed for questionable abnormalities or those having uncertain location on planar images. The mean serum PSA levels, serum alkaline phosphatase (ALP) and Gleason score (GS) were 42.41±37.1ng/ml, 223.9±129.9IU/L and 6.7±1.1, respectively. A total of 55 cases (27.1%) out of 203 patients had bone metastases. The univariate analysis showed that serum PSA levels, GS and ALP were all significant predictors of bone metastases. However, only serum PSA and ALP levels were found to be independent predictors of bone metastasis in the multivariate logistic regression analysis. The combination of PSA and ALP (in which patients with either elevated PSA [>20ng/ml] or elevated ALP were considered as positive) had the best screening value, with 98.2% sensitivity and 48.6% specificity. Serum ALP screening can be employed as a tool to detect the subgroup of patients who are at high risk of bone metastases, while having a PSA of <20ng/ml. The combination of PSA and ALP can be used to improve predictability of bone metastasis in newly diagnosed patients with prostate cancer, without affecting staging accuracy.

Determination of kidney function with 99mTc-DTPA renography using a dual-head camera

Single-head gamma camera renography has been used for decades to estimate kidney function. An estimate of the glomerular filtration rate (GFR) can be obtained using Tc-diethylenetriaminepentaacetic acid (Tc-DTPA). However, because of differing attenuation, an error is introduced when the kidney depth or kidney size is unequal. This error can be reduced using geometric mean data obtained from dual-head renography. The aim of this study was to compare single-head versus dual-head assessment of single kidney function. Thirty-four patients were examined with (a) single-head renography, acquiring counts from the left ventricle and kidneys from a posterior projection, and simultaneously with (b) dual-head renography, acquiring counts from the left ventricle from an anterior projection and kidneys from both anterior and posterior projections using geometric mean values. Single kidney GFR from both models was estimated (GFRcam1 and GFRcam2, respectively) and compared with GFR determined with plasma samples of Tc-DTPA (GFRps). The prediction intervals of GFRcam1 and GFRcam2 compared with GFRps did not differ significantly (SD of GFRcam1-GFRps=17.6 ml/min and SD of GFR2-GFRps=15.5 ml/min; P=0.48). The corresponding coefficients of variation were 16.5 and 14.7%, respectively. There is no difference in variance between GFR estimated from single-head renography and that estimated using dual-head renography. Hence, dual-head camera renography might be useful in daily practice with the potential to provide a better estimate of absolute function in each kidney and the relative kidney function in patients with differing kidney depths and/or malformed kidneys.

Standardization of Techniques for Using Planar (2D) Imaging for Aerosol Deposition Assessment of Orally Inhaled Products

Two-dimensional (2D or planar) imaging with (99m)Tc radiolabels enables quantification of whole-lung and regional lung depositions for orally inhaled drug products. This article recommends standardized methodology for 2D imaging studies. Simultaneous anterior and posterior imaging with a dual-headed gamma camera is preferred, but imaging with a single-headed gamma camera is also acceptable. Correction of raw data for the effects of gamma ray attenuation is considered essential for accurate quantification, for instance, using transmission scanning with a flood-field source of (99m)Tc or (57)Co. Evidence should be provided of the accuracy of the quantification method, for instance, by determining "mass balance." Lung deposition may be expressed as a percentage of ex-valve or ex-device dose, but should also be given as mass of drug when possible. Assessment of regional lung deposition requires delineation of the lung borders, using X-ray computed tomography, radioactive gas scans ((133)Xe or (81m)Kr), or transmission scans. When quantifying regional lung deposition, the lung should be divided into outer (O) and inner (I) zones. A penetration index should be calculated, as the O/I ratio for aerosol, normalized to that for a radioactive gas or transmission scan. A variety of methods can be used to assess lung deposition and distribution. Methodology and results should be documented in detail, so that data from different centers may be compared. The use of appropriate methodology will provide greater confidence in the results of 2D imaging studies, and should allay concerns that such studies are qualitative or semiquantitative in nature.

Evaluation of Regional Brain Perfusion in Patients with Pseudoexfoliation Syndrome

Pseudoexfoliation syndrome (PES) is characterised by the accumulation of abnormal extracellular fibrillar material in ocular tissue, which develops with ageing, and can lead to ocular complications, including glaucoma, cataract, zonular damage, and keratopathy. It has been shown that extraocular accumulation of pseudoexfoliation matter can occur in tissues such as the heart, lung, liver, kidney, cerebral meninges, aorta, and adventitia layer of cerebral arteries. Acute vascular complications are seen commonly with the involvement of the systemic vasculature. Pseudoexfoliation syndrome has also been reported in dementia and stroke patients. In this study, the authors aimed to evaluate regional brain perfusion in pseudoexfoliation syndrome patients. Twenty-four patients with PES with glaucoma (14 female, 10 male) and a control group of 19 healthy volunteers (10 female, 9 male) were included in the study. There was no cerebrovascular or psychiatric complaint in the patient or control group, and all subjects were right-handed. Brain perfusion single-photon emission computed tomography (SPECT) images were taken by low-energy general purpose collimator of a single-headed gamma camera after intravenous injection of 25 mCi technetium-99m-hexamethylpropylene amine oxime (Tc99m-HMPAO). To obtain the corticocerebellar ratio by semiquantitative analysis, 3 × 3 pixel regions of interest were drawn on transaxial sections, and the counts of frontal, temporal, parietal, and occipital regions were divided by the counts of the cerebellar region bilaterally. The mean ages of the PES and control groups were 67.83 ± 9.03 and 64.52 ± 6.88 years, respectively. The mean corticocerebellar ratio in PES was decreased in frontal, temporal, parietal, and occipital lobes bilaterally (p value interval min: 0.001, max: 0.049). The results showed that there was a decrease in frontal, temporal, parietal, and occipital cortices perfusion in PES patients bilaterally.

Exprerimental Evaluation of a Dedicated Pinhole SPECT System for Small Animal Imaging and Scintimammography

Nuclear medicine (SPECT and PET) provides functional information, which is complementary to the structural. In cancer imaging radiopharmaceuticals allow visualization of cancer cells functionality, thus small cell population can be imaged. This allows early diagnosis, as well as fast assessment of response to therapy. Our system is a single head gamma camera based on an R3292 position sensitive photomultiplier tube (PSPMT), coupled to a 10cm in diameter CsI:Tl crystal. We have assessed two CsI:Tl crystals with pixel size of 2x2mm2 and 3x3mm2 respectively. Three collimators were tested: a) a hexagonal, 1.1mm in diameter, general purpose parallel hole collimator b) a 1mm pinhole and c) a 2mm pinhole. Systems were tested using capillary phantoms. All measurements were carried out in photon counting mode with gamma radiation produced by 99mTc. Using the 2x2mm2 crystal and the 1mm pinhole collimator - a resolution better than 1mm was achieved. This allows very detailed imaging of small animals. Using the 3x3mm2 and the 2mm pinhole collimator a resolution of 1.3mm was possible with suitable sensitivity for breast imaging. Those results indicate that this system is suitable for animal and breast studies. The next step will be clinical evaluation of the camera.

Exprerimental Evaluation of a Dedicated Pinhole SPECT System for Small Animal Imaging and Scintimammography

Nuclear medicine (SPECT and PET) provides functional information, which is complementary to the structural. In cancer imaging radiopharmaceuticals allow visualization of cancer cells functionality, thus small cell population can be imaged. This allows early diagnosis, as well as fast assessment of response to therapy. Our system is a single head gamma camera based on an R3292 position sensitive photomultiplier tube (PSPMT), coupled to a 10cm in diameter CsI:Tl crystal. We have assessed two CsI:Tl crystals with pixel size of 2x2mm 2 and 3x3mm 2 respectively. Three collimators were tested: a) a hexagonal, 1.1mm in diameter, general purpose parallel hole collimator b) a 1mm pinhole and c) a 2mm pinhole. Systems were tested using capillary phantoms. All measurements were carried out in photon counting mode with gamma radiation produced by 99m Tc. Using the 2x2mm 2 crystal and the 1mm pinhole collimator - a resolution better than 1mm was achieved. This allows very detailed imaging of small animals. Using the 3x3mm 2 and the 2mm pinhole collimator a resolution of 1.3mm was possible with suitable sensitivity for breast imaging. Those results indicate that this system is suitable for animal and breast studies. The next step will be clinical evaluation of the camera.

Abstract P1-01-25: Sentinella® an Alternative for Conventional Scintigram and a Modality To Improve Intra-Operative Localisation of Sentinel Nodes in Breast Cancer

Abstract Sentinel Lymph Node (SLN) biopsy is now a standard practice for staging of the axilla in early breast cancer. Access to nuclear medicine department and sentinel node imaging reamins an issue in number of hospitals in the UK and many parts of the word Sentinella® is a new portable imaging camera used intraoperatively to produce real time visual localisation of Sentinel nodes. Sentinella® was tested in a controlled laboratory environment at our centre and we report the first use of this novel technique in Breast cancer patients from UK. Methods: Sensitvity and spatial resolution of Sentinella® mobile gamma camera was compared with a CGC (conventional single headed gamma camera) normally used for sentinel node imaging. Spatial resolution was measured by calculating the full width half maximum (FWHM) of a line profile measured perpendicular to the image of a capillary tube filled with high activity concentration technetium-99m pertechnetate. Next a special simulator mimicking the axilla was planted with seeds containing radiocolloid Tc, mimicking lymph nodes. Seeds were placed at varying depths in the axilla. For each combination of depths and radioactivity images with Sentinella® and CGC were obtained. Sentinella® scans of the axilla was also obtained in 50 patients undergoing SLNB to correlate with the preoperative scintigrams and determine presence of any residual hot nodes after use of the standard hand held gamma probe.If hot areas suggesting residual lymph nodes were detected, further exploration was carried out until no further residual activity was noted. Results Sentinella® resolution is comparable with the CGC for objects close to the camera i.e. ∼ 5 cm, but reduces rapidly as you move away from the camera. For distances up to about 7 cm the Sentinella® with the blue collimator is more sensitive than the CGC. 68 Sentinella® images and 34 CGC images obtained from the simulated axilla. Sentinella detects high radioactivity (500 kBq) faster than CGC (1 vs 2.5min). In cases of low radioactivity (10kBq) Sentinella® was equally accurate and faster than cGC, when placed close to the skin. Identification of different number of beads with varying radioactivity was similar in Sentinella and CGC. Sentinella® scans correlated with all the lymphoscintigrams in demonstrating hot lymph nodes in all the 50 cases. Sentinella® scans demonstrated a serial decay in activity with removal of every hot node and its LED guided localisation helped in detecting residual nodes. Sentinella® picked up extra nodes in 5/50 cases (10%) after the axilla was found silent using hand held gamma probe.In 2/50 (4%) cases extra nodes found using Sentinella® had presence of cancer that led to a complete Axillary clearance Conclusion: The initial patient and laboratory data confirms the excellent sensitivity and specificity of the machine in localisation of radioactive nodes. This new imaging technique will increase our pick up of sentinel lymph nodes intraoperatively that are missed due to inadequate visualisation and provide an alternative to static scintigram imaging. This would be particularly useful in centres that do not have nuclear medicine facilities on site. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-01-25.

Effects of terlipressin and somatostatin on liver and thorax blood volumes in patients with cirrhosis

Variceal bleeding in cirrhosis can cause liver ischaemia and deteriorate the hyperdynamic state; thus, the effects of vasoconstrictor therapy on liver blood volume (LBV) and thorax blood volume (ThBV) are important. To evaluate and compare the effects of terlipressin and somatostatin on LBV and ThBV in stable patients with cirrhosis and portal hypertension. Twenty patients were studied (Child-Pugh class A/B/C: 5/8/7). The radioactivities in the liver region (LRR) and the thorax region (ThRR) by single-head gamma camera technique, as indicators of LBV and ThBV, respectively, and systemic haemodynamics were measured at baseline and after intravenous infusion of 2 mg of terlipressin (n=10) or somatostatin 250 mg/h after an initial bolus of 250 mg (n=10). LRR and ThRR decreased significantly with increasing severity of cirrhosis. Thirty minutes after terlipressin infusion, LRR and ThRR increased by 7.8 ± 4.4% (NS) and 14 ± 5.3% (P=0.01) compared with baseline values; the increase in ThRR was significantly related to the increase in LRR (r=0.682, P=0.03). In contrast, somatostatin reduced LRR and ThRR by 13.3 ± 6.5% (P=0.07) and 1 ± 4% (NS) respectively. LRR and ThRR increased significantly in the terlipressin group compared with the somatostatin group (P=0.01 and P=0.02 respectively). Terlipressin reduced cardiac output and heart rate (both P=0.01) and increased the mean arterial pressure (MAP) and systemic vascular resistance (P=0.009 and P=0.002 respectively); MAP decreased after somatostatin infusion (P=0.03). Terlipressin, but not somatostatin, maintains LBV, increases ThBV and improves the hyperdynamic state in cirrhosis. These effects can be beneficial in variceal bleeding, particularly in patients with advanced liver disease.

Parameters Affecting on Intrinsic Uniformity Test For MEDISO

The most basic and sensitive routine quality control (QC) of gamma camera is that of intrinsic uniformity. Intrinsic uniformity must be assessed daily and after each repair, it must be critically evaluated and any necessary action must be undertaken before using the gamma camera for patient imaging. The main objective of this work is to determine the best parameters for daily quality control testing of intrinsic uniformity for the single-head gamma camera from MEDISO Company installed at Institute of Nuclear Medicine University of Gezira. Intrinsic uniformity test was done by placing a point source TcO (Tc) in front of the detector with removed collimator to measure the effect of correction matrix, source-to-camera distance, a count rate and activity volume on intrinsic uniformity.The result shows that the best intrinsic uniformity image obtained at distance of 100 cm, with correction matrix, activity volume in range of 0.1 0.4 ml in 3 ml syringe and a count rate in between 25 30 kcps which takes less than 14 min to get uniform image.

Nuclear Imaging of the Liver: Is There a Diagnostic Role of HIDA in Posttransplantation?

Background and Aims Biliary complications are common after liver transplantation. This study sought to assess the value of hepatic iminodiacetic acid (HIDA) scans (hepatobiliary iminodiacetic acid scan) to detect early posttransplantation biliary complications. Methods From April 2003 to June 2006, 34 liver transplantations (recipients of mean ± SD age of 43.0 ± 15.7 years) were performed in 25 (73.5%) males from 20 (58.8%) cadaveric donors and 14 (41.2%) living-related donors. The subjects underwent HIDA scans using a single head gamma camera Meridian (Philips) after intravenous (IV) administration of 185 MBq Tc-99m Disofenin. The mean time ± SD posttransplantation to HIDA scan was 14.6 ± 18.2 days (range, 0–74). The results were compared with endoscopic retrograde cholangio pancreatography, magnetic resonant cholangiopancreatography, percutaneous cholangiograhy, and/or liver biopsy. Results Twenty-four abnormalities were detected by HIDA scan in 16 patients (47.1%): 10 (29.4%) biliary leaks; 4 (11.4%) biliary obstruction or cholestasis; 1 (2.9%) delayed uptake; 5 (14.7%) delayed blood pool clearance; and 8 (23.5%) delayed transit to the bowel. The complications were more common among living-donor compared with deceased-donor graft recipients, albeit a not statistically significant difference ( P = .066). Total and direct bilirubin levels were significantly higher in patients with abnormal than normal HIDA scans ( P = .011 and P = .040, respectively). The sensitivity and specificity of HIDA scans to detect overall postoperative complications were 100% and 66.7%, respectively. Biliary leak results were false positives in 7/10 patients, and true in 3. Detection of obstruction was 75% sensitive by HIDA. Conclusion HIDA scans are a noninvasive, reliable modality for early exclusion of posttransplantation biliary complications. However, correlation with clinical status and imaging modalities is essential to confirm detected abnormalities.

The effect of filtrating and reconstruction method on the left ventricular ejection fraction derived from GSPET: a statistical comparison of angiography and echocardiography

There are different protocols of reconstruction in myocardial gated imaging that produce different values of left ventricular ejection fraction (EF). We attempted to determine how the parameters of reconstruction affect the calculated EF. The results were statistically compared with the values obtained from angiography and echocardiography. In this retrospective study, the data from 23 patients were used. All the patients had the angiographic and the echocardiographic data within 2 weeks before the test. Imaging was performed using a single-head gamma camera using technetium-99 methoxyisobutylisonitrile. The image data were reconstructed using 50 different combinations of the ramp, Hanning, Butterworth, Wiener, and Metz filters. The ordered subset expectation maximization (OSEM) technique was also examined using 12 combinations of iteration and subset. The calculated EF values were analyzed and compared with the echocardiographic and angiographic results. The backprojection technique produced higher values of EF than those derived from echocardiography and angiography. The OSEM on the other hand produced lower values when compared with echocardiography and angiography. On using the backprojection technique, the maximum correlation between the values derived from gated single-photon emission tomography and echocardiography (r=0.88, P<0.01) and angiography (r=0.81, P<0.01) was observed when using the Metz filter (full width at half maximum=5 mm and order=9) and the Gaussian filter (alpha=3), respectively. In the case of the OSEM technique, the maximum correlation with both angiography and echocardiography was observed when using the iteration=2 and the subset=12. On the average, the backprojection technique produces higher values, and iteration technique produces lower estimation of the EF when compared with angiography and echocardiography.