Asia Oceania Journal of Nuclear Medicine & Biology
Volume:1 Issue: 2, Spring 2013

We sought to determine the usefulness of the 99mTc-MIBI (MIBI) washout rate for the evaluation of steroid therapy in cardiac sarcoidosis (CS). Eleven CS patients underwent MIBI myocardial SPECT both before and 6 months after initiating steroid therapy. The washout rate (WOR) of MIBI was calculated using early and delayed polar map images. The washout score (WOS) of MIBI was derived from the difference between the early and delayed total defect scores (TDS). Serum ACE and BNP exhibited significant improvement after the therapy (p = 0.004, p = 0.045). In the LV function, EDV and E/A ratio exhibited significant improvement after the therapy (p = 0.041, p = 0.007), while there were no significant differences between before and after therapy in EF or ESV. Early and delayed TDS showed no significant differences between before and after the therapy. In contrast, WOR differed significantly (p <. 0001), while WOS did not differ significantly between before and after the therapy. The washout rate of MIBI is suitable for assessment of cardiac function in CS with steroid therapy, being especially better than the washout score of MIBI for assessment of disease activity of mild myocardial damage in CS with steroid therapy.

Pre-clinical investigation of stem cells for repairing damaged myocardium predominantly used rodents, however large animals have cardiac circulation closely resembling the human heart. The aim of this study was to evaluate whether SPECT/CT myocardial perfusion imaging (MPI) could be used for assessing sheep myocardium following an acute myocardial infarction (MI) and response to intervention. 18 sheep enrolled in a pilot study to evaluate [99mTc]-sestamibi MPI at baseline, post-MI and after therapy. Modifications to the standard MPI protocols were developed. All data was reconstructed with OSEM using CT-derived attenuation and scatter correction. Standard analyses were performed and inter-observer agreement were measured using Kappa (). Power determined the sample sizes needed to show statistically significant changes due to intervention. Ten sheep completed the full protocol. Data processed were performed using pre-existing hardware and software used in human MPI scanning. No improvement in perfusion was seen in the control group, however improvements of 15% - 35% were seen after intra-myocardial stem cell administration. Inter-observer agreement was excellent (К=0.89). Using a target power of 0.9, 28 sheep were required to detect a 10-12% change in perfusion. Study demonstrates the suitability of large animal models for imaging with standard MPI protocols and it’s feasibility with a manageable number of animals. These protocols could be translated into humans to study the efficacy of stem cell therapy in heart regeneration and repair.

Multidrug resistance (MDR), which may be due to the over expression of P-glycoprotein (Pgp) and/or MRP, is a major problem in neoadjuvant chemotherapy of osteosarcoma. The aim of this study was to investigate the role of Tc-99m MIBI scan for predicting the response to pre-operative chemotherapy. Twenty-five patients (12 males and 13 females, aged between 8 and 52y) with osteosarcoma were studied. Before the chemotherapy, planar 99mTc-MIBI anterior and posterior images were obtained 10-min [tumor-to-background ratio: (T1/B1)10min] and 3-hr after tracer injection. After completion of chemotherapy, again 99mTc-MIBI scan was performed at 10-min after tracer injection. In addition to calculation of decay corrected tumor to background (T/B) ratios, using the 10-min and 3-hr images of the pre-chemotherapy scintigraphy, percent wash-out rate (WR%) of 99mTc-MIBI was calculated. Using the 10-min images of the pre- and post-chemotherapy scans, the percent reduction in uptake at the tumor site after treatment (Red%) was also calculated. Then after surgical resection, tumor response was assessed by percentage of necrosis. All patients showed significant 99mTc-MIBI uptake in early images. Only 9 patients showed good response to chemotherapy (necrosis≥90%) while 16 patients were considered as non-responder (necrosis<90%). There was no statistical significant difference between non-responders and responders in (T1/B1)10min.There was a significant negative correlation between WR% and percentage of necrosis (P=0.001). On the other hand, there was a significant correlation between Red% and percentage of necrosis (P<0.001).There was also statistical significant difference in WR% and Red% between non-responders and responders (both P< 0.001). Washout rate of 99mTc-MIBI in pre-chemotherapy scintigraphy as well as Red% using pre- and post-chemotherapy MIBI scintigraphy are useful methods for predicting response to neoadjuvant chemotherapy.

A novel IQ-SPECTTM method has become widely used in clinical studies. The present study compares the quality of myocardial perfusion images (MPI) acquired using the IQ-SPECTTM (IQ-mode),conventional (180° apart: C-mode) and L-mode (90° apart: L-mode) systems. We assessed spatial resolution, image reproducibility and quantifiability using various physical phantoms. SPECT images were acquired using a dual-headed gamma camera with C-mode, L-mode, and IQ-mode acquisition systems from line source, pai and cardiac phantoms containing solutions of 99mTc. The line source phantom was placed in the center of the orbit and at ± 4.0, ± 8.0, ± 12.0, ± 16.0 and ± 20.0 cm off center. We examined quantifiability using the pai phantom comprising six chambers containing 0.0, 0.016, 0.03, 0.045, 0.062, and 0.074 MBq/mLof 99m-Tc and cross-calibrating the SPECT counts. Image resolution and reproducibility were quantified as myocardial wall thickness (MWT) and %uptake using polar maps. The full width at half maximum (FWHM) of the IQ-mode in the center was increased by 11% as compared with C-mode, and FWHM in the periphery was increased 41% compared with FWHM at the center. Calibrated SPECT counts were essentially the same when quantified using IQ-and C-modes. IQ-SPECT images of MWT were significantly improved (P<0.001) over L-mode, and C-mode SPECT imaging with IQ-mode became increasingly inhomogeneous, both visually and quantitatively (C-mode vs. L-mode, ns; C-mode vs. IQ-mode, P<0.05). Myocardial perfusion images acquired by IQ-SPECT were comparable to those acquired by conventional and L-mode SPECT, but with significantly improved resolution and quality. Our results suggest that IQ-SPECT is the optimal technology for myocardial perfusion SPECT imaging.

To investigate the impact of respiratory motion on localization, and quantification lung lesions for the Gross Tumour Volume utilizing an in-house developed Auto3Dreg programme and dynamic NURBS-based cardiac-torso digitised phantom (NCAT). Respiratory motion may result in more than 30% underestimation of the SUV values of lung, liver and kidney tumour lesions. The motion correction technique adopted in this study was an image-based motion correction approach using, an in-house developed voxel-intensity-based and a multi-resolution multi-optimisation (MRMO) algorithm. All the generated frames were co-registered to a reference frame using a time efficient scheme. The NCAT phantom was used to generate CT attenuation maps and activity distribution volumes for the lung regions. Quantitative assessment including Region of Interest (ROI), image fidelity and image correlation techniques, as well as semi-quantitative line profile analysis and qualitatively overlaying non-motion and motion corrected image frames were performed. the largest transformation was observed in the Z-direction. The greatest translation was for the frame 3, end inspiration, and the smallest for the frame 5 which was closet frame to the reference frame at 67% expiration. Visual assessment of the lesion sizes, 20-60mm at 3 different locations, apex, mid and base of lung showed noticeable improvement for all the foci and their locations. The maximum improvements for the image fidelity were from 0.395 to 0.930 within the lesion volume of interest. The greatest improvement in activity concentration underestimation, post motion correction, was 7% below the true activity for the 20 mm lesion. The discrepancies in activity underestimation were reduced with increasing the lesion sizes. Overlay activity distribution on the attenuation map showed improved localization of the PET metabolic information to the anatomical CT images. The respiratory motion correction for the lung lesions has led to an improvement in the lesion size, localisation and activity quantification with a potential application in reducing the size of the PET GTV for radiotherapy treatment planning applications and hence improving the accuracy of the regime in treatment of the lung cancer.

Our previous study showed that a newly designed tracer radioiodinated 6-(3-morpholinopropoxy)-7-ethoxy-4-(3''-iodophenoxy)quinazoline ([125I]PYK) is promising for the evaluation of the epidermal growth factor receptor (EGFR) status and prediction of gefitinib treatment of non-small cell lung cancer. EGFR is over-expressed and mutated also in glioblastoma. In the present study, the expressions and mutation of EGFR were tested with [125I] PYK in glioblastoma in vitro and in vivo to determine whether this could be used to predict the sensitivity of glioblastoma to gefitinib treatment. Glioblastoma cell lines with different expression of EGFR were tested. Growth inhibition of cell lines by gefitinib was assessed by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) colorimetric assay. Uptake levels of [125I]PYK were evaluated in cell lines in vitro. Tumor targeting of [125I]PYK was examined by a biodistribution study and imaging by single photon emission computed tomography (SPECT). High concentrations of gefitinib were needed to suppress EGFR-mediated proliferation. The uptake of [125I] PYK in cell lines in vitro was low, and showed no correlation with EGFR expression or mutation status. Biodistribution study and SPECT imaging with [125I]PYK for xenografts showed no [125I]PYK uptake. The results showed prediction of gefitinib effectiveness was difficult in glioblastoma by [125I]PYK, which might be due to the complicated expression of EGFR status in glioblastoma. Thus, new tracers for sites downstream of the mutant EGFR should be investigated in further studies.

Duplication anomalies are quite common with ureteral duplication anomalies being the most frequent. Despite the relatively frequent incidence of a horseshoe kidney and duplication anomalies in any individual patient, the combination of horseshoe kidney and bilateral ureteric duplication is a very rare entity and very few cases have been reported to date. We present a case of a patient with novel combination of horse shoe kidney and congenital renal anomalies and their sequelae.

A male patient in his 20s presented at our clinic with pain caused by bone metastases of the primitive neuroectodermal tumor, and Sr-89 was administrated to palliate the pain. After receiving the injection, the patient complained of a slight burning pain at the catheterized area. Slight reddening and small circular swelling (diameter, 0.5 cm) were observed at the catheterized area. Sr-89 extravasation was suspected. To estimate the amount of subcutaneous Sr-89 leakage, bremsstrahlung imaging was immediately performed. We speculated that the skin-absorbed dose from the subcutaneous Sr-89 leakage was 1.78 Gy. The mildest clinical sign of local radiation injury was erythema. The received dose was higher than 3 Gy, and the time of onset was from 2 to 3 weeks. In our patient, local radiation injuries (LRIs) did not occur. Though requiring further verification, subsequent bremsstrahlung imaging and estimation of the skin-absorbed dose from the subcutaneous Sr-89 leakage are useful in confirming Sr-89 extravasation and in the decision making for the choice of treatment strategies for LRIs caused by Sr-89 extravasation.

Dr. Ajit Kumar Padhy MD, FAMS was a Senior Consultant, Department of Nuclear Medicine & PET at Singapore General Hospital, Singapore when he passed away on 22nd August 2013.Prior to this, he was Head of the Nuclear Medicine section International Atomic Energy Agency (IAEA), in Vienna for seven years. He was also Head of Nuclear Medicine at the All India Institute of Nuclear medicine, New Delhi, India His untimely demise left a wife and two loving sons, accomplished in their own rights. In the realm of Nuclear Medicine, the specialty he loved so much, he left a worldwide league of physicians and colleagues orphaned. His passion of the specialty will remain unsurpassed. His selfless devotion to uplift the practice of Nuclear Medicine in developing countries, encourage young doctors to do research and his peers to excel in this field was limitless. Born in Orissa, where he enjoyed his childhood, he will remain a treasure that belongs to the entire world. He loved life, and was even described by his classmates to be “enterprising and flamboyant”. He loved music, movies and dancing. He also loves to cook and his cooking was delicious. To us his colleagues, he was stylish and paid attention to small details when it comes to arranging meetings /conferences (being in the IAEA for 7 years and doing this around the world). He is so confident, kind and generous. He was honest and critical especially if it will be for your betterment and without intention to hurt.