Whole-Body Bone Scan Image Enhancement Algorithms

In this study, the optimal input parameters point spread function (PSF) and the number of iterations of the Richardson-Lucy algorithm were experimentally determined to restore Tc-99 m methyl diphosphonate (MDP) whole-body bone scan images. The experiment was performed on 60 anonymized Tc-99 m MDP whole-body bone scan images. Ten images were used for estimating the optimum value of PSF and the number of iterations to restore scintigraphic images. The remaining 50 images were used for validation of estimated parameters. The image quality of observed and restored images was assessed objectively using blind/referenceless image spatial quality evaluator (BRISQUE), mean brightness (MB), discrete entropy (DE), and edge-based contrast measure (EBCM) image quality metrics. Image quality was subjectively assessed by two nuclear medicine physicians (NMPs) by comparing the restored image quality with observed image quality and assigning a score to each image on the scale of 0-5. Based on BRISQUE, MB, DE, and EBCM scores, the restored images were significantly sharper, less bright, had more detailed information, and had less contrast around edges compared to the input images. The restored images had improved resolution based on visual assessment as well; NMPs assigned an average image quality score of 4.00 to restored images. Maximum resolution enhancement was noticed at PSF (size: 11 pixels, sigma: 1.75 pixels) and the number of iterations = 10. With the increase in the number of iterations, noise also gets amplified along with resolution enhancement and affects the detectability of small lesions; in the case of relatively low noisy input images, the number of iterations = 5 gave better results. Tc-99 m MDP bone scan images were restored to improve image quality using the Richardson-Lucy algorithm. The optimum value of the PSF parameter was found to be of size = 11 pixels and sigma = 1.75 pixels.

Today's, the image processing applications are obvious in the various sciences. The medical image processing has achieved to acceptable results in the field of diagnosing disease. One of these applications which is discussed in this paper is diagnosis injury in whole body bone scan. Whole body bone scan has some applications in the diagnosis of benign lesions such as cardiovascular disease and metabolic bone and sports injuries and also to investigate the pervasiveness of bone. One of the main criteria to diagnose complications in the body is area with high brightness ‎to the brightness of adjacent areas in the image or asymmetry of the brightness in the two-sided areas of the body. In this study, a software has been implemented about the detection of disease-suspected areas that strategies to increase the pixel intensity have been considered to make easier the image segmentation and innovative methods of researcher have been implemented in image preparation to convert to binary mode and find suspected areas. In addition, the software automatically creates reports, this feature will be a big contribution to the doctor. Software assessment has been done on 11 whole body bone scan images and provided the results to the physician, the software succeeded to find the 41 correct areas from 44 injured areas, 93.18% of cases have been successfully identified. In terms of the number of errors in the areas of diagnosis, 30 cases were observed in 11 images which shows an average of 2.72 errors on each image.

The purpose of this study is to assess working environment preferences of radiological technologists using conjoint analysis. We carried a questionnaire survey on working environment preferences for 200 radiological technologists working in medical facilities in Japan. We defined eight characteristics for virtual medical facilities as follows: presence of colleagues who can be consulted, employment status, number of overtime work per month, academic meeting participation, number of hospital beds, presence of nuclear medicine imaging systems and radiation therapy systems, location of medical facilities, and change rate in annual income. A total of 18 virtual medical facilities were selected by an orthogonal array table using above-mentioned characteristics. The acquired data by the pairwise comparison method were analyzed by conjoint analysis. Marginal rates of substitution between income and non-pecuniary characteristics, which represent radiological technologists' preferences, were also calculated. The factors influenced on their preferences were the following: employment status is not part-time, medical facility is smaller in scale, nuclear medicine imaging systems and radiation therapy systems are set up, and the number of overtime work is less. It was suggested that radiological technologists have a tendency to avoid increase of workloads and select his/her working place with emphasis on own experiences.

The digital cadmium-zinc-telluride (CZT)-based SPECT system offers good energy resolution. However, the impacts of dual-energy window scatter correction on image quality under narrower primary energy windows remain to be determined. This study aimed to assess the impacts of SC (with scatter correction) and NOSC (without scatter correction) on image quality under different primary energy windows. We used a standard NEMA/IEC 2007 phantom containing six hollow spheres of various sizes to simulate the human body at four target-to-background ratios (T/B ratio, the ratio of the average radioactive activity concentration in the target region to that in the background region, 32:1, 16:1, 8:1, and 4:1, respectively), by filling with 99mTcO4-. For clinical validation, we recruited 20 patients and analyzed their whole-body bone scan images. Phantom and patient images were acquired with the Discovery NM/CT 670 CZT with list mode. Image quality of phantom was measured by calculating indicators from the NEMA NU 2-2018 standard, including percent background variability and percent contrast. Image quality of patients was measured by calculating coefficient of variation (COV), contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR). Visual quality was evaluated by two experts. Higher percent background variability and COV values were present when SC was applied regardless of which energy window, acquisition time, or T/B ratio used, and statistically significant differences were observed between all SC and NOSC groups for both phantoms and patients. For phantoms, percent contrast values of most SC groups were higher than those of NOSC groups. For patients, CNRs and SNRs of SC groups were higher than those of NOSC groups (all P < 0.05). Visually, SC had higher visual scores than NOSC for both phantoms and patients. SC significantly improves image contrast while minimizing concomitant image noise to a great extent and provides good visual image quality across different primary energy windows overall.

Quantitative studies of bone using (99m)Tc-methylene diphosphonate ((99m)Tc-MDP) have a potentially valuable role in investigating the treatment of patients with metabolic bone disease. In this study we compared 3 different methods of measuring whole-skeleton (99m)Tc-MDP plasma clearance (K(bone)) in 12 osteoporotic postmenopausal women (mean age, 67.3 y) before participation in a clinical trial of an osteoporosis therapy. The aim was to compare the consistency and accuracy of the 3 methods before their use in evaluating the subjects' response to treatment. Subjects were injected with 600 MBq (99m)Tc-MDP and 3 MBq (51)Cr-ethylenediaminetetraacetic acid ((51)Cr-EDTA) and whole-body bone scan images were acquired at 10 min, 1, 2, 3, and 4 h. Two-minute static images of the thighs were acquired immediately after the 1- to 4-h whole-body scans. Six blood samples were taken between 5 min and 4 h, and free (99m)Tc-MDP was measured using ultrafiltration. The glomerular filtration rate (GFR) was estimated from the (51)Cr-EDTA plasma curve. The methods used to evaluate K(bone) were (a) the area-under-the-curve (AUC) method, in which the GFR measurement was subtracted from the total (bone plus renal) clearance (K(total)) measured from the free (99m)Tc-MDP plasma curve; (b) the modified Brenner method, in which (99m)Tc-MDP renal clearance estimated from the whole-body counts was subtracted from the total clearance measured from the rate of elimination of tracer from soft tissue; and (c) the Patlak plot method, which was also used to derive regional values of K(bone) for the skull, spine, pelvis, arms, and legs. There was good agreement between the 3 methods of measuring K(bone). (mean K(bone) +/- SD: AUC method, 30.3 +/- 6.4 mL x min(-1); Brenner method, 31.1 +/- 5.8 mL x min(-1); Patlak method, 35.7 +/- 5.8 mL x min(-1)). The correlation coefficients between the methods varied from r = 0.767 (P = 0.004) to r = 0.805 (P = 0.002). Regional measurements of (99m)Tc-MDP clearance gave the following percentages of the whole-skeleton clearance: skull, 13.3%; spine, 16.6%; pelvis, 17.2%; arms, 11.1%; legs, 23.7%. The 3 methods gave consistent and accurate measurements of K(bone). The Patlak method can be used to study regional as well as total-skeleton values of K(bone).

Towards efficient Monte Carlo N-Particle simulation of a positron emission tomography (PET) via source volume definition

We have developed a computerized scheme for a temporal subtraction (TS) image in successive whole-body bone scans and demonstrated the clinical utility of this scheme in the prospective clinical study. Recently, bone scan index (BSI) has been used for the quantitative analysis of bone metastases. The calculation of BSI requires anatomical segmentations for applying the weight fraction. In this study, in order to evaluate a change of BSIs in successive whole-body bone scans, an anatomical segmentation scheme was incorporated into the temporal subtraction image. Total of 300 cases of successive bone scans in which each case includes a pair of two images for anterior and posterior whole body views, were corrected retrospectively with the following inclusion criteria; 1) at least one abnormal finding in either view, and 2) a maximum number of 20 interval changes. We used 100 cases for training computerized scheme and the remains for the independent test. For the computerized scheme of an anatomical segmentation, one normal case (the standard case) was initially selected to create a standardized image in each view. Each of the standardized images for anterior and posterior views was produced by averaging all training images in which the size, orientation, and location of a skeletal region in a bone scan image were adjusted to those of the standard case by using a linear interpolation. Templates of seven anatomical regions, such as skull, ribs, thoracic vertebrae, lumber vertebrae, pelvis, upper arms, and femurs, were determined manually on the standardized image. A number of parameters for adjusting a current image to the standard image were applied to the templates of anatomical regions to fit those regions into the previous, current and TS image. Preliminary result obtained from 143 test cases (286 TS images) indicated that 99.3% (284/286) of temporal subtraction images were correctly segmented anatomically by use of this proposed method..

Whole-body bone scan is one of the most frequent diagnostic procedures in nuclear medicine. Especially, it plays a significant role in important procedures such as the diagnosis of osseous metastasis and evaluation of osseous tumor response to chemotherapy and radiation therapy. It can also be used to monitor the possibility of any recurrence of the tumor. However, it is a very time-consuming effort for radiologists to quantify subtle interval changes between successive whole-body bone scans because of many variations such as intensity, geometry, and morphology. In this paper, we present the most effective method of image enhancement based on histograms, which may assist radiologists in interpreting successive whole-body bone scans effectively. Forty-eight successive whole-body bone scans from 10 patients were obtained and evaluated using six methods of image enhancement based on histograms: histogram equalization, brightness-preserving bi-histogram equalization, contrast-limited adaptive histogram equalization, end-in search, histogram matching, and exact histogram matching (EHM). Comparison of the results of the different methods was made using three similarity measures peak signal-to-noise ratio, histogram intersection, and structural similarity. Image enhancement of successive bone scans using EHM showed the best results out of the six methods measured for all similarity measures. EHM is the best method of image enhancement based on histograms for diagnosing successive whole-body bone scans. The method for successive whole-body bone scans has the potential to greatly assist radiologists quantify interval changes more accurately and quickly by compensating for the variable nature of intensity information. Consequently, it can improve radiologists' diagnostic accuracy as well as reduce reading time for detecting interval changes.

Background: Currently the best intervention after injection of 99mTc-HDP is drinking plenty of fluid with no specific amount or time limit. The previous studies did show some but not significant improvement between image qualities of patients who drank water compared to those who did not drink. We aim to investigate if increased and more rapid fluid intake results in better image quality. Methods: In this study, all patients who had a bone scintigram were questioned about how much fluid they had in the two hours between injection and imaging, and how much of that was taken in the first hour post injection The images were acquired two hour +/- 10min post intravenous injection of 99mTc-HDP using GE Infinia Hawkeye 4. The operator, equipment and radiopharmaceutical were the same for all studies and quality was assessed by measuring bone to soft tissue ratio using Xeleris 3 program. Results: 146 adult patients with total of 156 images who had bone scan imaging at Auckland Radiology Group were assessed. These patients aged between 30 and 78 (median, 51), were mostly men (61%) and 10 (about 6.5%) had two bone scans. The overall result, although a small change, was in favor of increasing fluid intake in the first hour which improved the bone to soft tissue ratio by an average of 2.5%. This was especially noticeable in patients who had two scans within few months of each other which could be compared, in this group nearly all the variables remain the same except the amount of fluid intake, this group had an average improvement of 9.65% (range, 2%-19.5%). Conclusion: Rapid hydration post injection of 99mTc-HDP showed a small contribution on the quality of bone scan images however this together with increased likelihood of voiding earlier on post injection, which contributes to reducing radiation dose to the bladder wall, makes this method appealing to adopt for routine use.

The aim of this program has been to improve the performance of positron emission tomography (PET) to achieve high resolution with high sensitivity. Towards this aim, the authors have carried out the following studies: (1) explored new techniques for detection of annihilation radiation including new detector materials and system geometries, specific areas that they have studied include--exploration of factors related to resolution and sensitivity of PET instrumentation including geometry, detection materials and coding, and the exploration of technique to improve the image quality by use of depth of interaction and increased sampling; (2) complete much of the final testing of PCR-II, an analog-coded cylindrical positron tomograph, developed and constructed during the current funding period; (3) developed the design of a positron microtomograph with mm resolution for quantitative studies in small animals, a single slice version of this device has been designed and studied by use of computer simulation; (4) continued and expanded the program of biological studies in animal models. Current studies have included imaging of animal models of Parkinson`s and Huntington`s disease and cancer. These studies have included new radiopharmaceuticals and techniques involving molecular biology.

Endoscopy is a widely practiced technique across the globe, utilized to envision the gastrointestinal (GI) tract of the human body without causing harm. In GI endoscopy, images affected by noise may not be helpful to support a visual diagnosis of the mucosal surface at good quality. In such advanced imaging systems, image quality enhancement becomes particularly beneficial. In this study, a non-invasive numerical method of image enhancement is examined to improve the image quality metrics as is critical in GI imaging. A unique approach of weighting and thresholding is examined in this study, where the weighting and thresholding play a significant role in image enhancement. Deviations from the proposed weighting scheme results in the reduction of the peak signal to noise ratio (PSNR) among other key metrics. The proposed method evaluated on eight datasets are expounded to produce optimal performance, particularly in that of the PSNR, entropy and contrast over the state-of-the-art (SOA) enhancement algorithms. The proposed method yields a universal image quality index of 93 %, a structural similarity of 86 % and that of 25 %, 11 %, 19 % and 30 % of PSNR, entropy, contrast, and distortion metric enhancements on average in comparison with the SOA, contributing to the improved quality of the resultant frame aiding to view image features at higher detail and overall quality, both quantitively and qualitatively. This in conjunction with higher optical magnification and faster graphics processing units (GPU’s) may be beneficial for a real-time examination of the mucosal surface of the GI tract at superior quality.

Various studies have compared the detection of functioning residual thyroid tissue after thyroidectomy using radioiodine whole-body (WB) imaging following preparation of patients with injections of recombinant human thyroid-stimulating hormone (rhTSH) and thyroid hormone withdrawal (THW). However, metastases may have radiopharmacokinetics different from normal thyroid tissue. The objective of this study was to evaluate these 2 methods of patient preparation for the detection of metastases from differentiated thyroid cancer (DTC) using (131)I WB imaging and (124)I PET. A prospective study approved by the institutional review board was conducted at Washington Hospital Center from 2006 to 2010 recruiting patients who had DTC, were suspected of having metastasis from DTC (e.g., elevated thyroglobulin level without thyroglobulin antibodies, positive results on recent fine-needle aspiration, suspected enlarging mass, and abnormal findings suggesting metastasis on a diagnostic study) and were referred for (131)I WB dosimetry. All patients subsequently underwent both (131)I WB imaging and (124)I PET performed using the same preparation. All foci of uptake identified on these scans were categorized in a masked manner by consensus of 2 physicians in the following manner: 1, definite physiologic uptake or artifact; 2, most likely physiologic uptake or artifact; 3, indeterminate; 4, most likely locoregional metastases in the neck bed; 5, most likely distant metastases; or 6, definite distant metastases. Foci categorized as 4, 5, and 6 were considered positive for functioning metastases. Of 40 patients evaluated, 24 patients were prepared with rhTSH and 16 with THW. No statistical difference was noted between the 2 groups for any of the parameters evaluated, including serum thyroglobulin. The percentages of patients with positive foci detected on the rhTSH (131)I and THW (131)I WB scans were 4% (1/24) and 63% (10/16), respectively (P < 0.02). The number of foci detected on the rhTSH (131)I and THW (131)I WB scans were 2 and 58, respectively (P < 0.05). When (124)I PET was used for imaging, the percentages of patients with foci detected on the rhTSH and THW scans were 29% (7/24) and 63% (10/16), respectively (P < 0.03). The number of foci detected on the rhTSH and THW scans were 17 and 117, respectively (P < 0.03). Significantly more foci of metastases of DTC may be identified in patients prepared with THW than in patients prepared with rhTSH.

The aim of this study was to investigate the value of gallium-67 and thallium-201 whole-body and single-photon emission tomography (SPET) images in long-term dialysis patients in whom dialysis-related beta 2-microglobulin amyloid (beta 2-MA) was clinically suspected. Twenty-three patients who had received dialysis for at least 10 years were included in the study. A technetium-99m methylene diphosphonate (MDP) whole-body scan was performed in all of the patients. If there was any MDP accumulation in the articular and/or peri-articular region, 67Ga and 201Tl whole-body and SPET images were then acquired. If any 67Ga and/or 201Tl uptake was observed, a CT-guided biopsy was done. In those patients who had articular and/or peri-articular uptake of 99mTc MDP, 67Ga and/or 201Tl and who were pathologically proven to have beta 2-MA, 99mTc MDP, 67Ga and 201Tl whole-body scans and SPET were carried out again, both 3 months and 1 year after initiation of treatment. This served to evaluate the therapeutic effect and allowed comparison with the clinical findings. Of the 23 patients, eight had abnormal 99mTc MDP uptake. Among these eight, six had intense 99mTc MDP, 67Ga and 201Tl uptake in the articular and peri-articular regions before medication. Three months after the start of treatment, there were very marked decreases in uptake on both the 67Ga and 201Tl scans but less obvious changes in uptake of 99mTc-MDP. In comparison with the other clinical manifestations such as limitation in range of motion, the more the painful disability improved, the less was the uptake on both 67Ga and 201Tl scans. There were virtually no differences in uptake pattern between the three scans of each radiopharmaceutical obtained for each patient in both 3 months and 1 year after initial of treatment. It is concluded that 99mTc-MDP whole-body bone scan can both detect active and pre-existing inactive deposits of beta 2-MA. 67Ga and 201Tl scans are helpful to differentiate active from inactive deposits of beta 2-MA and to evaluate the therapeutic effect on these patients. SPET images are usually needed to distinguish articular and periarticular lesions from bone lesions.

In this pilot study, we have proposed and evaluated pipelined application of the dynamic stochastic resonance (DSR) algorithm and block-matching 3D (BM3D) filter for the enhancement of nuclear medicine images. The enhanced images out of the pipeline were compared with the corresponding enhanced images obtained using individual applications of DSR and BM3D algorithm. Twenty 99m-Tc MDP bone scan images acquired on SymbiaT6 SPECT/CT gamma camera system fitted with low-energy high-resolution collimators were exported in DICOM format to a personal computer and converted into PNG format. These PNG images were processed using the proposed algorithm in MATLAB. Two nuclear medicine physicians visually compared each input and its corresponding three enhanced images to select the best-enhanced image. The image quality metrics (Brightness, Global Contrast Factor (GCF), Contrast per pixel (CPP), and Blur) were used to assess the image quality objectively. The Wilcoxon signed test was applied to find a statistically significant difference in Brightness, GCF, CPP, and Blur of enhanced and its input images at a level of significance. Images enhanced using the pipelined application of SR and BM3D were selected as the best images by both nuclear medicine physicians. Based on Brightness, Global Contrast Factor (GCF), CPP, and Blur, the image quality of our proposed pipeline was significantly better than enhanced images obtained using individual applications of DSR and BM3D algorithm. The proposed method was found to be very successful in enhancing details in the low count region of input images. The enhanced images were bright, smooth, and had better target-to-background ratio compared to input images. The pipelined application of DSR and BM3D algorithm produced enhancement in nuclear medicine images having following characteristics: bright, smooth, better target-to-background ratio, and improved visibility of details in the low count regions of the input image, as compared to individual enhancements by application of DSR or BM3D algorithm.

Speech enhancement is an important pre-processing step in a wide diversity of practical fields related to speech signals, and many signal-enhancement methods, such as fixed beamforming and adaptive beamforming, have already been proposed for speech enhancement. However, lack of comprehensive and quantitative performance evaluation of current enhancement methods when multi-speeches exist simultaneously, it is difficult to choose an appropriate enhancement method in a practical application. This work aims to study the implementation of several enhancement methods for multi-speech enhancement in indoor environment of T60 = 0 s and T60 = 0.3 s. We first propose and compare two types of enhancement approaches. The first type is the basic enhancement methods, including the delay-and-sum beamforming (DSB), minimum variance distortionless response (MVDR), linearly constrained minimum variance (LCMV), and independent component analysis (ICA); The second type is the improved enhancement methods, including the robust MVDR and LCMV, realized by eigen decomposition and diagonal loading. In addition, the online enhancement performance based on the iteration of single-frame speech signals is then researched. The experimental results show that the enhancement effect of LCMV and ICA is relatively more stable in the case of the basic enhancement methods; in the case of the improved enhancement algorithms, the methods which employed diagonal loading iterations are better. In the case of the online enhancement, the DSB with frequency masking yields the best performance on the signal-to-interferences ratio (SIR) and possesses the capacity to suppress interferences.