GPU-accelerated three-dimensional reconstruction method of the Compton camera and its application in radionuclide imaging

A novel and fast three-dimensional reconstruction method for a Compton camera and its performance in radionuclide imaging is proposed and analyzed in this study. The conical surface sampling back-projection method with scattering angle correction(CSS-BP-SC) can quickly perform the back-projection process of the Compton cone and can be used to precompute the list-mode maximum likelihood expectation maximization(LM-MLEM). A dedicated parallel architecture was designed for the graphics processing unit acceleration of the back-projection and iteration stage of the CSS-BP-SC-based LM-MLEM. The imaging results of the two-point source Monte Carlo(MC) simulation demonstrate that by analyzing the full width at half maximum along the three coordinate axes, the CSS-BP-SC-based LM-MLEM can obtain imaging results comparable to those of the traditional reconstruction algorithm, that is, the simple back-projection-based LM-MLEM. The imaging results of the mouse phantom MC simulation and experiment demonstrate that the reconstruction results obtained by the proposed method sufficiently coincide with the set radioactivity distribution, and the speed increased by more than 664 times compared to the traditional reconstruction algorithm in the mouse phantom experiment. The proposed method will further advance the imaging applications of Compton cameras.

RADIONUCLIDE WHOLE BODY BONE IMAGING IN THE DIAGNOSIS OF SKELETAL METASTASES

Of 628 patients with extra-osseous malignancies diagnosed by surgery and/or pathology, 207 (33.0%) were identified as having skeletal metastasis by bone imaging. There was statistical significant difference in the incidence of metastasis in different malignancies (P<0.02). The metastatic rates of nasopharyn-geal, lung, prostate and breast cancers were higher than gastrointestinal, kidney, and other malignancies. There was significant differences in the different sites of skeletal metastasis (P<0.01). They were thorax, spine, pelvis, limbs and skull in order of incidence. Solitary metastatic rate was 15.9%. Biopsy is advised for patients suspected to have metastatic disease but with only one single 'hot spot' in skeletal imaging, particularly in the rib.

Classification of hepatobiliary scintigraphy patterns in segmented gallbladder according to anatomical discordance

BACKGROUND Hepatobiliary scintigraphy(HBS)is a useful diagnostic imaging technique that uses radiotracers to evaluate the function of the gallbladder(GB)and biliary system.In segmented GB,some HBS images reveal a discordant GB boundary as compared to anatomical images.AIM To evaluate the characteristics of HBS in segmented GB and determine the clinical relevance according to HBS characteristics.METHODS A total of 268 patients with chronic cholecystitis,gallstones,or biliary colic symptoms who underwent HBS between 2011 and 2020 were enrolled.Segmented GB was defined as segmental luminal narrowing of the GB body on computed tomography(CT)or magnetic resonance(MR)images,and HBS was examined 1 mo before or after CT or MR.Segmented GB was classified into 3 types based on the filling and emptying patterns of the proximal and distal segments according to the characteristics of HBS images,and GB ejection fraction(GBEF)was identified:Type 1 was defined as a normal filling and emptying pattern;Type 2 was defined as an emptying defect on the distal segment;and Type 3 was defined as a filling defect in the distal segment.RESULTS Segmented GB accounted for 63 cases(23.5%),including 36 patients(57.1%)with Type 1,18 patients(28.6%)with Type 2,and 9 patients(14.3%)with Type 3 emptying pattern.Thus,approximately 43%of HBS images showed a discordant pattern as compared to anatomical imaging of segmented GB.Although there were no significant differences in clinical symptoms,rate of cholecystectomy,or pathological findings based on the type,most gallstones occurred in the distal segment.Reported GBEF was 62.50%±24.79%for Type 1,75.89%±17.21%for Type 2,and 88.56%±7.20%for Type 3.Type 1 showed no difference in reported GBEF compared to the non-segmented GB group(62.50%±24.79%vs 67.40%±21.78%).In contrast,the reported GBEF was higher in Types 2 and 3 with defective emptying and filling when compared to Type 1(80.11%±15.70%vs 62.57%±24.79%;P=0.001).CONCLUSION In segmented GB,discordance in the filling patterns detected by HBS and anatomical imaging could lead to misinterpretation of GBEF.For this reason,clinicians should be cautious when interpreting HBS results in patients with segmented GB.

Technetium-99m-labeled macroaggregated albumin lung perfusion scan for diagnosis of hepatopulmonary syndrome: A prospective study comparing brain uptake and whole-body uptake

BACKGROUND Hepatopulmonary syndrome (HPS) is an arterial oxygenation defect induced by intrapulmonary vascular dilatation (IPVD) in the setting of liver disease and/or portal hypertension.This syndrome occurs most often in cirrhotic patients(4%-32%) and has been shown to be detrimental to functional status,quality of life,and survival.The diagnosis of HPS in the setting of liver disease and/or portal hypertension requires the demonstration of IPVD (i.e.,diffuse or localized abnormally dilated pulmonary capillaries and pulmonary and pleural arteriovenous communications) and arterial oxygenation defects,preferably by contrast-enhanced echocardiography and measurement of the alveolar-arterial oxygen gradient,respectively.AIM To compare brain and whole-body uptake of technetium for diagnosing HPS.METHODS Sixty-nine patients with chronic liver disease and/or portal hypertension were prospectively included.Brain uptake and whole-body uptake were calculated using the geometric mean of technetium counts in the brain and lungs and in the entire body and lungs,respectively.RESULTS Thirty-two (46%) patients had IPVD as detected by contrast-enhancedechocardiography.The demographics and clinical characteristics of the patients with and without IPVD were not significantly different with the exception of the creatinine level (0.71±0.18 mg/dL vs 0.83±0.23 mg/dL;P=0.041),alveolararterial oxygen gradient (23.2±13.3 mmHg vs 16.4±14.1 mmHg;P=0.043),and arterial partial pressure of oxygen (81.0±12.1 mmHg vs 90.1±12.8 mmHg;P=0.004).Whole-body uptake was significantly higher in patients with IPVD than in patients without IPVD (48.0%±6.1%vs 40.1%±8.1%;P=0.001).The area under the curve of whole-body uptake for detecting IPVD was significantly higher than that of brain uptake (0.75 vs 0.54;P=0.025).The optimal cut-off values of brain uptake and whole-body uptake for detecting IPVD were 5.7%and 42.5%,respectively,based on Youden’s index.The sensitivity,specificity,and accuracy of brain uptake> 5.7%and whole-body uptake> 42.5%for detecting IPVD were23%,89%,and 59%and 100%,52%,and 74%,respectively.CONCLUSION Whole-body uptake is superior to brain uptake for diagnosing HPS.

Evaluation of ^(99m)Tc Labeled Diadenosine Tetraphosphate as an Atherosclerotic Plaque Imaging Agent in Experimental Models

The potential of ^99mTc labeled P^1, P^4-di （adenosine-5 ＇ ）-tetraphosphate （Ap4A） for imaging experimental atherosclerotic plaques was evaluated in New Zealand white （NZW） rabbits. To label the ^99mTc to Ap4A, stannous tartrate solution was used. ^99mTc-Ap4A was purified on a Sephadex G-25 column. The radiochemistry purities of ^99mTc-Ap4A were 85% to 91%. Biodistribution study revealed ^99mTc-Ap4A cleared from blood rapidly. Thirty min after ^99mTc-Ap4A administrated on NZW atherosclerotic rabbits, lesion to blood （target/blood, T/B） ratio was 3. 17 ±1.27, and lesions to normal （target/non-target, T/NT） ratio was 5.23 ±1.87. Shadows of atherosclerotic plaques were clearly visible on radioautographic film. Aortas with atherosclerotic plaques also could be seen on ex vivo gamma camera images. Atherosclerotic abdominal aortas were clearly visible on in vivo images 15 min to 3 h after ^99mTc-Ap4A administration. ^99mTc-labeled Ap4A can be used for rapid noninvasive detection of experimental atherosclerotic plaque.

A novel denoising framework for cerenkov luminescence imaging based on spatial information improved clustering and curvature-driven diffusion

With widely availed clinically used radionuclides,Cer enkov luminescence imaging(CLI)has become a potential tool in the field of optical molecular imaging.However,the impulse noises introduced by high-energy gamma rays that are generated during the decay of radionuclide reduce the image quality significantly,which affects the acauracy of quantitative analysis,as well as the three dimensional reconstruction.In this work,a novel denoising framework based on fuzzy dlustering and curvat ure driven difusion(CDD)is proposed to remove this kind of impulse noises.To improve the accuracy,the F u1zzy Local Information C-Means algorithm,where spatial information is evolved,is used.We evaluate the per formance of the proposed framework sys-tematically with a series of experiments,and the corresponding results demonstrate a better denoising effect than those from the commonly used median filter method.We hope this work may provide a useful data pre processing tool for CLI and its following studies.

Hip prosthetic loosening:A very personal review

Hip prosthetic loosening is often difficult to detect at an early stage,and there has been uncertainty for a long time as to when the loosening occurs and thus to the basic causes.By comparing different diagnostic methods,we found that loosening is best defined as prosthetic migration and measured by radiostereometric analysis.Convincing evidence indicates that poor interlock,poor bone quality,and resorption of a necrotic bone bed may initiate loosening during or shortly after surgery;this forms the basis of the theory of early loosening.Biomechanical factors do affect the subsequent progression of loosening,which may increase subclinically during a long period of time.Eventually,the loosening may be detected on standard radiographs and may be interpreted as late loosening but should to be interpreted as late detection of loosening.The theory of early loosening explains the rapid early migration,the development of periprosthetic osteolysis and granulomas,the causality between wear and loosening,and largely the epidemiology of clinical failure of hip prostheses.Aspects discussed are definition of loosening,the pattern of early migration,the choice of migration threshold,the current understanding of loosening,a less exothermic bone cement,cemented taper-slip stems,a new exciting computed tomography-based technique for simpler implant migration studies,and research suggestions.

Radionuclide techniques for evaluating dilated cardiomyopathy and ischemic cardiomyopathy

To assess the clinical significance of radionuclide techniques in evaluating dilated cardiomyopathy (DCM) and ischemic cardiomyopathy (CAD CM) Methods 28 patients with DCM and 55 patients with CAD CM were studied All patients underwent 99m Tc MIBI myocardial perfusion SPECT and 18 F FDG myocardial metabolic PET 78 patients had 99m Tc RBC radionuclide ventriculography and 68 patients had coronary angiography Results The results of 23 patients (82%) with DCM showed mild and non segmental distribution perfusion abnormalities 52 patients with CAD CM (95%) showed perfusion abnormalities that distributed along the coronary vessel territories Significant perfusion defects were found in 4 patients with DCM (14%) and 45 patients with CAD CM (82%) ( P <0 01) The average perfusion score was 4 5±2 6 in DCM and 9 6±2 5 in CAD CM and the area of diminished perfusion was significantly smaller in DCM than in CAD CM ( P <0 001) Two patients with DCM and 18 patients with CAD CM had metabolic defects The patterns of perfusion/metabolic imaging showed mismatch in most patients with CAD CM but match in most patients with DCM The LVEF in patients with DCM and CAD CM was both decreased but the decreases were not statistically different between DCM and CAD CM The RVEF in patients with DCM was significantly lower than that in patients with CAD CM (32 4%±13 9% vs 40 9%±15 4%, P<0 05) Conclusion The radionuclide techniques are helpful for distinguishing DCM from CAD CM The segmental perfusion abnormality and RVEF are the most important factors for differentiation of DCM from CAD CM

Development and evaluation of a double-plane detector system for multi-radionuclide imaging

Purpose To develop a multi-radionuclide imaging system with a flexible and compact structure that has a potential for breast and other applications,and to evaluate its performances under both positron emission tomography and single photon emission imaging conditions.Methods The plane detector was composed of 5×6 blocks with an effective detection area of 168.6 mm×202.4 mm.Each block consisted of a 16×16 LYSO array.The pixel size is 1.9 mm×1.9 mm×15 mm.An 8×8 silicon photomultiplier(SiPM)array with SensL’s C-30035 sensors was coupled to the LYSO array,separated by a 1.5-mm-thick glass.To minimize the influence of temperature on the detector,the active part of the front-end electronics was kept away from SiPMs.Self-designed data acquisition system and reconstruction software were utilized to evaluate the performances of the whole system.Results All the blocks had excellent pixels identification.An average energy resolution of 11.39%for 511 keV and 21.37%for 140 keV was obtained.In the PET mode,the best spatial resolution was better than 2 mm and the system sensitivity reached up to 11.05%at 60 mm distance.In the single photon emission imaging mode,a spatial resolution better than 3 mm was obtained.Conclusion The results indicated that the system has a good overall performance and can be used in breast imaging and other general PET applications.It also has the potential to be used for single photon emission imaging.In pursuit of a better spatial resolution of cross-plane,PSF and DOI technology will be developed in the next work.For specific applications,further improvement of the detector system such as performance evaluation with phantoms will be carried out.

Inorganic imaging nanoprobes for breast cancer diagnosis

Breast cancer is one of the most prevalent cancers worldwide,and early diagnosis and screening are vital to its successful treatment.Although medical imaging methods can assist in the early detection of breast cancer,imaging methods that are currently used for clinical diagnosis have drawbacks,such as low sensitivity and accuracy.Contrast agents are often used in diagnostic imaging to address these drawbacks.Nanocontrast agents have attracted considerable attention in recent years due to their unique physicochemical characteristics.Among these agents,inorganic nanoprobes have been substantially developed through improvements in synthesis techniques and pairings with other organic molecules.This paper mainly summarizes the specific applications of inorganic nanoprobes in the magnetic resonance imaging,fluorescence imaging,radionuclide imaging,and bimodal/multimodal imaging of breast cancer.

Nanogels as Contrast Agents for Molecular Imaging

Nanogels （NGs） as soft nanosized materials have gained a variety of interests in biomedical fields. The versatile NG scaffolds with 3-dimensional spherical shape, high loading efficiency, tunable surface functionalization, and excellent biocompatibility afford their uses as carrier to load mono- or multi-mode molecular imaging contrast agents （CAs）. This review summarizes the synthesis routes and applications of NGs as CAs for molecular imaging applications including magnetic resonance （MR）, computed tomography （CT）, radionuclide, optical, and dual/mul- ti-modality imaging.

骨溶解症一例报告

大块骨质溶解症(massive osteolysis),又称GorhamStout综合征、幽灵骨、急性自发性骨吸收、骨淋巴管瘤病、Gorham病等[1],是一种进行性局灶性骨质破坏性病变,1938年Jackson首先描述,1954年Gorham等提出将此病作为一种独立性骨病,认为是一种血管瘤。1974年Thompson则认为此病系骨内血管畸形所致。目前其病因仍不明确,多数认为可能与富血管组织的耗氧量增加导致骨吸收的增加有关[2],也有人持不同观点[3]。

An imaging study using laminin peptide ^(99m) Tc-YIGSR in mice bearing Ehrlich ascites tumour

Background The YIGSR is a pentapeptide, from the laminin-1 of the β1 chain, which can mediate cell adhesion and bind the 67 kD laminin receptor. The purpose is to evaluate the usefulness of 99m Tc-YIGSR, a novel tumour radiotracer, in the receptor imaging of Ehrlich ascites tumour. Methods Using S-Acetly-NH_3-MAG_3 as chelate, YIGSR, a pentapeptide from laminin, was tagged with 99m Tc. 99m Tc-YIGSR was detected in the tumour group bearing Ehrlich ascites tumour and blocked group. Tumour, normal, inflammatory and blocked groups were imaged. Results Through reverse phase Sep-Pak C_ 18 chromatogram, it was revealed that YIGSR could conjugate with S-Acetly -NH_3-MAG_3, and be radiolabelled at room temperature and neutral pH with a radiolabelling yield of 62%, and of 4% without chelate. 99m Tc-YIGSR was rapidly cleared from kidney, then liver. The imaging findings showed tumour tissue accumulated initial radioactivity at fifteen minutes after injection in the tumour group, and the uptake increased to peak at three hours with a tumour/muscle ratio (T/M) of 11.36, then cleared slowly to a T/M of 7.50 at eight hours. The tumour uptake of radiotracer in blocked group was significantly lower with T/M of 4.61 at three hours and 0.89 at eight hours. The T/M was only 3.72 at three hours and 1.29 at eight hours after injection in inflammatory group. Compared with inflammatory group and control obstructive group, the ratio of T/M in tumour group was significantly different ( P <0.001). Conclusions Using S-Acetly-NH_3-MAG_3, we radiolabelled YIGSR with 99m Tc. 99m Tc-YIGSR possesses many merits of tumour imaging: rapid visualization, high sensitivity and specificity, and satisfactory target/nontarget ratio. Our data suggest 99m Tc-YIGSR is a promising tumour radiotracer.

The role of technetium Tc99m-tetrofosmin as head and neck tumor-seeking agent:a preliminary report

Aim:To evaluate the diagnostic value of technetium Tc99m-tetrofosmin(^(99m)Tc-TF)in primary cancers of the head and neck.Methods:Single photon emission computer tomography with planar imaging of the neck for primary site evaluation and whole body scanning for assessment of metastases in 12 patients with newly diagnosed head and neck cancer.Tumor-to-background index(T/Bg)was derived in patients with positive findings(tumor or lymph nodes).Results:The tomographic images showed increased tracer uptake in pathological sites(primary tumor or lymph node)in 9 patients(overall sensitivity 75%).Primary tumor was visualised in 7 patients(sensitivity 58%)and infiltrated lymph nodes in 4 out 7 patients(sensitivity 57%).Mean values for T/Bg index were 5.44±1.28 for primary tumor and 4.25±1.67 for lymph nodes.Mean values for T/Bg index were 4.5±0.71 for patients with in situ and grade I carcinoma and 6.68±0.36 for patients with tumor grade II and III(P=0.034,Mann-Whitney U test).Conclusion:The present study demonstrates that ^(99m)Tc-TF is a valuable radiotracer for head and neck cancer imaging.To determine the potential role of this imaging protocol in clinical practice will require a larger sample size.

Detecting residual ischemia and identifying coronary artery disease after myocardial infarction using dobutamine technetium-99m-MIBI SPECT

To evaluate dobutamine technetium 99m methoxy isobutyl nitrile (sestamibi) single photon emission computed tomography (Dobu ECT) in detecting residual ischemia and identifying coronary vessel disease after myocardial infarction Methods Sixty two patients with confirmed myocardial infarction were studied with Dobu ECT at the time of coronary artery angiography Dobutamine was administered intravenously in incremental rates from 5 to 40?μg· kg 1 ·min 1 at 3 minute intervals At the highest infusion rate, 7 4×10 8 Bq 99m Tc MIBI was injected intravenously, and tomographic imaging was performed after one hour Resting images were taken after 24 hours, with a second dose of 99m Tc MIBI Results The sensitivity of Dobu ECT in detecting residual ischemia of myocardial infarction was 76%, which was higher than dobutamine electrocardiography (Dobu ECG) Regardless of the single , double or triple vessel diseases, Dobu ECT was superior to Dobu ECG in identifying residual ischemia (56% vs 4%, 86% vs 27%, 100% vs 47%, P <0 01, respectively) The incidence of residual ischemia in patients receiving thrombolytic therapy was 67%, lower than patients without thrombolysis (72%) or those with an old myocardial infarction (94%) But the differences were not statistically significant Dobu ECT detected only 56% of ischemias in non infarct related myocardium Eighty two percent of all significantly stenosed vessels were detected with Dobu ECT, and 84% of patients with multivessel disease could be accurately identified The sensitivity of Dobu ECT was significantly greater for detecting severe stenosis over moderate stenosis The sensitivity for detecting stenosis in the right coronary artery was greater than left anterior descending or left circumflex, but its specificity was lower Conclusion Dobu ECT can identify residual ischemia, as well as its location and extent after myocardial infarction Dobu ECT can also accurately detect significantly stenosed vessels