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Position emission tomography (PET) is widely used in clinics and research due to its quantitative merits and high sensitivity, but suffers from low signal-to-noise ratio (SNR). Recently convolutional neural networks (CNNs) have been widely used to improve PET image quality. Though successful and efficient in local feature extraction, CNN cannot capture long-range dependencies well due to its limited receptive field. Global multi-head self-attention (MSA) is a popular approach to capture long-range information. However, the calculation of global MSA for 3D images has high computational costs. In this work, we proposed an efficient spatial and channel-wise encoder-decoder transformer, Spach Transformer, that can leverage spatial and channel information based on local and global MSAs. Experiments based on datasets of different PET tracers, i.e., $^{18}$F-FDG, $^{18}$F-ACBC, $^{18}$F-DCFPyL, and $^{68}$Ga-DOTATATE, were conducted to evaluate the proposed framework. Quantitative results show that the proposed Spach Transformer can achieve better performance than other reference methods., 10 pages

Novel diagnostic and therapeutic radiopharmaceuticals are increasingly becoming a central part of personalized medicine. Continued innovation in the development of new radiopharmaceuticals is key to sustained growth and advancement of precision medicine. Artificial intelligence (AI) has been used in multiple fields of medicine to develop and validate better tools for patient diagnosis and therapy, including in radiopharmaceutical design. In this review, we first discuss common in silico approaches and focus on their utility and challenges in radiopharmaceutical development. Next, we discuss the practical applications of in silico modeling in design of radiopharmaceuticals in various diseases.

We evaluated a cysteine cathepsin-activatable optical imaging probe (LUM015) with improved kinetics relative to larger macromolecules for detection and characterization of colorectal cancer (CRC), and thereby assessed its potential use in fluorescence-guided colonoscopy. We showed that LUM015 is stable in plasma. In-vitro studies demonstrated selectivity of LUM015 for targeting cathepsins; there was robust increase in emitted fluorescence signal from the cathepsin overexpressing HT-29 CRC cells within 1-5 minutes after incubation with LUM015 compared to the cells incubated with combination of LUM015 and a pan-protease inhibitor (as negative control). Biodistribution, differential accumulation of the probe in the tumor and tumor-to-background fluorescence signal ratio of LUM015 were compared to ProSense680, a commercially available protease-activatable optical imaging probe, over 24 hours after intravenous injection of the probes in nude mice with subcutaneously implanted HT-29 tumors. LUM015 showed distinct kinetics compared to ProSense680 with time to peak signal for subcutaneous tumor-to-colon ratio of 3.3±0.3 (mean ± SD) at 4-8 hours compared to 2.9±0.2 at 24 hours, respectively (n=8 for each group). Near-infrared fluorescence imaging and dual channel colonoscopy of the mice with orthotopic colon tumors showed tumor-to-colon ratio of 3.7±0.2 in HT-29 tumors (n=4), 2.8±0.1 in genetically engineered mice with APC(KO)Kras(LSL-G12D)p53(flox/flox) mutation (n=4), and 4.1±0.1 in mice with APC(LoxP/LoxP)Msh2(LoxP/LoxP) mutation (n=4) at 6 hours after LUM015 administration. Immunohistochemistry and laser confocal microscopy of the extracted tumors confirmed high expression of cysteine cathepsins in all colon tumor types tested. Optical imaging with cathepsin-activatable LUM015 in multiple models of CRC highlights its potential for increasing the efficacy of CRC screening and therapeutic procedures.

This prospective pilot study provides a dynamic whole body PET/MR image database, clinical safety, biodistribution profile and dosimetry of 68Ga-DOTATOC in healthy subjects, to establish a baseline and standard reference for its use in diagnosis and treatment response evaluation among patients with somatostatin receptor expressing neoplastic diseases. Dynamic whole body PET/MR imaging was performed in 12 healthy subjects (male/female: 8/4) after injection of 242.39 ± 53.38 MBq (mean ± SD) 68Ga-DOTATOC. Images were acquired 15, 60, 120, and 240 minutes post injection. Subjects were assessed at baseline and after 68Ga-DOTATOC PET/MR by monitoring vital signs, 12-lead electrocardiograms, complete blood count, comprehensive metabolic panel, and urinalysis. Adverse events were monitored for one week after injection. Organ dosimetry was estimated using OLINDA/EXM 1.1 software. Radiotracer was exclusively eliminated via urinary tract (18.8 ± 1.0% of injected dose within 4 hours) and no redistribution was observed. Bladder wall, spleen and kidneys received the highest radiation exposure (0.64 ± 0.1 mSv/MBq, 0.29 ± 0.14 mSv/MBq, and 0.1 ± 0.02 mSv/MBq, respectively). Mean effective dose yielded 0.048 ± 0.007 mSv/MBq. No adverse events were reported during the one-week follow-up period. Follow-up laboratory tests and electrocardiograms showed no changes compared to the baseline. The use of MRI provided valuable anatomical information and eliminated the risk of radiation exposure compared to CT.

The interest in (68)Gallium labeled PET probes continues to increase around the world. Widespread use in Europe and Asia has led to great interest for use at numerous sites in the US. One barrier to entry is the cost of the automated synthesis units for relatively simple labeling procedures. We describe the construction and testing of a relatively low-cost automated (68)Ga-labeling unit for human-use. We provide a guide for construction, including part lists and synthesis timelists to facilitate local implementation. Such inexpensive systems could help increase use around the globe and in the US in particular by removing one of the barriers to greater widespread availability. The developed automated synthesis unit reproducibly synthesized (68)Ga-DOTATOC with average yield of 71 ± 8% and a radiochemical purity ≥ 95% in a synthesis time of 25 ± 1 minutes. Automated product yields are comparable to that of manual synthesis. We demonstrate in-house construction and use of a low-cost automated synthesis unit for labeling of DOTATOC and similar peptides with (68)Gallium.

This pilot study investigates the value of baseline total lesion glycolysis (TLG) in (18)F-FDG PET/CT scans for prediction of progression-free survival (PFS) in patients with Diffuse Large B-Cell Lymphoma (DLBCL). We also evaluate the role of other quantitative parameters measured at baseline and interim PET/CT for prediction of PFS. A retrospective review (2003-2010) of patients with DLBCL who underwent (18)F-FDG PET/CT before, after cycle two, and after completion of R-CHOP treatment, identified 84 patients. Twenty patients fulfilled the inclusion criteria. Standardized uptake values (SUVmax and SUVmean), total metabolic tumor volume (TMTV), and TLG were measured in baseline and interim PET/CT. Relationship between quantitative parameters and PFS was statistically analyzed using Log-rank test and univariate Cox-regression analysis. Of 20 patients (F/M: 7/13, range: 20-73 years), six patients (30%) developed recurrence after chemotherapy (mean follow-up: 51.35±17.05 months, range: 12-81 months). Results of statistical analysis showed TLG as the only discriminator of recurrence at baseline (cut-point: 704.77 g, HR: 11.21, CI: 1.29-97, P=0.02). Among the interim PET/CT parameters, SUVmean (cut -point: 2.07, HR: 6.31, CI: 1.25-31.61), SUVmax (cut-point: 2.3, HR: 6.31, CI: 1.25-31.61), and TLG (cut-point: 96.5 g, HR: 6.38, CI: 1.29 - 31.61) could all help predict PFS (P0.05). Although not routinely reported, high baseline TLG may be a useful index to identify patients with DLBCL who are at increased risk for relapse after conventional R-CHOP. If confirmed in larger prospective studies, this may allow the selection of alternate therapeutic choices at the onset of treatment.

To illustrate mechanisms of spine fractures and the pattern of spinal injuries characterized by the major mechanisms in urban population of Iran.Data regarding spinal injuries including demographics, mechanism and level of spinal injury, abbreviated injury score, associated injuries and final fate of the patients were extracted from the Iranian national trauma registry database from 1999 to 2004.A total of 619 patients with traumatic spine fractures were identified, of whom 68.5% were males. The peak frequency of these injuries occurred in the 21-40 year age-group. Accidental falls and road traffic crashes (RTCs) were the most common mechanisms of spinal fractures (47.2% and 44.1%, respectively). RTCs tended to occur in younger patients compared with accidental falls. The most common spinal region for spinal fracture was the lumbar spine (53.63%). Cervical spine fractures were significantly more common in RTCs, while lumbar spine fractures were more common in accidental falls (P less than 0.001). A total of 171 (27.6%) patients had associated non-spinal injuries, of whom 127 had associated extremity injuries, and 55 had head injuries. Thirty-six (5.6%) patients had spinal cord injury (SCI).The injury severity score of the RTC group was significantly higher than that of accidental falls (P equal to 0.002). Fifteen (4%) patients died of traumatic injuries. The rate of death was significantly higher in RTCs compared with accidental falls (5.1% vs 2.1%, P equal to 0.039).The patterns of spinal fractures are similar to those reported from developed countries. RTCs tend to affect the younger age population and are associated with a higher degree of associated injuries and mortality than accidental falls. Therefore preventive strategies should be based on reduction of the number and severity of RTCs.

Purpose Methods and Materials Results Conclusion References Personal Information, Purpose: PET/CT has a well established role inthe assessmentof response to therapy in oncology.For a precise evaluation of therapy response, the visualinterpretation of PET/CT DICOM images as well as the measurement of quantitative parameters are necessary...

ObjectiveTo determine the patterns of traumatic extremity injuries leading to amputation in Iran.MethodsData of Iranian National Trauma Project was used to identify patients with upper and lower extremity traumas undergoing amputation. This project was conducted in 8 major cities during 2000-2004.ResultsOf 17 753 traumatic patients, 164 (0.92%) had injuries to theextremities that resulted in the limb amputation. Of these, 143 (87.2%) were men. The patient's mean age was 29.0 years ± 15.4 years and the highest incidence was seen in the age group of 21 to 30 years (34.1%). One hundred and four cases were occupational accidents (63.4%). Blunt trauma was in 54.9% of the cases. The most common reasons for amputation were respectively stabbings (37.8%) and crush injuries (31.7%). Amputation of hand fingers was the most frequent type of amputation (125 cases, 76.2 %). One patient died from severe associated injuries.ConclusionsThis study shows the patterns of traumatic limb amputation in Iran, a developing country. Results of this study may be used in preventive strategic planning.

Background: MR is an important imaging modality for evaluating musculoskeletal malignancies owing to its high soft tissue contrast and its ability to acquire multiparametric information. PET provides quantitative molecular and physiologic information and is a critical tool in the diagnosis and staging of several malignancies. PET/MR, which can take advantage of its constituent modalities, is uniquely suited for evaluating skeletal metastases. We reviewed the current evidence of PET/MR in assessing for skeletal metastases and provided recommendations for its use. Methods: We searched for the peer reviewed literature related to the usage of PET/MR in the settings of osseous metastases. In addition, expert opinions, practices, and protocols of major research institutions performing research on PET/MR of skeletal metastases were considered. Results: Peer-reviewed published literature was included. Nuclear medicine and radiology experts, including those from 13 major PET/MR centers, shared the gained expertise on PET/MR use for evaluating skeletal metastases and contributed to a consensus expert opinion statement. [18F]-FDG and non [18F]-FDG PET/MR may provide key advantages over PET/CT in the evaluation for osseous metastases in several primary malignancies. Conclusion: PET/MR should be considered for staging of malignancies where there is a high likelihood of osseous metastatic disease based on the characteristics of the primary malignancy, hight clinical suspicious and in case, where the presence of osseous metastases will have an impact on patient management. Appropriate choice of tumor-specific radiopharmaceuticals, as well as stringent adherence to PET and MR protocols, should be employed. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.