CT VS MR Attenuation Correction: A Systematic Review on PET Image Quality Assessment (Kaedah Pembetulan Pengecilan Menggunakan Data CT dan MR: Kajian Sistematik terhadap Penilaian Kualiti imej PET.) / Jurnal Sains Kesihatan Malaysia

@#This systematic review was conducted to evaluate the image quality performance when implementing computed tomography data (CTAC) or magnetic resonance data for attenuation correction (MRAC) on positron emission tomography (PET) images. The CTAC and MRAC were performed on image from PET/CT and PET/MR scanners, respectively. The systematic review was done based on Preferred Reporting Items for Systematic Reviews (PRISMA). In this study, twelve articles were included from six databases. The image performance was evaluated by overall image quality, contrast, spatial resolution, detectability, standardised uptake value (SUV) and acquisition time. Data was shown as mean ± standard deviation and compared between CTAC and MRAC images to determine which attenuation correction method provides better image quality. Results found that PET-CTAC and PET-MRAC have similar image performance in overall image quality (p=0.93), detectabilty (p=0.84), SUVmean (p=0.84) and SUVmax (p=0.81). Meanwhile, PET-CTAC acquisition time is significantly faster than PET-MRAC by approximately two fold (p <0.05). There were no statistical analyses performed for image contrast, spatial resolution and contrast-noise-ratio due to the insufficient data. In conclusion, although PET/CT is faster than PET/MRI procedure, images yielded from CTAC and MRAC are equivalent to each other. Due to the variation of linear attenuation coefficient for each type of tissue, future review of image quality comparison can be done focusing on specific tissue or region such as soft tissue, bone and lungs to reflect the real impact of CTAC and MRAC on PET image.

Advances in application of CT/MR and PET/MR for target delineation in glioma / 中华放射肿瘤学杂志

Glioma is the most common central nervous system tumor, mainly derived from the interstitial cells of the nervous system, showing diffuse and infiltrative growth, with the characteristics of high morbidity, high postoperative recurrence, high mortality and low cure rate. Currently, radical resection followed by radiotherapy and chemotherapy is the first choice of treatment. Accurate delineation of GTV-T is of significance for precision radiotherapy after surgery. In addition, CT/MR fusion imaging has been commonly used in the delineation of tumor targets in glioma. In recent years, PET/MR has been more and more widely applied in tumors. In this article, the application and differences between PET/MR and CT/MR for target delineation in glioma were reviewed.

Analysis of Risk in Production for PET/MR and Suggestions for Field Inspection / 中国医疗器械杂志

PET/MR is a high-end medical imaging equipment with integrating PET and MR equipment into the highly sophisticated one and has rich clinical and molecular diagnosis functions, can obtain comprehensive information about the human body structure, function and metabolism, is of great value for the diagnosis and treatment of disease improvement. In this paper, through the analysis of existing production risk points on one of the primary stages of the whole product life cycle, combining with the medical device good manufacture practice, some suggestions have been put forward exploratively to field inspection for PET/MR manufacturers. It has certain significance for regulators of medical devices to clear the production risk point and improve verification efficiency during field inspection.

Timing calibration comparison research of integrated TOF-PET/MR / 生物医学工程学杂志

Integrated TOF-PET/MR is a multimodal imaging system which can acquire high-quality magnetic resonance (MR) and positron emission tomography (PET) images at the same time, and it has time of flight (TOF) function. The TOF-PET system usually features better image quality compared to traditional PET because it is capable of localizing the lesion on the line of response where annihilation takes place. TOF technology measures the time difference between the detectors on which the two 180-degrees-seperated photons generated from positron annihilation are received. Since every individual crystal might be prone to its timing bias, timing calibration is needed for a TOF-PET system to work properly. Three approaches of timing calibration are introduced in this article. The first one named as fan-beam method is an iterative method that measures the bias of the Gaussian distribution of timing offset created from a fan-beam area constructed using geometric techniques. The second one is to find solutions of the overdetermination equations set using L1 norm minimization and is called L1-norm method. The last one called L2-norm method is to build histogram of the TOF and find the peak, and uses L2 norm minimization to get the result. This article focuses on the comparison of the amount of the data and the calculation time needed by each of the three methods. To avoid location error of the cylinder radioactive source during data collection, we developed a location calibration algorithm which could calculate accurate position of the source and reduce image artifacts. The experiment results indicate that the three approaches introduced in this article could enhance the qualities of PET images and standardized uptake values of cancer regions, so the timing calibration of integrated TOF-PET/MR system was realized. The fan-beam method has the best image quality, especially in small lesions. In integrated TOF-PET/MR timing calibration, we recommend using fan-beam method.

¹⁸F-FDG PET/MR Refines Evaluation in Newly Diagnosed Metastatic Urethral Adenocarcinoma / 대한핵의학회잡지

We described the clinical impact of ¹⁸F-FDG PET/MR in refining the evaluation of a 39-year-old female with newly diagnosed metastatic urethral adenocarcinoma.We detailed the diagnostic imaging workup focusing our attention on the CT, MR, and ¹⁸F-FDG PET/MR different findings. In this case, ¹⁸F-FDG PET/MR imaging evaluation resulted not only effective but also altered staging and spared additional invasive procedures in the assessment of a metastatic urethral adenocarcinoma. Combining a highly sensitive PET with the increase tissue resolution of MR (PET/MR) may improve abdominal and pelvic lesion detection outperforming PET/CT for this indication.

Potential Clinical Applications of ¹⁸F-Fluorodeoxyglucose Positron Emission Tomography/Magnetic Resonance Mammography in Breast Cancer / 대한핵의학회잡지

The whole-body positron emission tomography (PET)/magnetic resonance (MR) scan is a cutting edge technology providing comprehensive structural information from MR imaging and functional features from PET in a single session. Recent research findings and clinical experience have shown that ¹⁸F-fluorodeoxyglucose (FDG) whole-body PET/MRimaging has a diagnostic performance comparable with or superior to that of PET/CT in the field of oncology, including for breast cancer. In particular, FDG PET/MR mammography in the prone position with the breast hanging in a pendant manner can provide more comprehensive information about the metabolism, anatomy, and functional features of a breast lesion than a whole-body PET/MR scan. This article reports on current state-of-the-art PET/MR mammography in patients with breast cancer and the prospects for potential application in the future.

PET-MR imaging in cranial nerve system disease: present applications and prospects for the future / 中国医学装备

Single nuclear medicine functional imaging (including SPECT and PET) couldn't fully meet the demand of clinical diagnosis because of its own limits, thus the multimodality imaging equipment integrated anatomical and functional images has became the development trend of the nuclear medicine and even the entire medical imaging. Following the earliest SPECT-CT and PET-CT which having been widely used in clinic, the newest PET-MR has also been applied to clinical practice. PET-MR combined MR images with PET function image is substantial to the clinical diagnosis of cerebral nervous system diseases, cardiovascular system diseases and tumor, etc. In this paper, we reviewed the current application situation and prospects of PET-MR in cerebral nervous system diseases.

Diagnosing Lung Nodules on Oncologic MR/PET Imaging: Comparison of Fast T1-Weighted Sequences and Influence of Image Acquisition in Inspiration and Expiration Breath-Hold

OBJECTIVE: First, to investigate the diagnostic performance of fast T1-weighted sequences for lung nodule evaluation in oncologic magnetic resonance (MR)/positron emission tomography (PET). Second, to evaluate the influence of image acquisition in inspiration and expiration breath-hold on diagnostic performance. MATERIALS AND METHODS: The study was approved by the local Institutional Review Board. PET/CT and MR/PET of 44 cancer patients were evaluated by 2 readers. PET/CT included lung computed tomography (CT) scans in inspiration and expiration (CTin, CTex). MR/PET included Dixon sequence for attenuation correction and fast T1-weighted volumetric interpolated breath-hold examination (VIBE) sequences (volume interpolated breath-hold examination acquired in inspiration [VIBEin], volume interpolated breath-hold examination acquired in expiration [VIBEex]). Diagnostic performance was analyzed for lesion-, lobe-, and size-dependence. Diagnostic confidence was evaluated (4-point Likert-scale; 1 = high). Jackknife alternative free-response receiver-operating characteristic (JAFROC) analysis was performed. RESULTS: Seventy-six pulmonary lesions were evaluated. Lesion-based detection rates were: CTex, 77.6%; VIBEin, 53.3%; VIBEex, 51.3%; and Dixon, 22.4%. Lobe-based detection rates were: CTex, 89.6%; VIBEin, 58.3%; VIBEex, 60.4%; and Dixon, 31.3%. In contrast to CT, inspiration versus expiration did not alter diagnostic performance in VIBE sequences. Diagnostic confidence was best for VIBEin and CTex and decreased in VIBEex and Dixon (1.2 ± 0.6; 1.2 ± 0.7; 1.5 ± 0.9; 1.7 ± 1.1, respectively). The JAFROC figure-of-merit of Dixon was significantly lower. All patients with malignant lesions were identified by CTex, VIBEin, and VIBEex, while 3 patients were false-negative in Dixon. CONCLUSION: Fast T1-weighted VIBE sequences allow for identification of patients with malignant pulmonary lesions. The Dixon sequence is not recommended for lung nodule evaluation in oncologic MR/PET patients. In contrast to CT, inspiration versus expiratory breath-hold in VIBE sequences was less crucial for lung nodule evaluation but was important for diagnostic confidence.