Current Medical Imaging - Volume 17, Issue 6, 2021

Background: Coronavirus disease 2019 (COVID-19) is highly contagious and has claimed more than one million lives, besides causing hardship and disruptions. The Fleischner Society has recommended chest X-ray (CXR) in detecting cases at high risk of disease progression, for triaging suspected patients with moderate-to-severe illness, and for eliminating false negatives in areas with high pre-test probability or limited resources. Although CXR is less sensitive than real-- time reverse transcription-polymerase chain reaction (RT-PCR) in detecting mild COVID-19, it is nevertheless useful because of equipment portability, low cost and practicality in serial assessments of disease progression among hospitalized patients. Objective: This study aims to review the typical and relatively atypical CXR manifestations of COVID-19 pneumonia in a tertiary care hospital. Methods: The CXRs of 136 COVID-19 patients confirmed through real-time RT-PCR from March to May 2020 were reviewed. A literature search was performed using PubMed. Results: A total of 54 patients had abnormal CXR whilst the others were normal. Typical CXR findings included pulmonary consolidation or ground-glass opacities in a multifocal, bilateral peripheral, or lower zone distribution, whereas atypical CXR features comprised cavitation and pleural effusion. Conclusion: Typical findings of COVID-19 infection in chest computed tomography studies can also be seen in CXR. The presence of atypical features associated with worse disease outcome. Recognition of these features on CXR will improve the accuracy and speed of diagnosing COVID-19 patients.

Abnormal behaviors of tumors pose a risk to human survival. Thus, the detection of cancers at their initial stage is beneficial for patients and lowers the mortality rate. However, this can be difficult due to various factors related to imaging modalities, such as complex background, low contrast, brightness issues, poorly defined borders and the shape of the affected area. Recently, computer-aided diagnosis (CAD) models have been used to accurately diagnose tumors in different parts of the human body, especially breast, brain, lung, liver, skin and colon cancers. These cancers are diagnosed using various modalities, including computed tomography (CT), magnetic resonance imaging (MRI), colonoscopy, mammography, dermoscopy and histopathology. The aim of this review was to investigate existing approaches for the diagnosis of breast, brain, lung, liver, skin and colon tumors. The review focuses on decision-making systems, including handcrafted features and deep learning architectures for tumor detection.

Background: The automatic segmentation of brain tumour from MRI medical images is mainly covered in this review. Recently, state-of-the-art performance is provided by deep learning- based approaches in the field of image classification, segmentation, object detection, and tracking tasks. Introduction: The core feature deep learning approach is the hierarchical representation of features from images, thus avoiding domain-specific handcrafted features. Methods: In this review paper, we have dealt with a review of Deep Learning Architecture and Methods for MRI Brain Tumour Segmentation. First, we have discussed the basic architecture and approaches for deep learning methods. Secondly, we have discussed the literature survey of MRI brain tumour segmentation using deep learning methods and its multimodality fusion. Then, the advantages and disadvantages of each method are analyzed and finally, it is concluded with a discussion on the merits and challenges of deep learning techniques. Results: The review of brain tumour identification using deep learning. Conclusion: Techniques may help the researchers to have a better focus on it.

Background: The positive correlation between changes in the morphology of masseter and temporal muscles and some disorders, inclines diagnosticians to search for an effective method of assessing muscle thickness and elasticity. Ultrasound imaging, as a relatively simple and cheap method, seems to be a useful diagnostic tool. Objective: The aim of this study was to present the existing ultrasound imaging methods in the assessment of the elasticity and thickness of the masseter and temporal muscles. Methods: The literature review has been done with a focus on the accurate description of the masseter and/or temporal muscle examination by ultrasonography imaging methods. Articles were categorized into two groups. The first group included articles in which muscle thickness was assessed by ultrasound imaging. The second group concerned the elasticity aspect of mentioned muscles. Results: It is difficult to achieve an objective protocol of masseter and temporal thickness assessment by ultrasonography and there is no method that has been fully verified in terms of reliability. The shear-wave sonoelastography revealed higher-level reliability of masseter muscle elasticity than strain sonoelastography. During the shear-wave sonoelastography, the effect of scan plane in relation to masseter muscle pennation and the day-to-day variation were statistically significant. With regard to elasticity of temporal muscle, further research is needed. Conclusion: This review has shown that there is a limited number of methods for masseter and temporal muscle thickness and elasticity measurements by ultrasonography. All procedures (methods) were not fully verified in terms of reliability and agreement. Thus, it is still necessary to develop standardized procures to assess thickness and elasticity of the masseter and temporal muscles with appropriate reliability and accuracy.

Background: Magnetic-Resonance guided Focused Ultrasound (FUS) thalamotomy is a new and less invasive surgical technique for treating Parkinson’s disease (PD). During therapy, the required part of the cerebral (as STN, Internal Globus Pallidus, and Ventral Intermediate Nucleus) is ablated with less possibility of infection and brain hemorrhage as it normally happens in invasive procedures. Introduction: New advancement in the technique enables it for transcranial transportation of US. Nowadays, US coupling with MRI confirms the accurate energy transferring and monitoring. So, MRI guided FUS lesioning is discovered for various psychiatric and brain disorders. Methods: A technical overview of non-invasive MRI-FUS thalamotomy to treat various tremors is described here. Research, review articles, and book chapters are extracted from online resources using related search strings from the year 1994-2020. Results: MRgFUS is concluded a non-invasive, satisfactory, and safe technique to reduce the tremor. Conlusion: MRgFUS is comparatively a new method that is being explored as a non-invasive cerebral ablation to solve the problems of movement disorder.

Background: Breast cancer represents uncontrolled breast cell growth. Breast cancer is the most diagnosed cancer in women worldwide. Early detection of breast cancer improves the chances of survival and increases treatment options. There are various methods for screening breast cancer, such as mammogram, ultrasound, computed tomography and Magnetic Resonance Imaging (MRI). MRI is gaining prominence as an alternative screening tool for early detection and breast cancer diagnosis. Nevertheless, MRI can hardly be examined without the use of a Computer-Aided Diagnosis (CAD) framework, due to the vast amount of data. Objective: This paper aims to cover the approaches used in the CAD system for the detection of breast cancer. Methods: In this paper, the methods used in CAD systems are categories into two classes: the conventional approach and artificial intelligence (AI) approach. Results: The conventional approach covers the basic steps of image processing, such as preprocessing, segmentation, feature extraction and classification. The AI approach covers the various convolutional and deep learning networks used for diagnosis. Conclusion: This review discusses some of the core concepts used in breast cancer and presents a comprehensive review of efforts in the past to address this problem.

Background: Ulcerative colitis (UC) and Crohn's disease (CD) are two varieties of inflammatory bowel disease (IBD). Clinicians need a monitoring technique in the IBD. The disease activity can be assessed with endoscopy, activity indexes, and imaging techniques. Color Doppler US (CDUS) is also a non-invasive, radiation, and contrast material free examination which shows the intramural blood flow. Objective: To evaluate the usefulness of B-mode, CDUS, and a newly developed software Color Quantification (CQ) to determine the activity of the IBD. Methods: The disease activity was assessed by clinical activity indexes. Caecum, terminal ileum, ascending colon, transverse colon, and descending colon were evaluated by B-mode, CDUS, and the CQ. Bowel wall thickness (BWT), loss of bowel stratification, loss of haustration, and the presence of enlarged lymph nodes, mesenteric masses, abscesses, fistula, visual vascular signal patterns of the bowel as “hypo and hyper-flow” and the CQ values were investigated. BWT was compared with laboratory results and clinical activities. Vascular signal patterns and the CQ values were compared with BWT and clinical activity. The diagnostic performances of the CQ were investigated. Results: Fifty-two patients with IBD were evaluated. Patients with increased BWT at the transverse colon had an increased frequency of “hyper-flow” pattern. Clinically active patients had an increased incidence of “hyper-flow” pattern at the terminal ileum, ascending colon, and whole segments. They had increased CQ values at the terminal ileum, ascending colon, and descending colon, and whole segments. A cut-off value for the CQ (24.7%) was obtained at the terminal ileum. In the diagnostic performances of CQ, we observed utilities significantly at the ascending colon, descending colon, terminal ileum, and whole segments. There was a positive correlation between the CQ values and BWT at the caecum, ascending colon, transverse colon, and descending colon. Conclusion: Increased visual vascular signal scores and CQ values might be useful for monitoring the disease activity in patients with IBD.

Background: Due to the significant variances in their shape and size, it is a challenging task to automatically segment gliomas. To improve the performance of glioma segmentation tasks, this paper proposed a multilevel attention pyramid scene parsing network (MLAPSPNet) that aggregates the multiscale context and multilevel features. Methods: First, T1 pre-contrast, T2-weighted fluid-attenuated inversion recovery (FLAIR) and T1 post-contrast sequences of each slice are combined to form the input. Afterwards, image normalization and augmentation techniques are applied to accelerate the training process and avoid overfitting, respectively. Furthermore, the proposed MLAPSPNet that introduces multilevel pyramid pooling modules (PPMs) and attention gates is constructed. Eventually, the proposed network is compared with some existing networks. Results: The dice similarity coefficient (DSC), sensitivity and Jaccard score of the proposed system can reach 0.885, 0.933 and 0.8, respectively. The introduction of multilevel pyramid pooling modules and attention gates can improve the DSC by 0.029 and 0.022, respectively. Moreover, compared with Res-UNet, Dense-UNet, residual channel attention UNet (RCA-UNet), DeepLab V3+ and UNet++, the DSC is improved by 0.032, 0.026, 0.014, 0.041 and 0.011, respectively. Conclusion: The proposed multilevel attention pyramid scene parsing network can achieve stateof- the-art performance, and the introduction of multilevel pyramid pooling modules and attention gates can improve the performance of glioma segmentation tasks.

Background: Peritumoral edema of primary brain tumors is an important cause of morbidity and mortality. The number of studies currently available on the prognostic role of peritumoral brain edema in the posterior fossa is extremely limited. Objective: Based on the known importance of magnetic resonance imaging in diagnosing supratentorial metastases, this study aimed to investigate the effects of peritumoral edema on survival of patients with posterior fossa metastases and the preoperative diagnostic value of MRI. Methods: Edema and mass volumes of 49 patients with posterior fossa metastasis, who underwent surgery during 2012–2016, were measured using magnetic resonance imaging. The edema/mass indices were retrospectively calculated and interpreted by evaluating the demographic, clinical, and survival data. Results: The study consisted of 32 (65.3%) male and 17 (34.7%) female participants, with the mean age ± standard deviation of 47.25±29.25 (17–81) years. Among the 49 patients with posterior fossa metastases, 34 (69.4%) had carcinoma, while 15 (30.6%) had non-carcinoma metastases. The edema/mass indices of patients with carcinoma and non-carcinoma metastases were found to be 14.55±9.64 and 1.34±1.08, respectively, and the difference was statistically significant (p<0.001). The mean survival of patients with carcinoma and non-carcinoma metastases was found to be 642±11.52 days and 726±9.32 days, respectively; however, this difference was not statistically significant (p=0.787). Conclusion: The edema/mass ratio was found to be a significant diagnostic factor for the prediction of posterior fossa metastases. Further detailed studies are warranted to investigate the effect of edema/mass ratio on survival rate.

Background: Elastography (strain or shear-wave) is a method that estimates tissue stiffness. Introduction: The aim of this study is to evaluate the quantitative and semi-quantitative ultrasound elastography methods for the diagnosis of BI-RADS 4a and BI-RADS 3 lesions, which are borderline for biopsy and follow-up. Materials and Methods: 175 consecutive women with 193 ultrasound-visible breast lesions were classified on Conventional B-mode Ultrasonography (CUS) according to the BI-RADS scoring system. Quantitative and semiquantitative values from ultrasound elastography in the form of strain Elastography Ratio (SER), shear Wave Elastography (SWE) and Shear Wave Elastography Ratio (SWER) were obtained. The lesions categorized as BI-RADS 4a and BI-RADS 3 on ultrasound were subsequently re-categorized according to the elastography values. Results: Except for the 13 BI-RADS 2 lesions, the remaining 180 lesions were biopsied. Pathology showed 83 lesions to be benign and 97 to be malignant. The sensitivity and specificity of the CUS were 96.9% and 75.0%, respectively with an accuracy of 86.0%. Cut-off points calculated based on ROC curves were 56.8 kPa for SWE, 3.53 for SWER and 3.81 for SER. When we downgraded BIRADS 4a lesions based on elastography results, the specificity (CUS+SER 96.9%, CUS+SWE 91.7%, and CUS+SWER 90.6%) and the accuracy (CUS+SER 95.3%, CUS+SWE 92.7%, and CUS+SWER 92.2%) were shown to be better than CUS. When we upgraded BI-RADS 3 lesions based on elastography results, the sensitivity of combined sets of SWE (99,0%) and SWER (100,0%) was better than CUS. Conclusion: The rate of false-negative biopsies can be decreased with the combined use of elastography and ultrasonography.

Background: COVID-19 has emerged recently and has become a global concern. Computed tomography (CT) plays a vital role in the diagnosis. Objectives: To characterize the pulmonary CT findings and distributions of COVID-19 infection in regard to different age groups. Methods: Chest CT scan of 104 symptomatic patients with COVID-19 infection from 7 Iraqi isolation centers were retrospectively analyzed between March 10th to April 5th, 2020. Patients were sub-classified according to their ages into three groups (young adult:20-39 years, middle age:40-59 years, and old age:60-90 years). Results: The most common findings were ground-glass opacities (GGO) (92.3%, followed by consolidation (27.9%), bronchovascular thickening (15.4%), and crazy-paving (12.5%). Less commonly, there were tree-in-bud (6.7%), pulmonary nodules (5.8%), bronchiectasis (3.8%), pleural effusion (1.9%), and cavitation (1%). There were no hallo signs, reversed hallo signs, and mediastinal lymphadenopathy. Pulmonary changes were unilateral in 16.7% and bilateral in 83.3%, central in 14.6%, peripheral in 57.3%, and diffuse (central and peripheral) in 28.1%. Most cases showed multi- lobar changes (70.8%), while the lower lobe was more commonly involved (17.7%) than the middle lobe/lingula (8.3%) and upper lobe (3.1%). In unilateral involvement, changes were more on the right (68.8%) than the left (31.2%) side. Compared with middle and old age groups, young adult patients showed significantly lesser frequency of consolidation (17% vs. 13.3% and 37%), diffuse changes 28.1% (14.2% vs. 35.3% and 40.5%), bilateral disease (71.4% vs. 94.1% and 85.2%), and multi-lobar involvement (51.4% vs. 82.4% and 81.4%) respectively. Conclusion: Bilateral and peripheral GGO were the most frequent findings with the right and lower lobar predilection. The pattern and the distribution of CT changes seem to be age-specific.

Background: Infective endocarditis (IE) is an infection of the heart’s endocardial surface. In recent years, nuclear imaging methods have gained importance in the diagnosis of IE. The present study aims to investigate the imaging potential of ^99mTc-labeled vancomycin (^99mTc-Vancomycin) as a new agent that would enable the diagnosis of IE in its early stages when it is difficult to diagnose or has small vegetation in the experimental rat model. Methods:^99mTc-Vancomycin scintigraphy was evaluated for its accumulation in IE with Staphylococcus aureus performed in an experimental rat model. Serial planar scintigraphic and biodistribution analysis of infected vegetations are compared to rats with sterile vegetations. The heart was identified as an infected organ, the liver was identified as a non-infected organ and the heart/liver uptake ratio (T / NT ratio) was compared between infective endocarditis and sterile endocarditis groups. Results: Planar scintigrams (in vivo measurements) showed more uptake in the heart of rats in the infective endocarditis group compared to the uptake in the heart of rats in the sterile endocarditis group, but this difference was not statistically significant (p>0.05). From the ex vivo measurements, the ^99mTc-Vancomycin heart uptake increased significantly (p = 0.016), liver uptake was significantly decreased (p = 0.045) and the T/NT ratio was significantly higher (p = 0.014) in the infective endocarditis group compared to the sterile endocarditis group. Conclusion: In this experimental study, ^99mTc-Vancomycin scintigraphy ensured the detection of ex vivo infected tissue in a rat model of IE. In addition, the absence of significant ^99mTc-Vancomycin uptake in the sterile endocarditis group indicates that this agent targeted the infected tissue instead of the sterile inflammatory tissue. Finally, this agent should also be evaluated with animal- specific imaging devices.

Background: Ovarian granulosa cell tumors that originate from the sex cord-stromal cells represent 2% to 5% of all ovarian cancers. These tumors constitute two subgroups according to their clinical and histopathological features: juvenile granulosa cell tumors (JGCT) and adult granulosa cell tumors (AGCT). Granulosa cell tumor (GCT) is considered to be a low-grade malignancy with a favorable prognosis. Methods: This case series includes four patients who were admitted to our university hospital and had an MRI examination within 5 years. Results: The histopathological subtype of granulosa tumor was the adult type in 3 patients and juvenile type in 1 patient. Even though it is extremely rare, bone metastases were present in one of our patients. Liver metastases were also detected in one patient. The MRI examination of tumors revealed a heterogeneous solid mass that contained cystic components in 3 patients. In one of our patients, the tumor had a multiseptated cystic feature, and all of the tumors were ovoid or round with smooth margins. T1 signal hyperintensity, not suppressed on fat saturation sequences, was observed in 3 patients, which represents its hemorrhagic content. Conclusion: Even though granulosa cell tumor shows a wide spectrum in terms of tumor appearance, some common findings have been shown and especially a hemorrhagic content could be a clue for us. The tumor is known to have a good prognosis, but it may have an unpredictable clinical course, so close follow-up is greatly important.

Introduction: Epithelioid sarcoma (ES) is a rare histopathological type of soft tissue sarcoma. They are subcutaneous soft tissue masses that tend to arise in extremity sites (the classic type, formerly referred to as distal type) or proximal midline region of the body (the proximal type), such as the perineum, genital tract, and pelvis. The head and neck regions are rarely affected by ES, but the infratemporal fossa (ITF) is extremely rare. ES involving the ITF has not been reported before in literature. In this paper, the imaging features of ES were reviewed in detail, and the anatomical structure and epidemiology of ITF were briefly introduced. Sources: We performed a systematic search from 3 databases, CNKI(China National Knowledge Internet), FMRS(Foreign Medical Literature Retrieval Service, Shenzhen METSTR Technology CO., Led. China), and PubMed, to obtain literature from January 1970 to July 2020. Epithelioid sarcoma, head and neck regions, infratemporal fossa, diagnostic imaging, anatomy, MRI, and CT were used as keywords for advanced retrieval. A study had to be found eligible for inclusion to be closely related to ES and/or ITF. A total of 129 related pieces of literature were retrieved successfully, of which 37 were closely related to this study. The case report in this article is from the Affiliated Hospital of North Sichuan Medical College. The present study was approved by the institutional review board of the Affiliated Hospital of North Sichuan Medical College and a written informed consent for the publication of the case was obtained from the patient. Case Presentation: A 33-year-old man accidentally found a slowly growing, painless mass in the left cheek more than a month ago. On plain computed tomography (CT) scan of the outpatient department, an oval slightly low-density mass with well-defined and uniform boundary in the infratemporal fossa was revealed, and on the contrast-enhanced scan, it was homogeneous and moderately enhanced. Initially, the CT appearance favored benign lesions. However, the possibility of a malignant tumor can not be excluded completely. Finally, the patient was referred to the inpatient department a tumor arose from IF and underwent a selective operation. The tumor was completely removed. Histologic findings were compatible with epithelioid sarcoma. Post-operatively, the patient received 2 cycles of radiotherapy, and there was no evidence of recurrence after 6 months follow- up. Conclusion: The imaging manifestations of ES are various. The anatomic structure of ITF is complex and the pathological types are various. It should be very careful in the qualitative diagnosis of tumors from the ITF, and advanced imaging techniques will be useful in imaging diagnosis.

Background: Birt-Hogg-Dubyndrome (BHDS), an autosomal dominant hereditary condition, occurs due to mutations in the gene encoding folliculin (FLCN) in the short arm of the 17^th chromosome characterized by lung cysts with specific skin findings and renal cell carcinoma. Patients have usually complaints related to dyspnea and chest pain due to pneumothorax but they may be asymptomatic due to wide phenotypic heterogeneity. Herein, we report the imaging findings of a case 32-year-old male with BHDS without any symptom who was diagnosed incidentally by computed tomography (CT) due to organ donation. Case Report: In a 32-year-old male patient evaluated as a potential liver donor, CT was performed for preoperative preparation. The patient's medical history was unremarkable. In the CT examination, multiple air cysts of different sizes in both lungs were observed and also, a 7-cm solid renal mass of the right kidney was observed in the dynamic examination. Due to a large number of lung cysts and the presence of solid renal tumors at a young age, BHDS was considered. The patient underwent partial nephrectomy, and the pathology result was hybrid oncocytic-chromophobe renal cell carcinoma. In the genetic examination, a heterozygous germline mutation was detected in the 11^th exon of the FLCN gene. Conclusion: While potential organ donors are generally healthy and asymptomatic individuals, incidental lesions can be detected in the donor organ or other organs in the examination area during radiological imaging. Although most incidental lesions are benign, important clinical conditions can rarely be observed, as in our case. Familial and syndromic conditions should also be considered for the presence of solid renal masses incidentally detected at a young age. To the best of our knowledge, this is the first reported case of BHDS in English literature who was diagnosed incidentally on computed tomography for being a living liver donor.