جستجوی مقالات مرتبط با کلیدواژه "magnetic resonance" در نشریات گروه "پزشکی"

Complexity metrics have been suggested to characterize treatment plans based on machine parameters such as multileaf collimator (MLC) position. Several complexity metrics have been proposed and related to the Intensity-modulated radiation therapy (IMRT) quality assurance results. This study aims to evaluate aperture-based complexity metrics on MLC openings used in clinicaland establish a correlation between plan complexity and the gamma passing rate (GPR) for the IMRT plans. We implemented the aperture-based complexity metric on MLC openings of the IMRT treatment plan for breast  and central nervous system (CNS) cases . The modulation complexity score (MCS), the edge area metric (EAM), the converted area metric (CAM), the circumference/area (CPA), and the ratio monitor unit MU/Gy are evaluated in this study. The complexity score was calculated using Matlab. The MatriXX Evolution was used for dose verification. The dose distribution was  analyzed using the OmniPro-I'mRT program  and the gamma index was assessed using two criteria: 3%/3 mm and 3%/2 mm. The correlation between the calculated complexity score and the GPR  is analyzed using SPSS. The complexity score calculated by MCS, EAM, CAM, CPA, and MU/Gy shows breast plan is more complex than the CNS plan. The results of the correlation test of the complexity metric and GPR show that only the EAM metric shows a good correlation with GPR for both cases. EAM strongly correlates with the gamma pass rate. The MCS, CAM, CPA, and MU/Gy have a weak correlation with the GPR.

To explore the efficacy and optimal modality of three-dimensional (3D) MRI sequences in the preoperative detection of neurovascular compressions (NVCs) in patients with trigeminal neuralgia (TN).

Forty-nine cases of typical unilateral TN had undergone 3D time-of-flight magnetic resonance angiography (3D-TOF MRA), 3D fast imaging employing steady-state acquisition (3D-FIESTA), and contrast-enhanced 3D spoiled gradient-recalled sequence (3D-SPGR) on a 3 Tesla MR scanner. Neurovascular relationships (including neurovascular contact and position and the nature of the offending vessels) on MR images were reviewed by a neuroradiologist who was unaware of the clinical findings. Subsequently, microvascular decompression (MVD) surgery was performed on all patients. Comparison was made between the imaging results and surgical findings.

MVD verified NVC in 48 (98%) symptomatic nerves, while 3D-TOF MRA, 3D-FIESTA, and 3D-SPGR revealed NVC in 38 (78%), 48 (98%), and 47 (96%) cases, respectively. Agreement between the position of NVC, as defined by 3D-FIESTA (κ = 0.86) or 3D-SPGR (κ = 0.83) and surgical findings, was excellent. Moreover, excellent agreement was confirmed between the nature of compressing vessels as defined by 3D-FIESTA in combination with 3D-TOF MRA (κ = 0.95) or contrast-enhanced 3D-SPGR in combination with 3D-TOF MRA (κ = 0.92) and surgical findings.

NVCs were visualized with good sensitivity and specificity with 3D MRI sequences in TN. We propose that 3D-FIESTA combined with 3D-TOF MRA is a safe, convenient, and efficacious MRI sequence for revealing NVCs and is crucial for the preoperative diagnosis and surgical planning of MVD.

Anatomic variations of the cystic duct (CD) are commonly encountered. Being aware of these variants will reduce complications subsequent to surgical, endoscopic, or percutaneous procedures. Magnetic resonance cholangiopancreatography (MRCP) is the least invasive and the most reliable modality for biliary anatomy surveys. This study aimed to determine the prevalence of cystic duct variations in the Iranian population. In this retrospective cross-sectional study, MRCP images of 350 patients referred to Shiraz Faraparto Medical Imaging and Interventional Radiology Center from October 2017 to October 2018 were reviewed. The CD course and insertion site to the extrahepatic bile duct (EHBD) was determined and documented in 290 cases. Descriptive statistics and Chi square test were applied for data analysis via SPSS software. About 77% of cases revealed the classic right lateral insertion to the middle third of EHBD. The insertion of CD to the upper third and the right hepatic duct was 10%, and the insertion to the medial aspect of the middle third of EHBD from anterior or posterior was noted to be about 7.6%. From 2.8% of insertions to the lower third, 1% demonstrated parallel course, and finally, 0.3% of cases presented short CD. CD variations are relatively common, and MRCP mapping prior to the hepatobiliary interventions could prevent unexpected consequences.

Magnetic resonance cholangiopancreatography (MRCP) is a noninvasive method to detect pancreaticobiliary strictures. In this study, we aimed to evaluate the diagnostic performance of MRCP and detect sensitive and specific radiologic features in distinguishing malignant and benign pathologies.

In this study, 50 patients with biliary obstruction and a confirmed diagnosis using histopathology were included. The pathologies were evaluated using MRCP which were categorized into malignant and benign strictures. The etiology of strictures was detected using histopathology and endoscopic retrograde cholangiopancreatography. The diagnostic performance of MRCP was calculated using SPSS software. P < 0.05 was considered statistically significant.

Of 50 patients, 23 patients (46%) had malignant strictures based on MRCP and histopathology. The sensitivity and specificity of MRCP to detect malignancy were 95.7% and 96.3%, respectively. The most sensitive MRCP features to detect malignancy were upstream biliary duct dilation, abrupt tapering, and the presence of a solid mass with sensitivity 100%, 95.7%, and 78.2%, respectively. The malignancy rate was significantly higher in the strictures with length >11.5 mm or wall thickness >2.75 mm (P < 0.05).

MRCP is a sensitive method to differentiate malignant lesions from benign pathologies. A long and thick stricture with the presence of a solid mass, upstream biliary duct dilation, and abrupt tapering is highly suggestive of malignancy

Autoimmune pancreatitis as chronic inflammation of the pancreas due to an autoim-mune mechanism is a rare type of pancreatitis. A 14 years old girl presented with mul-tiple episodes of abdominal pain, nausea with elevation of amylase and lipase sus-picions of acute recurrent pancreatitis since 3 years of age. After through evaluation about secondary causes of recurrent and familial pancreatitis finally she responded to corticosteroid treatment. Although very rare but autoimmune processes should be considered in teenagers with recurrent pancreatitis.

The most feared complication of laparoscopic cholecystectomy (LC) is biliary tract injuries (BTI). We conducted a prospective study to evaluate the role of preoperative magnetic resonance cholangiopancreatography (MRCP) in describing the biliary tract anatomy and to investigate its potential benefit to prevent BTI.

From January 2012 to December 2016, 402 patients who underwent LC with preoperative MRCP were prospectively included. Routine intraoperative cholangiography was not performed. Patients’ characteristics, preoperative diagnosis, biliary anatomy, conversion to laparotomy, and the incidence of BTI were analyzed.

Preoperative MRCP was performed prospectively in 402 patients. LC was indicated for cholecystitis and pancreatitis, respectively, in 119 (29.6%) and 53 (13.2%) patients. One hundred and five (26%) patients had anatomical variations of biliary tract. Three BTI (0.75%) occurred with a major BTI (Strasberg E) and two bile leakage from the cystic stump (Strasberg A). For these 3 patients, biliary anatomy was modal on MRCP. No BTI occurred in patients presenting “dangerous” biliary anatomical variations.

MRCP could be a valuable tool to study preoperatively the biliary anatomy and to recognize “dangerous” anatomical variations. Subsequent BTI might be avoided. Further randomized trials should be designed to assess its real value as a routine investigation before LC.

The present study aimed to suggest an unsupervised method for the segmentation of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) in axial magnetic resonance (MR) images of the abdomen.
A self-organizing map (SOM) neural network was designed to segment the adipose tissue from other tissues in the MR images. The segmentation of SAT and VAT was accomplished using a new level set method called distance regularized level set evolution (DRLSE). To evaluate the suggested method, the whole-body abdominal MRI was performed on 23 subjects, and three slices were selected for each case.
The results of the automatic segmentation were compared with those of the manual segmentation and previous artificial intelligent methods. According to the results, there was a significant correlation between the automatic and manual segmentation results of VAT and SAT.
As the findings indicated, the suggested method improved detection of body fat. In this study, a fully automated abdominal adipose tissue segmentation algorithm was suggested, which used the SOM neural network and DRLSE level set algorithm. The proposed methodology was concluded to be accurate and robust with a significant advantage over the manual and previous segmentation methods in terms of speed and accuracy.

The cesarean delivery rate tends to be higher in women with sickle cell anemia (SCA) and sickle cell trait (SCT) for various reasons. However, pelvic contracture, which may lead to cesarean sections, has never before been studied in these groups.
The aim of this study was to investigate magnetic resonance (MR) pelvimetry findings of women with SCA and SCT.
Patients and We studied 66 women who underwent MR pelvimetry between March and June 2015 at our center. Our prospective study included 21 women with SCA, 20 women with SCT, and 25 control women. Sagittal inlet, sagittal mid-pelvis, transverse inlet, transverse mid-pelvis and transverse outlet diameters were measured on MR images. The mean diameters were compared with each other and with the control group
Sagittal inlet and transverse inlet were not significantly different between the groups. Also, mid-pelvic diameters for the sagittal and transvers mid-pelvis were similar between the groups. Even though the transverse outlet seems to be lesser in the SCA group compared with other groups, it was not statistically significant.
Our study demonstrated that the pelvic roofs of women with SCA and SCT are indistinguishable from healthy women. Thereby, maternal pelvic structures that impact delivery types may not be significantly changed in SCA and SCT diseases. We believe that when making decisions about modes of delivery, these results should be taken into consideration.

Cardiac magnetic resonance imaging (cMRI) is a well-established noninvasive imaging modality in clinical cardiology. Its ability to provide tissue characterization make it well suited for the study of patients with cardiac diseases. We describe a multi-modality imaging evaluation of a 45-year-old man who experienced a near drowning event during swimming. We underline the unique capability of tissue characterization provided by cMRI, which allowed detection of subtle, clinically unrecognizable myocardial damage for understanding the causes of sudden cardiac arrest and also showed the small damages caused by cardiopulmonary resuscitation..

Uterine inversion is shortly described as the indentation and depression of the fundic area extending downwards up to the different levels of the birth canal till vaginal opening. Clinical diagnosis of uterine inversion is difficult due to its non-specific symptoms and physical examination. Ultrasonography is the most practical modality for radiological evaluation, but it is inadequate to determine the exact nature of this condition and making the differential diagnosis. In this case, we present the main MRI findings of non-puerperal complete uterine inversion caused by a giant leiomyoma..

Nowadays brain tumors remain as a significant cause of morbidity and mortality and are often treatment refractory. The grading of brain tumor has an important implication in clinical management. Currently, magnetic resonance spectroscopy (MRS) is an important modality in evaluating and grading brain tumors. The aim of this study is evaluation of metabolites in the differentiation of brain tumors and grading of brain gliomas using HMRS (proton magnetic resonance spectroscopy). The studies were performed using single voxel MRS، 3Tesla with pulse of sequence used for MRS was point resolved single volume spectroscopy (PRESS) with repetition time (TR) 1000-6000ms and echo time (TE) 36-136ms and The detected distinguished metabolites was included Choline (Cho), Creatin (Cr), and N-acetyl a aspartate (NAA), 37cases had data which passed quality control. The Patient ages ranged from 7 To 81 years, 17 were male and 20 female. MRS data was processed using SYNGO software to give mean spectra and metabolite concentrations which were compared using min it a band SPSS. To test the primary hypothesis, univariate logistic regression was performed on each individual measured metabolite quantity. Significant differences were found in concentrations of key metabolites and Cho/NAA and Cho/Cr ratios using T-test and significance (P≤0. 05). In the assessment of age rate and tumor grading, the malignancies of brain tumors did not correlate with patients’ ages as well as sexuality. MRS can detect subtle differences between low grade brain tumors in children and should form part of the clinical assessment of these tumors.

The purpose of the present study is to determine the accuracy of magnetic resonance voiding cystourethrography (MRVCUG) for diagnosis of vesicoureteral reflux (VUR) in children and adolescents with recurrent urinary tract infection (UTI). During the cross-sectional study from May 2009 to June 2011, 30 patients'' (60 kidney-ureter units) MRVCUG findings by 1.5 T magnetic resonance imaging (MRI) were compared with voiding cystourethrography (VCUG) findings in patients with urinary tract infection. The sensitivity, specificity, positive and negative predictive values for MRVCUG were calculated. The sensitivity, specificity, positive and negative predictive values and accuracy for MRVCUG for detecting VUR were respectively 92.68% (95% CI: 80.57-97.48%), 68.42% (95% CI: 46.01-84.64%), 86.36% (95% CI:71.95-94.33%), 81.25% (95% CI:53.69-95.02%), and 85% (95% CI: 80.40-89.60%. The level of agreement between MRVCUG and VCUG findings for diagnosis VUR was very good (P < 0.001, according to Cohen’s kappa value = 0.638). Studying correlation of low grade VUR (grade I and II) and high grade VUR (grade III-V) showed a very good agreement between MRVCUG and VCUG findings (P < 0.001, Cohen’s kappa value = 0.754). MRVCUG could accurately reveal the presence and severity of VUR, especially in cases with high-grade (grade III-V) VUR in both children and adolescents.