جستجوی مقالات مرتبط با کلیدواژه "dwi" در نشریات گروه "پزشکی"

To explore the diffusion characteristics of the hippocampus injury (HI) in children during the complex acute febrile seizure (CAFS) through multiple b value (1000-2000 s/mm2) of diffusion-weighted imaging (DWI).

This prospective observational study enrolled children with HI during CAFS, and nasopharyngeal and sinus disease (NSD). The multiple b value from DWI of the hippocampus were scanned.

A total of 41 children were included, with 21 of them had HI during CAFS, while the other 20 children were NSD. There was significant difference in apparent diffusion coefficient (ADC) values of the left and right hippocampus between children with HI during CAFS and NSD (r < 0.05). The corresponding ADC graphs were relatively clear at b = 1000 s/mm2 and 1200 s/mm2.

Hippocampal DWI scans at b = 1000 s/mm2 and 1200 s/mm2 might be recommended clinical b value point for diffusion characterization of HI.

Juvenile fibroadenoma of the breast is a rare benign tumor, which mostly occur in young women. It is often manifested as a huge tumor with obvious enlargement of the breast, regular shape and clear boundary in the breast. This study reported an 18-year-old female, whose physical examination revealed a tough and mobile mass approximately 1.5 cm in diameter on her right breast, the patient had no clinical symptoms. MRI showed a irregular nodules with radial burrs, equisignal on T1WI, slightly high signal density on T2WI, high signal density on DWI, and heterogeneous signal on apparent diffusion coefficient (ADC) images, Enhanced scan showed margin enhancement, and the time-signal intensity curve (TIC) showed plateau and wash-out types. The mass was surgically excised, and histopathological examination revealed that it was a juvenile fibroadenoma tumor.

One type of stroke is the Transient Ischemic Attack (TIA) which lasts less than twenty-four hours; of all patients, about 10 percent develop a stroke within three months after the first symptoms, and 30 percent develop over five years. Imaging is needed for differential diagnosis of this type of stroke. This study aimed to evaluate the recurrence of ischemic stroke and TIA three months after the first transient ischemic attack based on DWI results.

This cross-sectional study was done on 135 TIA patients referred to Alavi Hospital in Ardabil City. All patients were examined at admission time by DWI imaging and laboratory tests and followed up three months later by phone and hospitalization, and necessary information was collected by a checklist.

The average ABCD2 score in people with and without recurrence was 4.69 and 4.02, respectively. Also, the mean ABCD2 score in individuals with abnormal DWI was significantly higher than in individuals with normal DWI (4.72 vs. 4.04, p=0.001). After the first TIA attack, patients with abnormal DWIs had a significantly higher recurrence of TIA and stroke in the first 90 days.

This study showed that TIA patients with higher ABCD2 scores in the first 24 hours based on DWI are more likely to have a recurrence of TIA or the onset of stroke within 90 days.

 Determine clinical and brain MRI findings in patients with repeated stereotypical TIA.

 Thirty-six patients with symptoms of repeated stereotypical TIA were performed MRI & MRA.

 Twenty patients had infarct that 14 cases had lacunar infarct and 6 cases had large infarct.Of these 20 patients, 12 cases had subcortical infarct and 8 cases had cortical infarct. Also, among 36 patients, 18 cases had artery stenosis. There is a significant relationship between artery stenosis and the presence of infarct.In addition, there was no significant relationship between infarct size and the size of the stenosed arteries.

 Most patients with repeated stereotypical TIA have infarct in DWI and they have a thrombotic cause and antiplatelet drug can be used instead of anticoagulants.

Some brain tumors such as ependymoma and Medulloblastoma have similar MR images which may result to undifferentiated them from each other.

This study aimed to compare the apparent diffusion coefficient (ADC) of two different cerebellar pediatric tumors, including ependymoma and medulloblastoma which have shown similar clinical images in conventional magnetic resonance imaging (MRI) methods.

In this analytical study, thirty six pediatric patients who were suspected to have the mentioned tumors according to their CT image findings were included in this study. The patients were subjected to conventional MRI protocols followed by diffusion weighted imaging (DWI) and ADC values of the tumors were calculated automatically using MRI scanner software.

The mean (± SD) ADC value for ependymoma (1.2± 0.06 ×10-3 mm2/s) was significantly higher than medulloblastoma (0.87 ± 0.02 ×10-3 mm2/s) (p = 0.041). Moreover, the maximum ADC value of ependymoma was considerably different in comparison with medulloblastoma (1.4 ×10-3 mm2/s and 0.96×10-3 mm2/s, respectively; p = 0.035). Furthermore, the minimum ADC value of ependymoma was higher compared to medulloblastoma (1.0 ×10-3 mm2/s and 0.61×10-3 mm2/s, respectively), but there was not significant (p = 0.067).

Evaluation of ADC values for ependymoma and medulloblastoma is a reliable method to differentiate these two malignancies. This is due to different ADC values reflected during the evaluation.

Brain metastases are the most common tumors in the human central nervous system (CNS), with an occurrence 10 times higher than primary brain tumors in adults. A radiologist usually diagnoses these tumors. Typically, magnetic resonance imaging (MRI) has been used to evaluate the status and number of metastases, the design of surgical treatment or radiotherapy, and the response to treatment. This study aimed to consider the origin of metastatic tumors of the brain using diffusion-weighted imaging sequence.

In this study, 95 lesions observed in 51 patients with different types of brain metastasis who analyzed with standard brain MRI protocols such as T2-weighted fast spin-echo in sagittal, coronal and axial planes and T1-weighted spin-echo sequences before and after injection of contrast enhancement and diffusion-weighted imaging. The diffusion-weighted imaging included an echo-planar spin-echo sequence with two b values (0,1000 s/mm) and calculated apparent diffusion coefficient (ADC) maps. We measured the ADC-value on normalized ADC maps and compared them with different methods. ANOVA was used to compare ADC among all groups as well as T-test for every two groups.

The results showed that patients with lung cancer (squamous cell carcinoma, SCC) had the lowest mean ADC (658.70*10-3 mm2/s) and breast cancer patients with the highest mean ADC(935.52*10-3 mm2/s). This study demonstrated that most Brain metastases had low and intermediate ADC values. The analysis showed no significant difference among all groups. However, ADC values in breast cancer and kidney and lung (adenocarcinoma) were statistically higher in comparison to other groups. There were no critical discrepancies between ADC values in brain metastases from Breast cancer and lung cancer (adenocarcinoma) and kidney.

It seems that evaluating the origin of the brain metastatic tumors by using diffusion imaging (DWI) parameters could be helpful to prevent invasive methods like biopsies in some situations. Although it needs more studies to achieve this purpose.

        Regarding mediastinal N-staging in lung cancer patients, computed tomography (CT), magnetic resonance imaging (MRI), and integrated 18Fluorine-fluorodeoxyglucose-positron emission tomography/CT (18F-FDG-PET/CT) are the most widespread imaging methodologies in clinical routine. In order to further extract information from non-invasive staging, we evaluated the use of 18F-FDG-PET/CT and dynamic contrast enhanced (DCE) and diffusion-weighted imaging (DWI) MRI using histopathology as the diagnostic gold standard. Patients and A total number of 50 patients had undergone MRI of the chest within two weeks prior to surgery for histopathological proof. DCE-MRI was evaluated on the basis of region of interest (ROI)-based signal intensity/time (SI/T) curves in the respective mediastinal lymph nodes (LNs). In total, 28 LNs could be allocated to the corresponding histopathological findings, as well as to corresponding findings in 18F-FDG-PET/CT. Malignant LNs presented with significantly higher FDG uptake in PET. Significant differences between malignant and benign LNs were found for DCE-MRI regarding the parameters MaxE, 4-minutes value, SE, EP and EP/MaxE. In DWI-MRI, malignant LNs presented with significantly lower signal intensity compared to benign LNs (p < 0.01). An apparent diffusion coefficient (ADC) threshold of 1528 mm2/s was found to exclude malignancy for LNs that are above the threshold. 18F-FDG-PET in addition with MRI that includes DWI might improve mediastinal N-staging, which is of interest in cases of FDG-equivocal LNs. An ADC threshold of 1528 mm2/s might potentially help to further classify LNs with indefinite PET-findings. DCE-MRI of mediastinal LNs seems not yet to be approved for clinical routine.

OBJECTIVESIn this work, we aimed to propose an automatic classification scheme based on the parameters derived from apparent diffusion coefficient (ADC)-maps for discriminating benign and malignant parotid tumors.
METHODSMRI was carried out prospectively on 41 patients presented with parotid tumors who underwent surgery and post-surgical histopathological assessment was provided for them (32 benign, 9 malignant). Based on anatomical images, regions of interest (ROIs) were selected on the most solid parts of tumors on ADC-maps. Three quantitative parameters, namely ADC-Mean, ADC-Max and ADC-Mean were calculated. Automatic classification of parotid tumors using ADC parameters was performed and assessed employing two different classifiers, namely, linear discriminant analysis (LDA) and quadratic discriminant analysis (QDA).
RESULTSFollowing statistical analysis, it was indicated that the ADC values in benign tumors are significantly higher than malignant tumors. ADC-Mean, and -Max presented statistically significant differences among benign and malignant parotid tumors (pCONCLUSIONSADC-Max is a potential biomarker for discriminating benign and malignant parotid tumors. Using ADC-Max and LDA, a simple and clinically-feasible classifier is proposed.

Salivary gland tumors form nearly 3% of head and neck tumors. Due to their large histological variety and vicinity to facial nerves, pre-operative diagnosis and differentiation of benign and malignant parotid tumors are a major challenge for radiologists. The majority of these tumors are benign; however, sometimes they tend to transform into a malignant form. Functional MRI techniques, namely dynamic contrast enhanced (DCE-) MRI and diffusion-weighted MRI (DWI) can indicate the characteristics of tumor tissue. DCE-MRI analysis is based on the parameters of time intensity curve (TIC) before and after contrast agent injection. This method has the potential to identify the angiogenesis of tumors. DWI analysis is performed according to diffusion of water molecules in a tissue for determination of the cellularity of tumors. According to the literature, these methods cannot be used individually to differentiate benign from malignant salivary gland tumors. An effective approach could be to combine the aforementioned methods to increase the accuracy of discrimination between different tumor types. The main objective of this study is to explore the application of DCE-MRI and DWI for assessment of salivary gland tumor types.