Background Gadolinium‐based contrast agents are complex chelates to provide contrast in NRI. However, recent studies have highlighted the deposition of free Gd +3 ion in various tissues. Purpose To evaluate the histopathological and immunohistochemical changes on rat kidney tissue following both macrocyclic (gadoteric acid) and linear (gadodiamide) agents under the hypothesis that gadolinium‐based contrast agents (GBCA) lead to toxic, free Gd +3 accumulation in tissues. Study Type The local Animal Care Committee approved the prospective animal study. Animal Model Thirty‐two healthy Sprague–Dawley male rats were administered 2 mmol/kg gadodiamide and gadoteric acid for the first 4 days for 5 weeks. Group 1 received no drug (control, n = 8) and Group 2 ( n = 8) was administered 0.1 ml/kg saline. Group 3 was administered 0.1 mmol/kg gadodiamide and Group 4 ( n = 8) was administered 2 mmol/kg gadoteric acid. Assessment Biochemical, histopathological, and immunohistochemical changes in testis kidney tissue were evaluated at the end of 10 weeks. Statistical Tests Differences between groups were analyzed using the nonparametric Kruskal–Wallis test followed by one‐way analysis of variance and the Tamhane test, also followed by Turkey's HSD test. Results Gadolinium increased serum urea, Ca +2 , and Caspase‐3 positive tubular cell number. Larger Bowman capsules shrank proximal and distal tubules were revealed in the gadodiamide and gadoteric acid groups compared to the control group ( P < 0.05). Histopathologic examination showed significantly more interstitial fibrosis, amyloid deposits, and vasocongestion in the gadodiamide group than the gadoteric acid and control groups, while the gadoteric acid group demonstrated significantly more leukocytic infiltration with atrophied proximal and distal tubules than the gadodiamide and control groups ( P < 0.05). Data Conclusion GBCA administration causes significant histopathologic changes in kidney tissue. This study advocates additional investigation to assess the in vivo safety of GBCAs. Level of Evidence : 1 Technical Efficacy : Stage 2 J. Magn. Reson. Imaging 2019;49:382–389.
The differentiation of benign and malignant parotid gland tumors is of major significance as it directly affects the treatment process. In addition, it is also a vital task in terms of early and accurate diagnosis of parotid gland tumors and the determination of treatment planning accordingly. As in other diseases, the differentiation of tumor types involves several challenging, time-consuming, and laborious processes. In the study, Magnetic Resonance (MR) images of 114 patients with parotid gland tumors are used for training and testing purposes by Image Fusion (IF). After the Apparent Diffusion Coefficient (ADC), Contrast-enhanced T1-w (T1C-w), and T2-w sequences are cropped, IF (ADC, T1C-w), IF (ADC, T2-w), IF (T1C-w, T2-w), and IF (ADC, T1C-w, T2-w) datasets are obtained for different combinations of these sequences using a two-dimensional Discrete Wavelet Transform (DWT)-based fusion technique. For each of these four datasets, ResNet18, GoogLeNet, and DenseNet-201 architectures are trained separately, and thus, 12 models are obtained in the study. A Graphical User Interface (GUI) application that contains the most successful of these trained architectures for each data is also designed to support the users. The designed GUI application not only allows the fusing of different sequence images but also predicts whether the label of the fused image is benign or malignant. The results show that the DenseNet-201 models for IF (ADC, T1C-w), IF (ADC, T2-w), and IF (ADC, T1C-w, T2-w) are better than the others, with accuracies of 95.45%, 95.96%, and 92.93%, respectively. It is also noted in the study that the most successful model for IF (T1C-w, T2-w) is ResNet18, and its accuracy is equal to 94.95%.
Aims: This study aims to use deep learning (DL) to classify thyroid nodules as benign and malignant with ultrasonography (US). In addition, this study investigates the impact of DL on the diagnostic success of radiologists with different experiences. Material and methods: This study included 576 US images of thyroid nodules. The dataset was divided into 80% training and 20% test sets. Four radiologists with different levels of experience classified the images in the test set as benign-malignant. A DL model was then trained with the train set and predicted benign-malignant for the test set. Then, the output of the DL model for each nodule in the test set was presented to 4 radiologists, who were asked to make a benign-malignant classification again considering these DL results.Results: The accuracy of the DL model was 0.9391. The accuracy for junior resident (JR) 1, JR 2, senior resident (SR), and senior radiologist (Srad) before DL-assisting were 0.7043, 0.7826, 0.8435, and 0.8522 respectively. The accuracy in DL-assisted classifications was 0.9130, 0.8696, 0.9304, and 0.9043 for JR 1, JR2, SR, and Srad, respectively. DL assistance changed the decisions of less experienced radiologists more than more experienced radiologists. Conclusion: The DL model has superior accuracy in classifying thyroid nodules as benign-malignant with US images than radiologists with different levels of experience. Additionally, all radiologists, and most notably less experienced radiology residents, increased their accuracy in DL-assisted predictions.
Objective: Anatomical interactions of vascular and neural structures at cerebellopontine angle (CPA) are considered related to auditory-vestibular symptoms. Magnetic resonance imaging (MRI) has become the preferred method to visualize this complex anatomical region. This study aimed to assess the relation of vascular loops at CPA with clinical symptoms in patients with tinnitus using 3-dimensional (3D) T2-weighted (T2W) MRI.Materials and Methods: The study included 476 patients, grouped as those with and without tinnitus, undergoing MRI for various clinical auditory symptoms. MRI scans were assessed regarding the presence of vascular abnormalities at CPA.Results: For the patients with tinnitus on the left side, the frequencies of Type 1 vascular loop (at the CPA level) (p=0.001) and Type A vascular loop (contact with the vestibulocochlear and facial nerves) (p<0.001) vascular loops were significantly higher. For the patients with tinnitus on the right side, only the frequency of Type A vascular loop was significantly higher (p=0.005). For the patients with bilateral tinnitus, Type 2 vascular loop (proximal to the internal auditory canal [IAC]) on the right side (p=0.035) and Type A vascular loop on the left side (p<0.001) were significantly higher. Conclusion: This study is the largest scale study investigating the tinnitus etiology using 3D T2W MRI. The frequency of vascular loops at the CPA and IAC primarily depends on the diagnostic technique. Our results indicated that vascular causes could be shown more clearly with the use of high-resolution imaging methods. Accordingly, treatment options can be better determined by the clarification of etiology.
To measure and to compare the volume of thalamus using magnetic resonance imaging (MRI) and the anatomical sections.In this study, 13 brain specimens were used. First, the images were taken in 3 mm sections on MRI, the thickness of the thalamus was measured. Subsequently, 4 mm coronal sections were prepared using a microtome. The thalamic volumes calculated from cadaveric specimens were compared with the measurements obtained using MRI.On MRI, the mean thalamic volumes on the right and left hemispheres were found to be 5843.4 ± 361.6 mm3 and 5377.0 ± 666.2 mm3 respectively. The mean volumes of the cadaveric sections were 5610.8 ± 401.3 mm3 on the right side and 5618.5 ± 604.1 mm3 on the left hemisphere. No statistically significant difference was found between the volume calculated from MRI and that obtained from the cadaveric section (p < 0.05).This study shows a correlation between measurement of thalamus volume based on MRI and those calculated from anatomical sections. Our findings support the reliability of DBS procedures using MRI and stereotactic method.
New generation Doppler ultrasonography (DUSG) application effects on cochlea and cochlear nucleus (CN) are unclear. We aimed to investigate the effects of new generation DUSG application at different frequencies in prenatal period on cochlea and CN in rats.Twenty-four pregnant female rats were divided into three groups (n = 8). Group 1 was the control group and was not subjected to any treatment. Group 2 was determined as the USG every day (USGED) treatment group. Group 2 has received DUSG application every day from the 4th to 18th day (20 min/15 per day). Group 3 has received DUSG application as "2 days/one dose as every other day application" (USG2D1) from the 4th to 18th day (20 min/8 every other day). Twenty-four female rats were sacrificed in 21 days. Also, 24 pups were sacrificed after two days. First day after born, the cochlear activities of the right ears of all pups were examined using DPOAEs. Second day, neural tissues from CN were evaluated histopathologically and immunohistochemically.There was no any statistical difference between the groups in respect of histopathologically. USGED group showed mild caspase-3 positive neurons and glial cells. However, there was no significant difference between the USGED and other groups (p>.05). Similarly, the rats applied with USG2D1 had mild caspase-3 expression, but no significant difference between the USG2D1 and other groups (p>.05). Differences in DPOAE amplitudes, and therefore in cochlear activity, between the groups were revealed. The decrease in cochlear activity between the groups involved frequencies at 2, 8, 16, and 32 kHz (p<.05).Multiple administration of new generation DUSG to pregnant rats has not shown harmful effects on the cochlear neural tissue. High frequencies are more sensitive in cochlea to apply DUSG.
