Background: Our initial clinical study using simple diffusion kurtosis imaging (SDI), which simultaneously produces a diffusion kurtosis image (DKI) and an apparent diffusion coefficient map, confirmed the usefulness of SDI for tumor diagnosis. However, the obtained DKI had noticeable variability in the mean kurtosis (MK) values, which is inherent to SDI. We aimed to improve this variability in SDI by preprocessing with three different filters (Gaussian [G], median [M], and nonlocal mean) of the diffusion-weighted images used for SDI. Methods: The usefulness of filter parameters for diagnosis was examined in basic and clinical studies involving 13 patients with head and neck tumors. Results: The filter parameters, which did not change the median MK value, but reduced the variability and significantly homogenized the MK values in tumor and normal tissues in both basic and clinical studies, were identified. In the receiver operating characteristic curve analysis for distinguishing tumors from normal tissues using MK values, the area under curve values significantly improved from 0.627 without filters to 0.641 with G (σ = 0.5) and 0.638 with M (radius = 0.5). Conclusions: Thus, image pretreatment with G and M for SDI was shown to be useful for improving tumor diagnosis in clinical practice.
We evaluated the usefulness of simple diffusion kurtosis (SD) imaging, which was developed to generate diffusion kurtosis images simultaneously with an apparent diffusion coefficient (ADC) map for 27 cystic disease lesions in the head and neck region. The mean kurtosis (MK) and ADC values were calculated for the cystic space. The MK values were dentigerous cyst (DC): 0.74, odontogenic keratocyst (OKC): 0.86, ranula (R): 0.13, and mucous cyst (M): 0, and the ADC values were DC: 1364 × 10-6 mm2/s, OKC: 925 × 10-6 mm2/s, R: 2718 × 10-6 mm2/s, and M: 2686 × 10-6 mm2/s. The MK values of DC and OKC were significantly higher than those of R and M, whereas their ADC values were significantly lower. One reason for the characteristic signal values in diffusion-weighted images of DC may be related to content components such as fibrous tissue and exudate cells. When imaging cystic disease in the head and neck region using SD imaging, the maximum b-value setting at the time of imaging should be limited to approximately 1200 s/mm2 for accurate MK value calculation. This study is the first to show that the MK values of DC are characteristically higher than those of other cysts.
Introduction: Head impulse, nystagmus, and test of skew (HINTS) is more accurate for the early diagnosis of occipital fossa stroke than magnetic resonance imaging. However, the head impulse test (HIT) is relatively challenging to perform, as it is subjective. Herein, we developed a prototype video HIT (vHIT) system using an iPhone (Apple, Cupertino, CA, USA) that is compact, easy to operate, and analyzable by our iPhone application. Methods: The iPhone-vHIT and a vHIT using EyeSeeCam (Interacoustics, Eden Prairie, NM, USA) were performed on a healthy man in his 30s and on a patient with vestibular neuritis who visited the Mejiro University Ear Institute Clinic. For the iPhone-vHIT, eye movements were detected by analyzing high-speed videos captured using an iPhone camera, and head movements were followed using an iPhone gyro sensor. An iPhone fixation brace was used to capture the video without any blurring. Results: The iPhone-vHIT system obtained vHIT waveforms similar to those of the EyeSeeCam-vHIT system in the healthy man and the patient with vestibular neuritis. The iPhone-vHIT system effectively detected the reduced vestibulo-ocular reflex gain in patients with vestibular neuritis. The iPhone-vHIT system at 120 frames per second was less sensitive to catch-up saccades than the EyeSeeCam. Conclusion: vHIT systems using a smartphone have been reported but are currently unavailable. At present, the iPhone-vHIT application in this study is the only available smartphone-based vHIT system for screening of peripheral vestibular dysfunction. We believe that the prototype iPhone-vHIT with a high-speed camera will be clinically used to perform the vHIT, even though it only examines the lateral semicircular canal.
Increased heart dose during postoperative radiotherapy (RT) for left-sided breast cancer (BC) can cause cardiac injury, which can decrease patient survival. The deep inspiration breath-hold technique (DIBH) is becoming increasingly common for reducing the mean heart dose (MHD) in patients with left-sided BC. However, treatment planning and DIBH for RT are laborious, time-consuming and costly for patients and RT staff. In addition, the proportion of patients with left BC with low MHD is considerably higher among Asian women, mainly due to their smaller breast volume compared with that in Western countries. The present study aimed to determine the optimal machine learning (ML) model for predicting the MHD after RT to pre-select patients with low MHD who will not require DIBH prior to RT planning. In total, 562 patients with BC who received postoperative RT were randomly divided into the trainval (n=449) and external (n=113) test datasets for ML using Python (version 3.8). Imbalanced data were corrected using synthetic minority oversampling with Gaussian noise. Specifically, right-left, tumor site, chest wall thickness, irradiation method, body mass index and separation were the six explanatory variables used for ML, with four supervised ML algorithms used. Using the optimal value of hyperparameter tuning with root mean squared error (RMSE) as an indicator for the internal test data, the model yielding the best F2 score evaluation was selected for final validation using the external test data. The predictive ability of MHD for true MHD after RT was the highest among all algorithms for the deep neural network, with a RMSE of 77.4, F2 score of 0.80 and area under the curve-receiver operating characteristic of 0.88, for a cut-off value of 300 cGy. The present study suggested that ML can be used to pre-select female Asian patients with low MHD who do not require DIBH for the postoperative RT of BC.
Deep inspiration breath-hold (DIBH) is an excellent technique to reduce the incidental radiation received by the heart during radiotherapy in patients with breast cancer. However, DIBH is costly and time-consuming for patients and radiotherapy staff. In Asian countries, the use of DIBH is restricted due to the limited number of patients with a high mean heart dose (MHD) and the shortage of radiotherapy personnel and equipment compared to that in the USA. This study aimed to develop, evaluate, and compare the performance of ten machine learning algorithms for predicting MHD using a patient's body mass index and single-slice CT parameters to identify patients who may not require DIBH. Machine learning models were built and tested using a dataset containing 207 patients with left-sided breast cancer who were treated with field-in-field radiotherapy with free breathing. The average MHD was 251 cGy. Stratified repeated four-fold cross-validation was used to build models using 165 training data. The models were compared internally using their average performance metrics: F2 score, AUC, recall, accuracy, Cohen's kappa, and Matthews correlation coefficient. The final performance evaluation for each model was further externally analyzed using 42 unseen test data. The performance of each model was evaluated as a binary classifier by setting the cut-off value of MHD ≥ 300 cGy. The deep neural network (DNN) achieved the highest F2 score (78.9%). Most models successfully classified all patients with high MHD as true positive. This study indicates that the ten models, especially the DNN, might have the potential to identify patients who may not require DIBH.
Breast Neoplasms , Unilateral Breast Neoplasms , Humans , Female , Unilateral Breast Neoplasms/diagnostic imaging , Unilateral Breast Neoplasms/radiotherapy , Breast Neoplasms/diagnostic imaging , Breast Neoplasms/radiotherapy , Body Mass Index , Machine Learning , Tomography, X-Ray Computed
Diffusion kurtosis (DK) imaging (DKI), a type of restricted diffusion-weighted imaging, has been reported to be useful for tumor diagnoses in clinical studies. We developed a software program to simultaneously create DK images with apparent diffusion coefficient (ADC) maps and conducted an initial clinical study. Multi-shot echo-planar diffusion-weighted images were obtained at b-values of 0, 400, and 800 sec/mm2 for simple DKI, and DK images were created simultaneously with the ADC map. The usefulness of the DK image and ADC map was evaluated using a pixel analysis of all pixels and a median analysis of the pixels of each case. Tumor and normal tissues differed significantly in both pixel and median analyses. In the pixel analysis, the area under the curve was 0.64 for the mean kurtosis (MK) value and 0.77 for the ADC value. In the median analysis, the MK value was 0.74, and the ADC value was 0.75. The MK and ADC values correlated moderately in the pixel analysis and strongly in the median analysis. Our simple DKI system created DK images simultaneously with ADC maps, and the obtained MK and ADC values were useful for differentiating head and neck tumors from normal tissue.
Diffusion Tensor Imaging , Head and Neck Neoplasms , Humans , Diffusion Magnetic Resonance Imaging/methods , Head and Neck Neoplasms/diagnostic imaging , Sensitivity and Specificity
Magnetic resonance imaging (MRI) is superior to computed tomography (CT) in determining changes in tissue structure, such as those observed following inflammation and infection. However, when metal implants or other metal objects are present, MRI exhibits more distortion and artifacts compared with CT, which hinders the accurate measurement of the implants. A limited number of reports have examined whether the novel MRI sequence, multiacquisition variable-resonance image combination selective (MAVRIC SL), can accurately measure metal implants without distortion. Therefore, the present study aimed to demonstrate whether MAVRIC SL could accurately measure metal implants without distortion and whether the area around the metal implants could be well delineated without artifacts. An agar phantom containing a titanium alloy lumbar implant was used for the present study and was imaged using a 3.0 T MRI machine. A total of three imaging sequences, namely MAVRIC SL, CUBE and magnetic image compilation (MAGiC), were applied and the results were compared. Distortion was evaluated by measuring the screw diameter and distance between the screws multiple times in the phase and frequency directions by two different investigators. The artifact region around the implant was examined using a quantitative method following standardization of the phantom signal values. It was revealed that MAVRIC SL was a superior sequence compared with CUBE and MAGiC, as there was significantly less distortion, a lack of bias between the two different investigators and significantly reduced artifact regions. These results suggested the possibility of utilizing MAVRIC SL for follow-up to observe metal implant insertions.
Superior mesenteric venous thrombosis (SMVT), which results from various etiologies, including coagulation disorders, can be diagnosed early using advanced imaging technology. However, few reports have described the nonsurgical treatment of acute peritonitis caused by SMVT. We encountered a young woman whose history included abdominal pain and daily oral contraceptives and who presented with acute peritonitis caused by SMVT. We administered nonsurgical treatment that included thrombolysis and anticoagulation for the peritonitis (without mesenteric ischemia as confirmed by contrast-enhanced computed tomography). In addition, we showed the importance of investigating persistent risk factors for thromboembolism in young patients to determine the duration of anticoagulation.
Anticoagulants/therapeutic use , Fibrinolytic Agents/therapeutic use , Mesenteric Veins/physiopathology , Peritonitis/drug therapy , Peritonitis/etiology , Thrombosis/chemically induced , Thrombosis/drug therapy , Adult , Contraceptives, Oral/adverse effects , Female , Humans , Mesenteric Veins/diagnostic imaging , Tomography, X-Ray Computed , Treatment Outcome
BACKGROUND: Transition to pulmonary arterial hypertension (PAH)-specific drugs is considered in patients with PAH and chronic thromboembolic pulmonary hypertension who do not respond to combination therapy or who experience side effects to the combination drugs. Riociguat directly stimulates soluble guanylate cyclase independently of nitric oxide. Therefore, transition from a phosphodiesterase type 5 inhibitor (PDE5i), which requires nitric oxide to exert its effects, to riociguat might be effective. The length of time of washout periods for transition is important because haemodynamic instability sometimes occurs during these periods or during transition with no washout period. METHOD: We investigated the feasibility of transitioning from a PDE5i to riociguat without washout periods by monitoring haemodynamics under right heart catheterisation in six patients with PAH and one with chronic thromboembolic pulmonary hypertension who had already received dual- or triple-combination therapy. RESULTS: Reasons for transition were headache caused by a PDE5i in three patients, and an inadequate response to combination therapy in four. Transition was successful in all patients, with no haemodynamic instability observed. Pulmonary vascular resistance (from 797 ± 241 to 518 ± 230 dyne/s/cm-5) and systemic blood pressure (from 121 ± 13 to 100 ± 15 mmHg) were significantly reduced immediately after transition. There were no significant differences in the tricuspid regurgitation pressure gradient or systemic blood pressure during the post-transition and follow-up periods. Headaches caused by a PDE5i were diminished after transition to riociguat. CONCLUSIONS: Transition from a PDE5i to riociguat without a washout period is safe. This transition may be a viable option for patients with headaches caused by a PDE5i, or who have an inadequate response to combination therapy that includes a PDE5i.
Cardiac Catheterization , Hemodynamics/drug effects , Phosphodiesterase 5 Inhibitors/administration & dosage , Pulmonary Arterial Hypertension , Pulmonary Embolism , Pyrazoles/administration & dosage , Pyrimidines/administration & dosage , Transitional Care , Adult , Aged , Chronic Disease , Cohort Studies , Female , Humans , Male , Middle Aged , Monitoring, Physiologic , Pilot Projects , Pulmonary Arterial Hypertension/physiopathology , Pulmonary Arterial Hypertension/therapy , Pulmonary Embolism/physiopathology , Pulmonary Embolism/therapy
