Unsupervised cycle-consistent network using restricted subspace field map for removing susceptibility artifacts in EPI.

PURPOSE: To design an unsupervised deep neural model for correcting susceptibility artifacts in single-shot Echo Planar Imaging (EPI) and evaluate the model for preclinical and clinical applications. METHODS: This work proposes an unsupervised cycle-consistent model based on the restricted subspace field map to take advantage of both the deep learning (DL) and the reverse polarity-gradient (RPG) method for single-shot EPI. The proposed model consists of three main components: (1) DLRPG neural network (DLRPG-net) to obtain field maps based on a pair of images acquired with reversed phase encoding; (2) spin physical model-based modules to obtain the corrected undistorted images based on the learned field map; and (3) cycle-consistency loss between the input images and back-calculated images from each cycle is explored for network training. In addition, the field maps generated by DLRPG-net belong to a restricted subspace, which is a span of predefined cubic splines to ensure the smoothness of the field maps and avoid blurring in the corrected images. This new method is trained and validated on both preclinical and clinical datasets for diffusion MRI. RESULTS: The proposed network could effectively generate smooth field maps and correct susceptibility artifacts in single-shot EPI. Simulated and in vivo preclinical/clinical experiments demonstrated that our method outperforms the state-of-the-art susceptibility artifact correction methods. Furthermore, the ablation experiments of the cycle-consistent network and the restricted subspace in generating field maps did show the advantages of DLRPG-net. CONCLUSION: The proposed method (DLRPG-net) can effectively correct susceptibility artifacts for preclinical and clinical single-shot EPI sequences.

Hippocampal infarction: redefining transient global amnesia.

BACKGROUND AND AIMS: Transient global amnesia (TGA) is a clinical syndrome characterized by sudden anterograde amnesia not accompanied by other neurological symptoms. There is no consensus on the underlying pathophysiological mechanism. However, diffusion-weighted imaging (DWI) of the magnetic resonance imaging (MRI) has demonstrated hippocampal lesions in as many as 50% of cases. This paper describes a series of patients with TGA and hippocampal lesions. METHODS: This study assessed vascular risk factors in patients older than age 18 admitted to the Hospital Universitario San Ignacio, Bogota, Colombia, from May 2017 to June 2020 with a diagnosis of TGA and evidence of hippocampal ischemic lesion on 3 Tesla brain MRI. RESULTS: The authors identified 36 patients, 72.2% female, with mean age 62 years. Cardiovascular risk factors, most frequently high blood pressure, carotid disease, and dyslipidemia, were present in 75% of these patients. Hippocampal lesions were unilateral in 80% of cases, with median size 2.5 mm, most frequently located at the hippocampal body. Approximately 14% of patients also presented acute ischemic lesions in locations other than the hippocampus. CONCLUSIONS: TGA is a clinical entity previously considered to have undetermined etiology. The present study used brain MRI to identify a group of patients with hippocampal ischemic lesions, finding associated vascular risk factors in a high proportion of them.

Local recurrence of renal cell carcinoma after partial nephrectomy: applicability of the apparent diffusion coefficient of MRI as an imaging marker - a multicentre study.

Purpose: The goal of the study was an assessment of the diagnostic performance of diffusion-weighted images (DWI) and apparent diffusion coefficient (ADC) of magnetic resonance imaging (MRI) in distinguishing local recurrence (LR) of renal cell carcinoma (RCC) from benign conditions after partial nephrectomy. Material and methods: Thirty-nine patients after partial nephrectomy for solid RCC were enrolled in the study. Patients were followed up using MRI, which included DWI sequence (b = 800 s/mm2). All patients with MRI features of LR were included in the main group (n = 14) and patients without such features - into the group of comparison (n = 25). Apparent diffusion coefficient (ADC) values of suspicious lesions were recorded. In all patients with signs of locally recurrent RCC, surgical treatment was performed followed by pathologic analysis. Results: The mean ADC values of recurrent RCC demonstrated significantly higher numbers compared to benign fibrous tissues and were 1.64 ± 0.15 × 10-3 mm2/s vs. 1.02 ± 0.26 × 10-3 mm2/s (p < 0.001). The mean ADC values of RCCs' LR and benign post-op changes in renal scar substantially differed from mean ADC values of healthy kidneys' parenchyma; the latter was 2.58 ± 0.05 × 10-3 mm2/s (p < 0.001). In ROC analysis, the use of ADC with a threshold value of 1.28 × 10-3 mm2/s allowed us to differentiate local recurrence of RCC from benign postoperative changes with 100% sensitivity, 80% specificity, and accuracy: AUC = 0.980 (p < 0.001). Conclusions: The apparent diffusion coefficient of DWI of MRI can be used as a potential imaging marker for the diagnosis of local recurrence of RCC.

Identification of residual-recurrent cholesteatoma in operated ears: diagnostic accuracy of dual-energy CT and MRI.

PURPOSE: The aim of this study was to compare the diagnostic accuracy of magnetic resonance imaging (MRI) and dual-energy computed tomography (DECT) to identify residual-recurrent cholesteatoma using the second-look surgery as the reference standard. METHODS: This prospective, institutional review board-approved study included 19 consecutive patients (11 males and 8 females; mean age of 62.2, range 34-80 years). Since five patients were studied bilaterally, a total of 24 ears were evaluated with DECT and MRI between February 2017 and June 2018. Any abnormal middle ear attenuation on high-resolution CT images (HRCT) or DECT color-coded maps, and any abnormal signal on MRI images was evaluated by four experienced radiologists. Diagnostic accuracy values of HRCT, DECT maps and CT numbers (by using receiver operator curves) and MRI were compared. Interobserver and intraobserver agreement were calculated. RESULTS: Residual-recurrent cholesteatoma was diagnosed at surgery in 16/24 ears (66.6%). MRI and DECT revealed a total of 15/16 and 14/16 cholesteatomas, respectively. The sensitivity, specificity, PPV and NPV and accuracy of MRI and DECT were 93.7, 87.5, 93.7, 87.5, and 91.6% and 87.5, 87.5, 93.3, 87.5 and 87.5%, respectively. CT numbers were significantly different between positive (mean 57.6 HU, range - 65, 112 HU) and negative cases (mean 5.4 HU, range - 100, 66 HU) with p < 0.001. The interobserver and intraobserver agreement were k = 0.87 and k = 0.83, respectively. CONCLUSION: DECT may provide an accurate demonstration of residual-recurrent middle ear cholesteatoma.

Apparent Diffusion Coefficient of the Placenta in Twin versus Singleton Pregnancies.

Previous studies in singleton pregnancies reported conflicting trends in apparent diffusion coefficient (ADC) values with gestational age (GA) and stable relative ADC (rADC; ADC placenta divided by ADC globe) throughout pregnancy. The purpose of our study was to compare the ADC and rADC of placentas of twin and singleton pregnancies. MATERIALS AND METHODS: Fetal MRI of 11 twin and 23 singleton pregnancies were retrospectively analyzed. Each group was further divided by GA (≤24 and >24 weeks). On ADC, 3 regions of interest were selected in the placenta and 1 in the globe. ADC and rADC measurements were compared between different GA and between singleton and twin placentas. RESULTS: No significant difference was shown between ADC and rADC values of singleton and twin placentas as well as between ADC and rADC values of singleton and twin placentas at different GA. No significant difference was shown when accounting for both GA and number of fetuses. CONCLUSION: The diffusion characteristics of twin placentas are similar to those of singleton placentas. ADC and rADC remain stable throughout pregnancy in twin and singleton placentas, reflecting stable extracellular water diffusion, despite changes associated with placental maturation.

Liver Imaging Reporting and Data System on CT and gadoxetic acid-enhanced MRI with diffusion-weighted imaging.

OBJECTIVES: To assess major imaging features of Liver Imaging Reporting and Data System (LI-RADS) on contrast-enhanced CT and gadoxetic acid-enhanced MRI and to estimate whether the combination of signal intensity favouring HCC on hepatobiliary phase (HBP) and diffusion-weighted images (DWI) can act as a major feature in LI-RADS. METHODS: Four hundred twenty one patients with 445 observations were included. Major features of LI-RADS on CT and MRI as well as HBP and DWI features were assessed. Diagnostic performances of LR-5 according to LI-RADS v2014 and modified LI-RADS which incorporate combination of HBP and DWI were assessed. Pairwise comparisons of the receiver operating characteristic (ROC) curves were performed. RESULTS: For HCCs, capsule appearance had the highest rate of discordance between CT and MRI (32.7%), followed by washout appearance (22.2%). Specificity (75%) of LR-5 of LI-RADS v2014 was lower than that (77.1-79.2%) of modified LI-RADS. Area under the ROC curve of modified LI-RADS (0.755-0.775) was not significantly different from that of LI-RADS v 2014 (0.709) (p > 0.05). CONCLUSIONS: There were substantial discordances between CT and MRI for capsule and washout appearances in hepatic observations, and combination of gadoxetic acid-enhanced MRI and DWI might be able to be incorporated as a major feature of LI-RADS. KEY POINTS: • Major imaging features of LI-RADS showed substantial discordances on CT and MRI. • An observation may be categorized differently depending on used imaging exam. • CT and MRI should both be performed for LR-3 and LR-4 observations. • Combination of gadoxetic acid-enhanced MRI and DWI may be a major feature.

Diffusion weighted imaging and time in acute ischemic stroke, is there any relation?

BACKGROUND AND PURPOSE: Diffusion-weighted MRI (DWI) is useful for patient selection during the first 6hours after stroke onset. The main aim of this study was to investigate the relationship between the time from stroke symptom onset and stroke volume assessed using DWI. MATERIALS AND METHODS: We evaluated 203 patients with anterior circulation stroke who were admitted to Montpellier's Stroke Unit and for whom a DWI ASPECT score (DWI-ASPECTS) was obtained during the first 6hours from symptom onset. Patients were classified according to the number of hours after the onset of symptoms that DWI was performed. Two experienced neuroradiologists independently calculated the DWI-ASPECTS, which was classified by the size of the stroke volume in three groups: 0-3, 4-6 and 7-10. RESULTS: No relationship was found between temporal groups and the DWI-ASPECTS. The number of patients who reached each of the 3 classified stroke volumes was not different between the temporal groups. CONCLUSION: There is no correlation in our findings between the time of stroke symptom onset and the DWI-ASPECT score during the first 6hours from stroke onset.

A DWI-based hypoxia model shows robustness in an external prostatectomy cohort.

Introduction: Prostate cancer hypoxia is a negative prognostic biomarker. A promising MRI-based tool to assess hypoxia is the 'Consumption and Supply based Hypoxia' (CSH) model based on diffusion-weighted imaging (DWI). The aim of the study was to validate the association between the CSH hypoxia fraction (HFDWI) with pathological Grade Group (pGG) and pathological T-staging (pTstage) in an external prostatectomy cohort. Methods: Apparent diffusion coefficient (ADC) and fractional blood volume (fBV) maps were assessed from DWI data from 291 prostatectomies and combined by the CSH model. HFDWI was calculated for each lesion after median scaling of ADC and fBV to address differences in acquisition and analysis between centers. The absolute HFDWI values and the associations of HFDWI between pGG < 3 versus ≥ 3, and pTstage = 2 versus = 3 in the Netherlands Cancer Institute (NKI) cohort were compared to the obtained by original cohort (Oslo cohort). Statistical T- and Mann-Whitney tests (p<0.05) were performed. Pearson correlation was determined between HFDWI and individual pGG groups. Results: The HFDWI showed comparable absolute values and similar metric performance as in the original published cohort. Higher HFDWI values were observed for higher pGG (Oslo: 0.27; NKI: 0.24) compared to lower pGG (Oslo: 0.11; NKI: 0.17). Similar results were obtained for pTstage. Furthermore, HFDWI demonstrated a significant positive correlation with pGG groups 1-5 (ρ = 0.41, p<0.001). Conclusion: The CSH model exhibited sufficient robustness in the external cohort, suggesting a plausible reflection of true hypoxia and enabling the use of the HFDWI metric for further research into prostate cancer and hypoxia.

Whole-tumor histogram analysis of multiple non-Gaussian diffusion models at high b values for assessing cervical cancer.

PURPOSE: To assess the diagnostic potential of whole-tumor histogram analysis of multiple non-Gaussian diffusion models for differentiating cervical cancer (CC) aggressive status regarding of pathological types, differentiation degree, stage, and p16 expression. METHODS: Patients were enrolled in this prospective single-center study from March 2022 to July 2023. Diffusion-weighted images (DWI) were obtained including 15 b-values (0 ~ 4000 s/mm2). Diffusion parameters derived from four non-Gaussian diffusion models including continuous-time random-walk (CTRW), diffusion-kurtosis imaging (DKI), fractional order calculus (FROC), and intravoxel incoherent motion (IVIM) were calculated, and their histogram features were analyzed. To select the most significant features and establish predictive models, univariate analysis and multivariate logistic regression were performed. Finally, we evaluated the diagnostic performance of our models by using receiver operating characteristic (ROC) analyses. RESULTS: 89 women (mean age, 55 ± 11 years) with CC were enrolled in our study. The combined model, which incorporated the CTRW, DKI, FROC, and IVIM diffusion models, offered a significantly higher AUC than that from any individual models (0.836 vs. 0.664, 0.642, 0.651, 0.649, respectively; p < 0.05) in distinguishing cervical squamous cell cancer from cervical adenocarcinoma. To distinguish tumor differentiation degree, except the combined model showed a better predictive performance compared to the DKI model (AUC, 0.839 vs. 0.697, respectively; p < 0.05), no significant differences in AUCs were found among other individual models and combined model. To predict the International Federation of Gynecology and Obstetrics (FIGO) stage, only DKI and FROC model were established and there was no significant difference in predictive performance among different models. In terms of predicting p16 expression, the predictive ability of DKI model is significantly lower than that of FROC and combined model (AUC, 0.693 vs. 0.850, 0.859, respectively; p < 0.05). CONCLUSION: Multiple non-Gaussian diffusion models with whole-tumor histogram analysis show great promise to assess the aggressive status of CC.

Noise reduction by multiple path neural network using Attention mechanisms with an emphasis on robustness against Errors: A pilot study on brain Diffusion-Weighted images.

PURPOSE: In deep learning-based noise reduction, larger networks offer advanced and complex functionality by utilizing its greater degree of freedom, but come with increased unpredictability, raising the potential risk of unforeseen errors. Here, we introduce a novel denoising model for diffusion-weighted images that intentionally limits the network output freedom by incorporating multiple pathways with varying degrees of freedom, with the aim of minimizing the chance of unintended alterations to the input. The purpose of this pilot study is to assess the model's ability to perform effective denoising under the constraints. METHODS: Images from 10 healthy volunteers were used. Key innovations in our model development include: (1) neural network architecture that separated the function for calculating the specific output values from the function for adjusting the calculation for each pixel and (2) training that optimised the network based on both image and secondary obtained diffusion tensor. The generated images were compared with the original ones by measuring the deviation from ground truth images (averaged across eight acquisitions). RESULTS: The generated images demonstrated closer alignment with the ground truth images, both visually and statistically (Q < 0.05), compared to the original images. Furthermore, the advantage of the generated images over the original images was also found in the secondary obtained quantitative parameter maps with significance (Q < 0.05). CONCLUSION: The usefulness of the proposed method was suggested because it was successful in improving both the quality of the generated images and accuracy of the major diffusion parameter maps under the given restrictions.

Preoperative prediction of VETC in hepatocellular carcinoma using non-Gaussian diffusion-weighted imaging at high b values: a pilot study.

Background: Vessels encapsulating tumor clusters (VETC) have been considered an important cause of hepatocellular carcinoma (HCC) metastasis. Purpose: To compare the potential of various diffusion parameters derived from the monoexponential model and four non-Gaussian models (DKI, SEM, FROC, and CTRW) in preoperatively predicting the VETC of HCC. Methods: 86 HCC patients (40 VETC-positive and 46 VETC-negative) were prospectively enrolled. Diffusion-weighted images were acquired using six b-values (range from 0 to 3000 s/mm2). Various diffusion parameters derived from diffusion kurtosis (DK), stretched-exponential (SE), fractional-order calculus (FROC), and continuous-time random walk (CTRW) models, together with the conventional apparent diffusion coefficient (ADC) derived from the monoexponential model were calculated. All parameters were compared between VETC-positive and VETC-negative groups using an independent sample t-test or Mann-Whitney U test, and then the parameters with significant differences between the two groups were combined to establish a predictive model by binary logistic regression. Receiver operating characteristic (ROC) analyses were used to assess diagnostic performance. Results: Among all studied diffusion parameters, only DKI_K and CTRW_α significantly differed between groups (P=0.002 and 0.004, respectively). For predicting the presence of VETC in HCC patients, the combination of DKI_K and CTRW_α had the larger area under the ROC curve (AUC) than the two parameters individually (AUC=0.747 vs. 0.678 and 0.672, respectively). Conclusion: DKI_K and CTRW_α outperformed traditional ADC for predicting the VETC of HCC.

Magnetic resonance imaging findings of spontaneous pyomyoma in a premenopausal woman managed with myomectomy: A case report.

BACKGROUND: Acute fibroid complications are rare. However, failure to recognize and treat acute complications expeditiously when they occur can lead to catastrophic, even deadly, complications. Pyomyoma is a rare but potentially fatal condition resulting from infarction and infection of a fibroid through bacterial seeding and direct, hematogenous, or lymphatic dissemination. Even though the diagnosis is established through clinical and laboratory findings, imaging is an important complementary method to support the suspected diagnosis. CASE SUMMARY: Herein, we report a case of a pyomyoma in a nulliparous woman previously diagnosed with uterine leiomyomatosis according to ultrasound findings. The patient had previously attended the emergency room due to hypogastric pain unresponsive to analgesics. After a week of persistent pain, she developed sepsis without any identifiable foci. Magnetic resonance imaging revealed findings compatible with uterine myomatosis with red degeneration, and a possible diagnosis of a pyomyoma was made according to the imaging findings along with the patient's clinical features. We decided to perform myomectomy (which is an infrequently performed surgical treatment due to the procedure's intrinsic implications) due to the patient's desire to preserve fertility. Histopathologic results revealed a uterine leiomyoma with coagulative and liquefactive necrosis, while the tissue culture showed gram-negative cocci bacteria, which were successfully treated using antibiotic therapy. The patient's health status improved after several days. CONCLUSION: The main diagnostic tools to evaluate pyomyomas are the clinical and laboratory findings as well as tissue cultures. Nonetheless, magnetic resonance imaging can help to corroborate these findings as well as to better characterize myomas with its different complications.

Intrahepatic Splenosis: A Rare Case.

BACKGROUND: Splenosis refers to the autotransplantation of splenic tissue in a heterotopic location throughout different anatomic compartments, such as the peritoneal and pelvic cavities and even the thoracic cavity. Intrahepatic splenosis is very rare and usually mistaken for a neoplasm. The lack of typical radiological features makes it difficult to distinguish splenosis from liver tumors. CASE REPORT: A 33-year-old female patient presented with post-traumatic splenectomy and had a history of recurrent surgery afterward. There were no significant findings in the physical examination or lab values. Imaging findings were non-specific, with nodular lesions in the liver and scattered in the abdomen. Due to the patient's history, splenosis was considered in the differential diagnosis, and finally, scintigraphy was performed, which confirmed the diagnosis, so unnecessary surgery was avoided. DISCUSSION: Splenosis is the implantation of splenic tissue after an elective or traumatic splenic rupture. US imaging indicates a hypoechoic to isoechoic mass. Low signal intensity on T1 and iso-to-high signal intensity on T2-weighted images are common MRI findings of splenosis. The arterial phase of spleen implantation is varied. Delayed phase signal intensity is usually less than the liver parenchyma. The spleen has the lowest ADC value and the most restricted diffusion of all the intra-abdominal organs. CONCLUSION: In conclusion, splenosis should be considered in the differential diagnosis of patients with a history of spleen surgery or abdominal trauma. It should correlate with the clinical history.

Diffusion-Weighted Images and Contrast-Enhanced MRI in the Diagnosis of Different Stages of Multiple Sclerosis of the Central Nervous System.

Introduction Multiple sclerosis (MS) is one of the most prevalent disorders of the central nervous system (CNS), and it can be observed in the field of radiological cross-sectional magnetic resonance imaging (MRI). The prevalence of MS in Saudi Arabia has increased as compared to the past few years. MRI is the gold standard non-invasive modality of choice in MS diagnosis according to the National Multiple Sclerosis Society (NMSS), New York City. This study aimed to highlight the significance of using diffusion-weighted images (DWIs) and the use of contrast media in the MS protocol, as well as the importance of identifying the suitable time of imaging after contrast enhancement to detect active lesions. Methods A retrospective cross-sectional study was conducted of 100 MS patients with an age range of 17 to 56 years. The data set included 41 active cases and 59 inactive cases. All patients had an MRI standard protocol of both the brain and spine in addition to DWI sequence and contrast agent (CA) injection, with images taken in early and delayed time. Results Of the patients, 71% were female and 29% were male. Active MS disease was more significant at younger ages than at older ages. Active lesions were significantly enhanced in delayed contrast images and showed high signal intensity in both the DWI and apparent diffusion coefficient (ADC) map, while inactive lesions showed no enhancement after contrast injection and showed an iso-signal intensity in both the DWI and ADC map. Conclusion The use of CA has developed over the years in the diagnosis of MS patients. In this study, the relationship between active lesions, DWI, and delayed contrast enhancement is very strong. In future research, we recommend adding a DWI sequence for the suspected active MS spine lesions in addition to delayed enhancement time in active MS after contrast injection to increase MRI sensitivity toward active MS lesions of the brain and spinal cord as well.

The diagnostic utility of size and apparent diffusion coefficient values for cervical lymph nodes in patients with osteomyelitis of the jaw bone.

PURPOSE: The purpose of this study was to (1) clarify the size and apparent diffusion coefficient (ADC) value of lymph nodes (LN) in each state in their quantitative evaluation diffusion-weighted imaging, and (2) to determine the diagnostic utility of size and ADC values in the quantitative evaluation of LNs using diffusion-weighted imaging. METHODS: This was a retrospective cohort study at our hospital conducted between April 2017 and March 2019. A total of 50 patients (20 men, 30 women) with 118 LNs, aged 34-90 years (mean age 61.18 years), undergoing magnetic resonance imaging examination were included in the study. The predictor variable was disease status. The primary outcome variable was the mean size and ADC values of the LNs. The other variables were age and sex. Data were analyzed using a Kruskal-Wallis test, and hoc Mann-Whitney tests with Bonferroni adjustment and a receiver operating characteristic (ROC) curve. P < 0.05 was considered to indicate statistical significance. RESULTS: We analyzed the records of 50 patients (118 LNs) with and without osteomyelitis. Of these, 21 had acute osteomyelitis, and 16 had chronic osteomyelitis. The size and ADC values of LNs in the osteomyelitis group were significantly greater and higher, respectively, than those in the non-myelitis group (P < 0.01). ROC analysis revealed a cutoff short-axis size of 4.42 and 4.04 mm for lymphadenopathy caused by osteomyelitis, corresponding to levels IB and level II, respectively. Moreover, the ADC cutoff values for the same were 0.85 and 0.86, respectively. CONCLUSION: The results suggest that size and ADC values are useful parameters for the quantitative evaluation of lymphadenopathy caused by osteomyelitis.

Breath-Hold Diving-Related Decompression Sickness with Brain Involvement: From Neuroimaging to Pathophysiology.

Central nervous system involvement related to decompression sickness (DCS) is a very rare complication of breath-hold diving. So far, it has been postulated that repeated dives with short surface intervals represent a key factor in the development of breath-holding-related DCS. We report the case of a breath-hold diver who, after repeated immersion, developed DCS with brain involvement. After treatment in a hyperbaric chamber, there was a clinical improvement in the symptoms. Magnetic resonance imaging of the brain showed hyperintense lesions in long-time repetition sequences (FLAIR, T2WI) in the left frontal and right temporal lobes. Diffusion-weighted imaging (DWI) sequences and the apparent diffusion coefficient (ADC) map were characteristic of vasogenic edema, allowing us to exclude the ischemic nature of the process. These findings, together with the acute clinical presentation, the resolution of lesions in evolutionary radiological controls and the possible involvement of blood-brain barrier/endothelial dysfunction in DCS, could suggest a new form of posterior reversible encephalopathy syndrome (PRES)-like presentation of DCS. This would represent a novel mechanism to explain the pathophysiology of this entity. We conducted a literature review, analyzing the pathophysiological and neuroimaging characteristics of DCS in breath-hold diving based on a case of this rare disease.

Temporal Brain MRI Changes From Extrapontine Myelinolysis to Central Pontine Myelinolysis: A Case Report.

We present a case that was initially misdiagnosed as drug-related extrapyramidal side effect. However, after the suspected causative drugs were withdrawn, the patient's condition did not improve. Neuroimaging revealed osmotic demyelination syndrome with a temporal pattern of change from extrapontine myelinolysis to central pontine myelinolysis. Given the limited literature on this rare condition, further research to support clinical diagnosis and treatment is needed.

Magnetic resonance imaging findings of a myxoid leiomyosarcoma of the uterus: A case report and literature review.

Uterine myxoid leiomyosarcomas (MLMSs) are extremely rare. Here, we report a rare case of uterine MLMS with unique and bizarre magnetic resonance imaging (MRI) findings on diffusion-weighted images (DWIs) and dynamic contrast-enhanced (DCE) MRI scans. A 67-year-old woman presented with a uterine MLMS that had a multilocular cystic mass with a septum and solid components. The tumour demonstrated marked hyperintensity on T2-weighted images in a myxoid stroma with gradual partial contrast enhancement and diffusion restriction, which could be a characteristic feature suggestive of a myxoid malignant smooth muscle tumour of the uterus rather than a uterine leiomyoma with myxoid degeneration.

Abbreviated protocol combining quantitative diffusion-weighted imaging: a new strategy increasing diagnostic accuracy for breast magnetic resonance imaging?

BACKGROUND: To compare the diagnostic accuracy of an abbreviated protocol (AP) with or without quantitative apparent diffusion coefficient (ADC) values on diffusion-weighted imaging (DWI) and a full diagnostic protocol (FDP) in terms of the Breast Imaging Reporting and Data System (BI-RADS) classification of breast magnetic resonance imaging (MRI). METHODS: Our study sample consisted of 436 patients undergoing breast MRI from January to October 2015 in a clinical setting. The three reviews included a pre-contrast and the first single post-contrast T1-weighted (T1W) sequences (AP1), AP1 combined with quantitative DWI (AP2), and the FDP, the AP1 of which were assessed independently by a junior and senior radiologist. Agreement on the evaluation of the BI-RADS classifications (between the junior and senior radiologists, between AP1 and FDP, and between AP2 and FDP) was assessed using the kappa test statistic. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were compared between AP1 and FDP plus between AP2 and FDP. Diagnostic parameters of these reviews were examined using the McNemar test. RESULTS: The study included 436 patients, with 251 breast cancers, 99 benign lesions, and 86 patients with benign or no lesions and followed up for at least 24 months. The agreement of the BI-RADS classifications between the junior and senior radiologists was very good (kappa =0.847). The agreement between AP2 and FDP (kappa =0.931) was higher than the agreement between AP1 and FDP (kappa =0.872) on evaluating the BI-RADS benign and malignant classifications. The sensitivity/specificity/PPV/NPV was 95.6%/83.8%/88.9%/93.4% for AP1, 98.0%/83.8%/89.1%/96.9% for AP2, 98.8%/83.8%/89.2%/98.1% for FDP, respectively. CONCLUSIONS: The addition of quantitative DWI to the abbreviated MRI protocol based on the pre-and first post-contrast sequence improved diagnostic performance for characterizing breast lesions. Quantitative DWI may be a useful adjunct to dynamic contrast enhancement (DCE) of breast MRI.

Diffuse astrocytoma and the diagnostic dilemma of an unusual phenotype: A case report.

Diffuse astrocytoma is an infiltrating type of glioma (World Health Organization grade II), which even with histopathology, is difficult to diagnose. Magnetic resonance imaging (MRI) is the cornerstone for diagnoses and follow-up of brain gliomas. This report describes a case of diffuse astrocytoma in a 48-year-old man who presented with sudden right-sided weakness and repeated convulsive attacks. On brain computed tomography, the case was diagnosed and treated as an acute infarction. Ten days later, the patient returned with a total loss of consciousness. Brain MRI images revealed an irregularly outlined lesion involving the splenium of the corpus callosum that extended into the left periventricular parietal lobe of the brain with cystic foci in the septum pellucidum. Contrast-enhanced and new sequences of MRI was helpful in approach to diagnosis because of its superior tissue characterization. The histopathology results ultimately confirmed the diagnosis of diffuse astrocytoma. The patient died postoperatively.