Big mitral annular calcification: a case report of a dynamic liquefaction necrosis as a potential source of embolism.

BACKGROUND: Mitral annular calcification (MAC) is a degenerative, mostly asymptomatic abnormality usually in elderly patients. Caseous MAC (cMAC) is a rare form with central liquefaction necrosis, which typically involves the posterior annulus of the mitral valve and can cause serious sequelae. However, optimal management of patients with cMAC is not clearly defined. CASE SUMMARY: In a 71-year-old female patient, MAC was incidentally detected. Tissue characterization with cardiac magnetic resonance (CMR) revealed a cMAC and a conservative approach was chosen. Six months after cMAC diagnosis, the patient developed an acute hemi-occlusion of a retinal artery with cholesterol embolism. At this time, CMR showed a liquefied cavity of the cMAC. Except for atherosclerotic plaques in the aorta and carotid arteries, further stroke work-up was negative. Therefore, the conservative approach was continued. During follow-up, the liquefied cavity regressed completely after another 6 months and the patient was free from further events (total follow-up 3 years since diagnosis of cMAC). DISCUSSION: A clear diagnosis and quantitative assessment of dynamic processes, such as cMAC, are made possible by performing CMR with multi-parametric tissue characterization. Dynamic changes in cMAC may have serious clinical implications, such as mitral regurgitation or systemic embolization. Among cardiac tumours, thrombus and abscess, cMAC should be included in the differential diagnosis of an intracardiac mass of the posterior mitral annulus in order to avoid further inappropriate diagnostic interventions.

Correction: Frequency of infections in 948 MPN patients: a prospective multicenter patient-reported pilot study.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Quantitative enhancement thresholds and machine learning algorithms for the evaluation of renal lesions using single-phase split-filter dual-energy CT.

PURPOSE: To establish thresholds for contrast enhancement-based attenuation (CM) and iodine concentration (IOD) for the quantitative evaluation of enhancement in renal lesions on single-phase split-filter dual-energy CT (tbDECT) and combine measurements in a machine learning algorithm to potentially improve performance. MATERIAL: 126 patients with incidental renal cysts (both hypo- and hyperdense cysts) or high suspicion for renal cell carcinoma (312 total lesions) undergoing abdominal, portal venous phase tbDECT were initially included in this retrospective study. Gold standard was pathological confirmation or follow-up imaging (MRI or multiphasic CT). CM, IOD, and ROI size were recorded. Thresholds for CM and IOD were identified using Youden-Index of the empirical ROC curves. Decision tree (DTC) and random forest classifier (RFC) were trained. Sensitivities, specificities, and AUCs were compared using McNemar and DeLong test. RESULTS: The final study cohort comprised 40 enhancing and 113 non-enhancing renal lesions. Optimal thresholds for quantitative iodine measurements and contrast enhancement-based attenuation were 1.0 ± 0.0 mg/ml and 23.6 ± 0.3 HU, respectively. Single DECT parameters (IOD, CM) showed similar overall performance with an AUC of 0.894 and 0.858 (p = 0.541) (sensitivity 90 and 80%, specificity 88 and 92%, respectively). While overall performance for the DTC (AUC 0.944) was higher than RFC (AUC 0.886), this difference (p = 0.409) and comparison to CM (p = 0.243) and IOD (p = 0.353) was not statistically significant. CONCLUSIONS: Enhancement in incidental renal lesions on single-phase tbDECT can be classified with up to 87.5% sensitivity and 94.6% specificity. Algorithms combining DECT parameters did not increase overall performance.