Evaluation of a delineation software for cardiac atlas-based autosegmentation: An example of the use of artificial intelligence in modern radiotherapy

PurposeThe primary objective of this work was to implement and evaluate a cardiac atlas-based autosegmentation technique based on the “Workflow Box” software (Mirada Medical, Oxford UK), in order to delineate cardiac substructures according to European Society of Therapeutic Radiation Oncology (ESTRO) guidelines; review and comparison with other cardiac atlas-based autosegmentation algorithms published to date.Materials and MethodsOf an atlas of data set from 20 breast cancer patients’ CT scans with recontoured cardiac substructures creation according to the ESTRO guidelines. Performance evaluation on a validation data set consisting of 20 others CT scans acquired in the same treatment position: cardiac substructure were automatically contoured by the Mirada system, using the implemented cardiac atlas, and simultaneously manually contoured by a radiation oncologist. The Dice similarity coefficient was used to evaluate the concordance level between the manual and the automatic segmentations.ResultsDice similarity coefficient value was 0.95 for the whole heart and 0.80 for the four cardiac chambers. Average Dice similarity coefficient value for the left ventricle walls was 0.50, ranging between 0.34 for the apical wall and 0.70 for the lateral wall. Compared to manual contours, autosegmented substructure volumes were significantly smaller, with the exception of the left ventricle. Coronary artery segmentation was unsuccessful. Performances were overall similar to other published cardiac atlas-based autosegmentation algorithms.ConclusionThe evaluated cardiac atlas-based autosegmentation technique, using the Mirada software, demonstrated acceptable performance for cardiac cavities delineation. However, algorithm improvement is still needed in order to develop efficient and trusted cardiac autosegmentation working tools for daily practice.     

Une cause réversible de la cardiomyopathie dilatée : l’hypocalcémie

Background

Hypocalcemia is very rare reversible cause of dilated cardiomyopathy (DCMP) witch can concern one or both ventricules. We here presented two cases of DCMP that caused by hypocalcemia and recovered totally after oral calcium and vitamin D supplementation.

Case presentation 1

A 29-year-old Caucasian female was admitted in our hospital due to congestive heart failure with dyspnea (NYHA class IV) and generalized edema for 2 days. She had a history of total thyroidectomy one year a go. She had taken synthyroid as a daily medication associated to calcium supplementation and vitamin D because of hypoparathyroidism. Patient was not compliant to treatment. Trans thoracic echocardiography (TTE) showed a dilated left ventricule (LV) with global hypokinesia with 28% of left ventricule ejection and moderate mitral regurgitation. Laboratory test showed a severe hypocalcemia. After correction of hypocalcemia, there was a clear clinical improvement and four months later a total recovery was found.

Case presentation 2

A 44-year-old Caucasian male was referred to the hospital for rebel congestive heart failure with dyspnea and edema of lower limbs despite optimal treatment. Patient had no medical past history. TEE showed dilated cardiomyopathy with severe alteration of left ventricule systolic function (25%). Biological tests showed a hypocalcemia and primary hypoparathyroidism. An improvement of symptoms after correction of metabolic disorder was found. LV gradually recovered its performance.

Conclusion

Patients outcome in end stage heart failure is different from the classical outcomes in patients with hypocalcemia induced heart disease. DCMP induced by hypocalcemia should be considered in patients with heart failure associated with medical conditions leading to hypocalcemia. It requires a specific treatment.     

Postpartum cardiomyopathy revealed by acute lower limb ischemia

Peripartum cardiomyopathy is an uncommon disease defined as a dilated cardiomyopathy during puerperium, with left ventricular dysfunction (ejection fraction < 45%) without any other etiology. The etiology of this disease remains uncertain and it can be revealed in a variety of ways. Thrombo-embolic complications may be, although infrequently, the initial manifestation of peripartum cardiomyopathy, which is usually an intracardiac thrombosis. Lower extremity embolism is uncommon. The case reported is about a 39-year-old woman, multiparous, who presented, 40 days after delivery, a global heart failure with atrial fibrillation, revealed by left lower extremity thromboembolism. After echocardiographic and etiologic examinations, the diagnosis was established as peripartum cardiomyopathy. It evolved favourably after 2 months of medical treatment: the symptoms and cardiomegaly decreased, left ventricular systolic function was improved.     

Pacemaker longevity. Replacement of the device

Life expectancy of patients implanted with cardiac pacemakers has largely increased, so that generator replacement is becoming an important part of the activity in most of the implanting centers. In more than 70% of the cases, the indication for pacemaker replacement is normal battery depletion. Since the new devices are more and more sophisticated and smaller, longevity optimization becomes a real challenge. The main determinant of pacemaker longevity is the output programmed for the pulse generator. It mainly depends on the output voltage and duration settings. The pacing impedance and the percentage of time with pacing are other major determinants of pacemaker longevity. Each manufacturer provides specific policy but the battery voltage and internal impedance are the more accurate and easy-to-obtain battery depletion parameters. The magnet rate is still frequently used but is less valuable since it can drop abruptly at the end of battery life. The complication rate of pacemaker replacement is three-fold higher than the one of first implant. Infections, skin erosions and lead related complications are not uncommon. The replacement should be systematically preceded by the checking of several points including the patient's pacemaker dependency, the necessity to replace or extract one or several leads, the venous system status, the compatibility between the new generator and the leads and the necessity to upgrade the pacing system or to change the pacemaker pocket.     

Postmarketing surveillance in patients with cardiac pace-makers or automatic implantable defibrillators

This article includes an overview of the actual French control and regulation system of the safety alerts involving pacemakers and implantable cardioverter-defibrillator and an evaluation of the general information and trends about the characteristics of the reported incidents obtained in the last years in that field. The national security agencies have the mission to collect the data on safety and efficacy of medical devices but manufacturers, physicians and patients also have a role to play. The technical appreciation of the necessity of a notification is not easy in some cases but the lack of notification of a severe incident may lead to heavy penal consequences. If doubtful cases, one should keep in mind the spirit of these safety systems: a collective insurance against the risks related to the use of medical devices. In the 10 last years, the annual advisory rate was increased. The pacemakers were recalled more frequently than implantable cardioverter-defibrillators in absolute value but less frequently in relative value (advisories per 100 person-years). This increase may be related to the growing number of device implants and expanding indications for device therapy, to the increasing sophistication of the devices and to the modifications in the regulation aspects of these problems with a closer attention of users and physicians to the several types of malfunctions.     

Patient selection for biventricular pacing

In heart failure patients with a large QRS width, biventricular pacing has been shown to improve the fonctional status as well as hemodynamic parameters. However, there are non-responders despite of wide QRS complexes (between 15 and 35%). Patients selection might not rely only on electrical parameters. From an electrophysiological concept, clinicians moved toward a more electromechanical analysis, by using non-invasive tools such as Tissue Doppler imaging. Thereby, more than the QRS width, identification of intra-left ventricular asynchrony appears to be a crucial criterion for selecting responders to biventricular pacing. From this fact, several studies have demonstrated the efficacy of biventricular pacing to improve heart failure patients with narrow QRS but with intra-left ventricular asynchrony. Another parameter has been thought to be predominant, i.e. the left ventricular pacing site. If the pacing lead is located within a "slow conduction" area (at this time very difficult to identify during the implant procedure), biventricular pacing will generate a new asynchrony counteracting the beneficial expected. Thus, biventricular pacing appears to be more an electromechanical concept than exclusively electrical for selecting responders. Still, the optimal location of the left ventricular pacing lead remains to be determined.