Cardiac MRI (an approach)

A cardiac MRI can be a more or less frequent examination faced in daily practice also depending on the institution. In general radiological practices and institutions other than cardiac imaging centers, cardiac MRI examinations are not necessarily gladly enlisted into the appointment schedule partly due to their sheer time requirements. Therefore their acquisition protocol is usually tailored to the clinical question.

What is presented below is a ’basic approach' for how to organize findings within a radiological report of a cardiac MRI without claim for completeness. This does not cover the workup of every clinical question and every cardiac problem that might be investigated.

Systematic review

Although the clinical question is paramount, many findings and differential diagnoses can be worked off with a few standardized protocols and help the clinician with the further diagnostic process. Thus a systematic review is essential including morphology, function and tissue characteristics.

Morphology

The morphological assessment includes the following:

• cardiac situs, position, cardiac chambers and connections
• pulmonary artery, ascending aorta as well as pulmonary veins
• left and right ventricular size (end-diastolic diameter)
• atrial size
• valvular heart disease
• foramen ovale, atrial and ventricular septal defects
• other forms of congenital heart disease
• pericardial effusion/pericardial thickening
• cardiac tumors
• adjacent mediastinal and pulmonary structures

Function

A left ventricular functional analysis is part of every cardiac MRI and includes the following:

• contraction pattern: synchrony/dyssynchrony

• left ventricular end-diastolic diameter
• left ventricular end-diastolic volume index (LV EDVI) [mL/m²]
• left ventricular end-systolic volume index (LV ESVI) [mL/m²]
• left ventricular stroke volume index (LV SVI) [mL/m²]
• left ventricular ejection fraction (LV EF) [%]
• left ventricular mass index [g/m²]*
• left ventricular regional wall motion abnormalities
  • hypokinesia, akinesia, dyskinesia
  • localization according to the 17 segment model
  • left ventricular clefts, cardiac recesses

Optional: (e.g. arrhythmogenic right ventricular cardiomyopathy, valvular disease, pericardial disease)

• right ventricular end-diastolic diameter
• right ventricular end-diastolic volume index (RV EDVI) [mL/m²]
• right ventricular end-systolic volume index (RV ESVI) [mL/m²]
• right ventricular stroke volume index (RV SVI) [mL/m²]
• right ventricular ejection fraction (RV EF) [%]
• right ventricular regional wall motion abnormalities
  • right ventricular aneurysm

Cardiac tissue characterization

The extent of the cardiac tissue characterization module will vary with the clinical question and might include an assessment of the following:

• myocardial edema: focal or global
• late gadolinium enhancement:
  • patterns: subendocardial/transmural, mid-myocardial, subepicardial
  • localization according to the 17 segment model
  • pericardial enhancement

Optional:

• cardiac perfusion
  • patterns: subendocardial/transmural
  • localization according to the 17 segment model
  • comparison to regional myocardial edema and myocardial scar tissue
• myocardial mapping:
  • native T1 mapping [ms] and possibly extracellular volume (ECV) [%]
  • T2 mapping [ms]
  • T2* mapping [ms]

Flow measurements

Flow measurements are usually acquired for suspected cardiac shunts and might be acquired in the setting of valvular disease. They might be also acquired in the assessment of hypertrophic cardiomyopathy.

In-plane flow measurements can depict and characterize the direction of flow and shunts.

Through-plane flow measurements are usually conducted in the pulmonary artery and ascending aorta at several locations as well as in the left ventricular outflow tract.

Common pathology

• ischemic heart disease
  • myocardial ischemia
  • myocardial infarction
  • ischemic cardiomyopathy/myocardial scar tissue
• myocardial inflammation
  • myocarditis
  • cardiac sarcoidosis
• cardiomyopathies
  • dilated cardiomyopathy
  • hypertrophic cardiomyopathy
  • left ventricular non-compaction
  • Tako tsubo cardiomyopathy
  • arrhythmogenic right ventricular cardiomyopathy
  • iron overload cardiomyopathy
• cardiac amyloidosis
• valvular heart disease
• congenital heart disease
  • atrial septal defect
  • ventricular septal defect
• ​cardiac tumors

and many more...