We prospectively examined 71 consecutive patients who were referred by general practitioners to an ambulatory cardiologic examination with suspicion of myocardial involvement after a viral infection. The patients showed symptoms of fatigue, weakness and/or palpitations or precordial discomfort after respiratory or gastrointestinal tract infections. Inclusion criteria were an infection during the last 12 weeks and ongoing symptoms. A CMR examination was performed. The results of these patients were compared with sex- and age-matched 31 healthy controls. All patients were carefully interviewed and examined by experienced cardiologists. Physical examination, ECG, blood pressure, laboratory testing, and echocardiographic evaluation were performed and a written informed consent was obtained from each subject.

One patient experienced claustrophobia during the CMR examination. In one patient, the image quality of the late enhancement was insufficient. In another, the image quality of the STIR sequence was not readable. One patient developed a contrast allergy after application of gadolinium. All these patients were excluded from analysis. Thus, the final cohort comprised 67 patients.

All images were acquired on a 1.5-T magnetic resonance system (Intera CV 1.5T, Philips, Best, The Netherlands) and specifically designed software (Release 11, Philips). The functional and morphological data were evaluated by the software view forum 6.5 (Philips). Regions of interest were drawn manually. Dedicated five element phase-array cardiac synergy coil was used for signal detection. We used constant level appearance techniques. Constant level appearance is a homogeneity correction applied to compensate for signal inhomogeneity attributable to the surface coils. It is equivalent to a SENSE acquisition with a SENSE factor of one to acquire the sensitivity maps for each synergy coil element (relative to the body coil sensitivity) that can be used to get a perfect uniformity correction. At the beginning of the pilot study, controls were scanned with cardiac and body coils. Signal homogeneity, stability, and robustness were better with the cardiac coil. To evaluate LV function and dimensions, we took 2, 3 and 4-chamber long-axis views and 3-D short axis volume data assessed by steady-state free precession imaging (field of view 350 mm, matrix 256 × 256, echo time 1.6 ms, repetition time 4.0 ms, flip angle 60°, slice thickness 10 mm, no gap). In all patients, phase-contrast velocity images in the aorta ascendens were obtained to calculate stroke volume and to rule out a significant aortic insufficiency (field of view 300 mm, matrix 256 × 256, echo time 3.7 ms, repetitions time 6.1 ms, flip angle 25°, slice thickness 8 mm).

ECG-triggered, T2-weighted, fast-spin-echo triple inversion recovery sequences (STIR) were performed in all patients and controls in a short axis view covering the whole left ventricle as previously described [13]. The relative myocardial signal intensity was calculated by the ratio of myocardial signal intensity and muscle signal intensity [15]. The homogeneity of the signal intensity of the region of interest has been studied intensively at the start of the pilot study in volunteers and patients. A very good robustness of the performed STIR sequence showing a homogeneous signal at different time points in the same volunteers was found.

In addition, in 25 patients and 10 controls, ECG-triggered, T1-weighted, multi slice spin-echo images were obtained in axial orientation (3–4 acquisitions, field of view 370 mm, matrix size 256 × 256, slice thickness 10 mm, no gap, echo time 20 ms, flip angle 90°, relaxation time 480–725 ms) with identical parameters before and in 21 patients and 9 controls after intravenous bolus of 0.1 mmol/kg gadolinium-diethylenetriaminepentaacetate (Gd-DTPA) (Magnevist, Schering AG, Germany) (early phase, 1–2 min after bolus injection) A saturation slice across the atria was positioned to reduce signals from slow-flowing blood into the left ventricle. The signal intensity in the myocardial wall and in the skeletal muscles was measured; 5–10 regions of interest were drawn into the septum, anterior, and lateral wall before and after application of Gd-DTPA. In addition, 5–10 regions of interests were drawn into the skeletal muscles (erector spinae muscle or lattissimus dorsi) with homogenous signal. The relative myocardial signal intensity was calculated by the following formula: intensity after Gd-DTPA minus the intensity before Gd-DTPA divided by the intensity before Gd-DTPA ratio of myocardial signal intensity and muscle signal intensity [15].

Delayed enhancement imaging was obtained 10 min after a second bolus of 0.1 mmol/kg intravenous gadolinium by hand injection. 3D inversion recovery turbo gradient echo sequence (2 acquisitions, field of view 330 mm, matrix size 256 × 256, slice thickness 5 mm, no gap, echo time 1,4 ms, TR shortest, flip angle 15°, an inversion time 230–280 ms) was optimized for each measurement for maximal myocardial signal suppression. 3D volume of the left ventricle was obtained covering the complete left ventricle without gap during two breath holds.

Data are presented as mean and standard deviation for quantitative variables and as absolute and relative frequencies for categorical variables. For the evaluation of diagnostic parameters, such as specificity, STIR was dichotomised at its optimal value. Comparisons of variables between patients and controls were performed by means of Wilcoxon’s rank tests. All tests were two-sided and used a significance level of 0.05 to indicate statistical significance. A percent segmental agreement between STIR values and LGE was obtained in the 23 patients who presented with positive LGE.