A 42-year-old man without past medical history presented to our hospital with temporary right sided hemiparalysis and dysarthria. Brain magnetic resonance imaging (MRI) showed multiple cerebrovascular infarctions (Figure 1). Electrocardiography showed sinus rhythm with frequent premature ventricular contractions (PVCs), but no atrial ventricular block. Echocardiography showed partial dyskinesis at the apical lesion and a significant left ventricular (LV) thrombus (Figure 2). Coronary computed tomography angiography (CTA) showed normal coronary arteries (Figure 3). The thrombus became small 4 weeks after anticoagulation therapy with warfarin, but it remained. Therefore, we could not conduct cardiac tissue biopsy because of the additional stroke risks. Gallium-67 scintigraphy showed no specific lesion (Figure 4). However, cardiac MRI showed multiple focal late gadolinium enhancement (LGE) in left ventricle (Figure 5B) where T2 star weighted image (T2WI) also showed pale high intensity (Figure 5A). It suggested active inflammation. Fasting ¹⁸F-fluorodeoxyglucose positron emission tomography (PET) after carbohydrate restriction showed multiple increased cardiac uptake lesions (Figure 6). However, apical lesions showed low uptake, which suggests scar lesions. CTA showed normal coronary arteries but cardiac MRI and PET showed multiple focal lesions, which suggests perfusion-metabolism mismatch. In these results, we diagnosed him with isolated cardiac sarcoidosis and started treatment with 30 mg/day (0.5 mg/kg/day) of prednisone.1) The cardiac function improved by echocardiography, the number of PVCs became half in 24-hour Holter electrocardiogram, and follow-up PET image showed less cardiac uptake 3 months after treatment.