BACKGROUND: Noncontrast magnetic resonance T1 mapping reflects a composite of 
both intra- and extracellular signal. We hypothesized that noncontrast T1 
mapping can characterize the myocardium beyond that achieved by the 
well-established late gadolinium enhancement (LGE) technique (which detects 
focal fibrosis) in both hypertrophic (HCM) and dilated (DCM) cardiomyopathy, by 
detecting both diffuse and focal fibrosis.
METHODS AND RESULTS: Subjects underwent Cardiovascular Magnetic Resonance 
imaging at 3T (28 HCM, 18 DCM, and 12 normals). Matching short-axis slices were 
acquired for cine, T1 mapping, and LGE imaging (0.1 mmol/kg). Circumferential 
strain was measured in the midventricular slice, and (31)P magnetic resonance 
spectroscopy was acquired for the septum of the midventricular slice. Mean T1 
relaxation time was increased in HCM and DCM (HCM 1209±28 ms, DCM 1225±42 ms, 
normal 1178±13 ms, P<0.05). There was a weak correlation between mean T1 and LGE 
(r=0.32, P<0.001). T1 values were higher in segments with LGE than in those 
without (HCM with LGE 1228±41 ms versus no LGE 1192±79 ms, P<0.01; DCM with LGE 
1254±73 ms versus no LGE 1217±52 ms, P<0.01). However, in both HCM and DCM, even 
in segments unaffected by LGE, T1 values were significantly higher than normal 
(P<0.01). T1 values correlated with disease severity, being increased as wall 
thickness increased in HCM; conversely, in DCM, T1 values were highest in the 
thinnest myocardial segments. T1 values also correlated significantly with 
circumferential strain (r=0.42, P<0.01). Interestingly, this correlation 
remained statistically significant even for the slices without LGE (r=0.56, 
P=0.04). Finally, there was also a statistically significant negative 
correlation between T1 values and phosphocreatine/adenosine triphosphate ratios 
(r=-0.59, P<0.0001).
CONCLUSIONS: In HCM and DCM, noncontrast T1 mapping detects underlying disease 
processes beyond those assessed by LGE in relatively low-risk individuals.