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University of Yamanashi Yamanashi 409-3898,
Japan University of Tokyo Tokyo 113-8655, Japan
University of Yamanashi Yamanashi 409-3898, Japan
A 78-year-old woman presented with a 2-month history of rapid progressive dementia with myoclonus. MR imaging was performed at admission to our hospital on a 0.2-T clinical MR unit (Signa Profile; General Electric Yokogawa Medical Systems, Tokyo, Japan). After performing conventional T2- and T1-weighted transverse MR imaging, we performed line scan diffusion-weighted imaging in the axial plane. For line scan diffusion-weighted MR imaging, we used a line scan spin-echo MR imaging sequence with a pulsed-gradient diffusion preparation pulse and two b values (0 and 900 sec/mm2) along three directions (anteroposterior, left–right, and superoinferior). Parameters of the line scan diffusion-weighted MR imaging were TR/TE, 220/123; matrix, 128 x 128; bandwidth, 3.92 kHz; and field of view, 260 x 130 mm. Line scan diffusion-weighted MR images revealed cortical atrophy and bilateral abnormal high signal intensity extending from the temporal lobes to the occipital lobes (Figs. 3A and 3B), indicating development of spongioform degeneration. Fluid-attenuated inversion recovery (FLAIR) and T2-weighted MR imaging showed minimal abnormality of T2 elongation (Figs. 3C and 3D). No abnormal density or abnormal signal intensity was detected on CT or T1-weighted MR imaging. Brain biopsy and prion protein gene analysis led to the final diagnosis of Creutzfeldt-Jakob disease deduced by point mutation at codon 180.
Creutzfeldt-Jakob disease is a rare, progressive, and invariably fatal neurodegenerative disease characterized by specific histopathologic features. Clinically, the disease is characterized by rapidly progressive dementia and development of neurologic symptoms, such as myoclonus or ataxia. Features seen on MR imaging of Creutzfeldt-Jakob disease have been previously reported in the literature [1, 2, 3, 4]. Findings obtained with standard imaging sequences (T1- and T2-weighted MR imaging) have been interpreted as displaying normal results in up to 20% of patients with Creutzfeldt-Jakob disease. FLAIR imaging is more sensitive than standard sequences, and the technique is valuable for detecting subtle changes, particularly in the brainstem and cortex [1].
However, if one wishes to estimate the location of lesions in patients with Creutzfeldt-Jakob disease with FLAIR, obtaining images of sufficient quality often takes several minutes. Because patients with Creutzfeldt-Jakob disease often present with myoclonus and thus cannot remain still for the required length of time, FLAIR images have poor image quality caused by motion artifacts. Therefore, a shorter data acquisition method is desired. Recently, use of diffusion-weighted MR imaging has been reported in patients with Creutzfeldt-Jakob disease [2, 3, 4]. New developments in software and hardware make it possible for diffusion-weighted MR images to be obtained even using an MR imager with low field strength. The MR images appeared to be reliable for use in detecting cortical lesions in patients with Creutzfeldt-Jakob disease.
Diffusion-weighted images usually are not obtained on low-magnetic-field MR imagers. However, if possible, in patients in whom Creutzfeldt-Jakob disease is strongly suspected, diffusion-weighted MR imaging is a valuable addition to standard sequences, even if the examination is performed on an MR imager with a low field strength. Moreover, with the present efforts to reduce overall health care costs, the use of low-field-strength MR imaging units seems to be a cost-effective alternative for evaluating the lesions of Creutzfeldt-Jakob disease.
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