![]() ![]() Of these, a total of 22 patients were excluded. Only lesion volumes derived from sagittal DWI scans entered further statistical analysis, since some lesions were not detectable on axial DWI.įor comparison with previous studies, time dependency of the detectability of infarctions was analyzed in a subgroup of patients with a t-STDWI ≤ 24h.Ī total of 95 patients fulfilled the inclusion criteria. All image analyses were conducted using the software Analyze 11.0 (AnalyzeDirect, Inc., Overland Park, KS, USA). To determine lesion volumes, lesions were outlined on axial and sagittal DWI by manually adjusting the threshold of a seed growing algorithm. Maximal lesion diameters of consensus lesions in all image planes were measured manually on axial DWI and sagittal DWI. Finally, in case of differing results between the observers, a consensus was reached by joint evaluation and these results were used for further analysis. Images were rated in three steps with a minimum of two weeks between each reading step: First, rating was performed on the axial images only (R_AX), secondly, on the sagittal images only (R_SAG), and lastly, the axial and sagittal images were rated together (R_ax+sag). Two observers (M.H.S and R.R., both radiologists with each over 5 years of experience in stroke imaging) blinded to all patient information independently evaluated the DWI images and corresponding ADC maps in random order for the presence or absence of DWI-lesions on a work-station. We hypothesized that an additional thin-sliced sagittal DWI improves the detectability of brainstem infarctions compared to conventional axial DWI alone. ![]() In our institution, for the suspicion of a brainstem infarction, an additional, thin-sliced EPI-DWI in the sagittal plane is routinely acquired. To overcome this issue, acquisition of additional thin-sliced DWI sequences is recommended in some textbooks, but the usefulness of these recommendations has only been shown for an additional thin-sliced axial and coronal DWI. With the exception of some defined syndromes, diagnosis of brainstem infarctions is limited if based on clinical examination only. Still, in the brainstem, where efferent and afferent white matter fibers as well as nuclei of cranial nerves are so close to each other, these small infarcts may lead to grave symptoms. The signal of small infarcts may be blurred by the low spatial resolution of the conventional DWI. Image quality is limited in the brainstem due to susceptibility artifacts caused by the proximity to the skull base and the mastoid. Size of the lesions and susceptibility artifacts have been identified as confounding factors that attribute to false-negative scans. While some studies reported a high detection rate, other studies found high rates of false-negative DWI results for brainstem infarctions. Especially brainstem infarctions have for long been associated with a higher rate of false-negative findings. Whereas the accuracy of DWI is excellent for larger infarcts, sensitivity is considerably lower in small infarcts. ![]() Owing to its high sensitivity and specificity, diffusion weighted imaging (DWI) has substantially facilitated the diagnosis of brain infarction with single-shot echo planar imaging (EPI)-DWI as the current standard. ![]()
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