Verifying Efficacy of Self-Inhalation Training for Velopharyngeal Dysfunction.

Velopharyngeal closure in healthy adults during different tasksObjective: Velopharyngeal dysfunction causes not only resonance problems (so-called "hypernasality") but also dysphagia, particularly in the elderly. In our previous study, we developed a new inhaling training method to objectively improve velopharyngeal function using the measurement of peak inspiratory flow (PIF) rate, which was effective in all patients. In this study, we clarify the degree of velopharyngeal closure to determine the efficacy of our training to improve the closure mechanism. METHODS: Three healthy volunteers performed tasks in a magnetic resonance imaging (MRI) gantry in the supine position. To confirm velopharyngeal function, volunteers were first asked to distinguish the difference in the velum position between the production of a nonnasal (sustained phonation /shi:/) and a nasal (sustained phonation /n:/) sound. They were then asked to inhale forcefully through the mouth from an empty 500-mL plastic bottle. For comparison, volunteers performed exhaling forcefully, then inhaling and exhaling softly, through a straw. Each task was performed for 30 s, and the MRI images were obtained in sagittal sections. RESULTS: Inhaling forcefully from an empty plastic bottle created the strongest velopharyngeal closure between the posterior surface of the velum (soft palate) and the posterior pharyngeal wall in all volunteers. CONCLUSION: The results of our MRI study supported our training method. Using inhalation through a PIF meter or from a plastic bottle to create resistance strengthens particularly the levator veli palatini muscle for velopharyngeal closure, which may be useful in patients with other acquired velopharyngeal dysfunctions including physiological aging. Also, anyone anywhere can train with plastic bottles.

Increased Accumulation of 18F-FDG Incidentally Observed in Hyperacute Cerebral Infarction.

ABSTRACT: A 75-year-old man with lung cancer undertook an 18F-FDG PET/CT for staging. He presented neurological symptoms immediately after the 30-minute scan. An emergent MRI study revealed hyperacute cerebral infarction with occlusion of a left MCA branch. At PET/CT, an increased 18F-FDG uptake was observed in the corresponding areas of infarction. In literature, acceleration of compensatory anaerobic glycolysis has been proposed as 1 of the causes of increased uptake in the penumbra of acute cerebral infarction, and a similar process was hypothesized in this case. In addition, a decreased 18F-FDG uptake in the ipsilateral thalamus was noted on the PET/CT images.

Usefulness of maximum intensity projection images of non-enhanced CT for detection of hyperdense middle cerebral artery sign in acute thromboembolic ischemic stroke.

PURPOSE: To compare the sensitivity of the hyperdense middle cerebral artery (MCA) sign between maximum intensity projection (MIP) and conventional averaged images in patients with acute focal neurological deficits with acute thromboembolic MCA occlusion (MCA occlusion group) and patients with acute focal neurological deficits without MCA occlusion (control group). MATERIALS AND METHODS: Initial computed tomography (CT) scans on admission were reconstructed with 5 mm thickness at every 3 mm interval for averaged and MIP images from 1 mm thickness non-contrast axial source images. Images were obtained from 30 cases each in the MCA occlusion and control groups. The CT values in the region of interests (ROIs) on the affected and unaffected sides of the MCA were compared. To compare CT values among subjects, the CT values were normalized by obtaining a ratio on the affected and unaffected sides, and the normalized CT values were analyzed using the receiver operating characteristic (ROC) curve. RESULTS: The hyperdense MCA sign was visually detected on MIP images in 90% cases and on 5 mm averaged images in only 57% cases in the MCA occlusion group. Based on the ROC analysis of the normalized ratio on the affected and unaffected sides, area under the curve of MIP image and averaged image was 0.941 and 0.655, respectively. On MIP images, the optimal threshold of the ratio on the affected and unaffected sides was 1.152 (sensitivity: 90.0%, and specificity: 93.3%). CONCLUSION: The hyperdense MCA sign sensitivity on 5 mm MIP images was significantly higher than that on conventional 5 mm averaged CT images. This could be useful for the early initiation of proper therapy for patients with acute focal neurological deficits.

Evaluation of ischemic heart disease on a 1.5 Tesla scanner: combined first-pass perfusion and viability study.

PURPOSE: We implemented a fast gradient echo (GRE) sequence with an echo-planar imaging (EPI) read-out (FGRE-ET) to conduct myocardial perfusion studies on a conventional scanner. The accuracy of combined perfusion and viability studies is evaluated in comparison with coronary angiography (CAG). MATERIALS AND METHODS: We enrolled 33 patients suspected of having coronary artery disease in this study. Short-axis perfusion images of the left ventricles were acquired following intravenous bolus injection of gadolinium-DTPA (0.05 mml/kg), both after myocardial loading by dipyridamole (0.56 mg/kg) and at rest. Viability studies were obtained using an inversion-recovery FGRE sequence. Radiologists performed blinded film readings. The findings with perfusion and the viability studies were compared with CAG on a segment-to-segment basis corresponding to the coronary arteries' territories. Stenosis equal to or greater than 75% in diameter was considered significant on CAG. The results were also compared with single photon emission computed tomography (SPECT) in 23 patients. RESULTS: The combination of perfusion and viability studies showed 85.7% sensitivity, 88.9% specificity, and 87.2% accuracy in comparison with CAG. SPECT revealed respective rates of 71.7%, 78.3%, and 73.9% in 23 patients of this group. CONCLUSION: Myocardial perfusion studies using FGRE-ET were feasible and accurate, even on a conventional scanner.

Reduction of ringing artifacts in the arterial phase of gadoxetic acid-enhanced dynamic MR imaging.

PURPOSE: We assessed what MR imaging parameters affected ringing artifacts during the arterial phase of gadoxetic acid-enhanced dynamic magnetic resonance (MR) imaging. MATERIALS AND METHODS: We tested various parameters, including imaging matrices, choice of either sequential or elliptical centric phase-encoding scheme, scanning time, and contrast injection rate using new simulation software on a personal computer and visually evaluated clinical MR images retrospectively using a 4-point scale to assess ringing artifacts. RESULTS: The simulation study revealed that square matrices, short scanning time, slow injection rate, and sequential view ordering effectively reduced ringing artifacts, findings confirmed in clinical practice using gadoxetic acid-enhanced MR imaging. Significantly fewer artifacts resulted using a slow injection rate (P<0.05) and using square matrices in the arterial (P<0.05), portal (P<0.01), and hepatocytic (P<0.05) phases. CONCLUSION: Choice of square matrix, slower injection rate, shorter scanning time, and sequential view ordering could reduce ringing artifacts.

Biexponential apparent diffusion coefficients in prostate cancer.

PURPOSE: The purpose of this study was to investigate the need for biexponential signal decay modeling for prostate cancer diffusion signal decays with b-factor over an extended b-factor range. MATERIALS AND METHODS: Ten healthy volunteers and 12 patients with a bulky prostate cancer underwent line scan diffusion-weighted MR imaging in which b-factors from 0 to 3000 s/mm(2) in 16 steps were sampled. The acquired signal decay curves were fit with both monoexponential and biexponential signal decay functions and a statistical comparison between the two fits was performed. RESULTS: The biexponential model provided a statistically better fit over the monoexponential model on the peripheral zone (PZ), transitional zone (TZ) and prostate cancer. The fast and slow apparent diffusion coefficients (ADCs) in the PZ, TZ and cancer were 2.9+/-0.2, 0.7+/-0.2 x 10(-3) mm(2)/ms (PZ); 2.9+/-0.4, 0.7+/-0.2 x 10(-3) mm(2)/ms (TZ); and 1.7+/-0.4, 0.3+/-0.1 x 10(-3) mm(2)/ms (cancer), respectively. The apparent fractions of the fast diffusion component in the PZ, TZ and cancer were 70+/-10%, 60+/-10% and 50+/-10%, respectively. The fast and slow ADCs of cancer were significantly lower than those of TZ and PZ, and the apparent fraction of the fast diffusion component was significantly smaller in cancer than in PZ. CONCLUSIONS: Biexponential diffusion decay functions are required for prostate cancer diffusion signal decay curves when sampled over an extended b-factor range, providing additional, unique tissue characterization parameters for prostate cancer.