Jihoon Kang

Randomized clinical trial for apogeotropic horizontal canal benign paroxysmal positional vertigo

Objective: To determine the immediate and long-term therapeutic efficacies of Gufoni and head-shaking maneuvers in apogeotropic type of benign paroxysmal positional vertigo involving the horizontal semicircular canal (HC-BPPV), a randomized, prospective, sham-controlled study was conducted. Methods: In 10 nationwide dizziness clinics in Korea, 157 consecutive patients (95 women, age range: 18–89 years, mean age ± SD = 59.9 ± 13.6) with apogeotropic HC-BPPV were randomized to Gufoni (n = 52), head-shaking (n = 54), or sham maneuver (n = 51). For Gufoni maneuver, patients underwent ipsilesional side-lying and upward head-turn for migration of the debris toward the vestibule. Immediate responses were determined within 1 hour after a maximum of 2 trials of each maneuver and in the following day. The patients also had weekly follow-ups for 1 month after the initial maneuver. Results: After a maximum of 2 maneuvers on the initial visit day, Gufoni (38/52, 73.1%) and head-shaking (33/53, 62.3%) maneuvers showed better responses than the sham maneuver (17/49, 34.7%). The cumulative therapeutic effects were also better with Gufoni (p < 0.001) and head-shaking (p = 0.026) maneuvers compared with the sham maneuver. However, therapeutic efficacies did not differ between the Gufoni and head-shaking groups in terms of both immediate (p = 0.129) and long-term (p = 0.239) outcomes. Conclusion: Using a prospective randomized trial, we demonstrated that the Gufoni and head-shaking maneuvers are effective in treating apogeotropic HC-BPPV. Classification of evidence: This study provides Class II evidence that Gufoni and head-shaking maneuvers are effective in treating apogeotropic horizontal BPPV up to 1 month after initial treatment. Clinical trial registration: NCT00810641.

Intracerebral hemorrhages in CADASIL

Intracerebral hemorrhage (ICH) has been described only sporadically for patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). However, cerebral microbleeds (CMBs) were found in 31% to 69% of the patients with CADASIL, and this predicted an increased risk of ICH. In this study, the authors found that 25% of the symptomatic patients with CADASIL had ICHs, and their development was closely related to the number of CMBs.

A prototype MR insertable brain PET using tileable GAPD arrays

The aim of this study is to develop a MR compatible PET that is insertable to MRI and allows simultaneous PET and MR imaging of human brain. The brain PET having 72 detector modules arranged in a ring of 330 mm diameter was constructed and mounted in a 3-T MRI. Each PET module composed of 4 × 4 matrix of 3 mm × 3 mm × 20 mm LYSO crystals coupled to a tileable 4 × 4 array Geiger-mode avalanche photodiode (GAPD) and designed to locate between RF and gradient coils. GAPD output charge signals were transferred to preamplifiers using flat cable of 3 m long, and then sent to position decoder circuit (PDC) identifying digital address and generating an analog pulse of the one interacted channel from preamplifier signals. The PDC outputs were fed into FPGA-embedded DAQ boards. The analog signal was digitized, and arrival time and energy of the signal were calculated and stored. LYSO and GAPD were located inside MR bore and all electronics including preamplifiers were positioned outside MR bore to minimize signal interference between PET and MR. Simultaneous PET/MR images of a hot-rod and Hoffman brain phantom were acquired in a 3-T MRI using the MR compatible PET system. The rods down to a diameter of 3.5 mm were resolved in the hot-rod PET image. Activity distribution patterns between white and gray matter in Hoffman brain phantom were well imaged. No degradation of image quality of the hot-rod and Hoffman brain phantoms on the simultaneously acquired MR images obtained with standard sequences was observed. These results demonstrate that simultaneous acquisition of PET and MR images is feasible using the MR insertable PET developed in this study.

Randomized clinical trial for geotropic horizontal canal benign paroxysmal positional vertigo

Objectives: To determine the immediate and long-term therapeutic efficacies of barbecue rotation and Gufoni maneuvers, a randomized, prospective, and sham-controlled study was conducted in patients with the geotropic type of benign paroxysmal positional vertigo involving the horizontal semicircular canal (HC-BPPV). Methods: In 10 nationwide dizziness clinics in Korea, 170 consecutive patients (107 women, age range 11−97 years, mean age ± SD 61 ± 15 years, median = 61 years) with geotropic HC-BPPV were randomly assigned to barbecue rotation (n = 56), Gufoni (n = 64), or sham maneuver (n = 50). An immediate response was determined within 1 hour after a maximum of 2 trials of each maneuver on the visit day. We also assessed the cumulative results of each maneuver by following up the patients for 1 month. Results: After a maximum of 2 maneuvers on the initial visit day, barbecue rotation (38 of 55 [69.1%]) and Gufoni (39 of 64 [60.9%]) maneuvers showed better responses than the sham maneuver (17 of 48 [35.4%]). The cumulative therapeutic effects were also better with barbecue rotation (p = 0.006) and Gufoni (p = 0.031) maneuvers than with the sham maneuver. However, therapeutic efficacies did not differ between the barbecue rotation and Gufoni groups in terms of both immediate (p = 0.46) and long-term (p = 0.10) outcomes. Conclusion: Using a prospective randomized trial, we demonstrated that barbecue rotation and Gufoni maneuvers are effective in treating geotropic HC-BPPV. Classification of evidence: This study provides Class I evidence that barbecue rotation and Gufoni maneuvers are effective in the treatment of geotropic HC-BPPV.

A feasibility study of photosensor charge signal transmission to preamplifier using long cable for development of hybrid PET-MRI.

PURPOSE A new positron emission tomography (PET) detector signal processing method, the charge signal transmission approach, is proposed for the development of a hybrid PET-magnetic resonance imaging (MRI). A number of experiments were performed to demonstrate that the Geiger-mode avalanche photodiode (GAPD) charge output could be transmitted to a preamplifier using a long cable without degrading the PET signal performance. METHODS A PET module consisted of LYSO and a GAPD with a 4 x 4 array. The GAPD output was transmitted to the preamplifier through flexible flat cables. The effect of the cable length on the PET performance was examined using seven different lengths ranging from 10 to 300 cm outside and inside the 7 T animal MRI. Four parameters (rise time, fall time, amplitude, and area of the preamplifier output) were measured as a function of the cable length using a 10 GS/s oscilloscope and three parameters (photopeak position, energy resolution, and time resolution) were measured using a 100 MS/s DAQ unit. The effect of the cable length on the MR phantom images was investigated. In addition, the effect of the PET module configuration on its temperature stability was assessed by acquiring the energy and time spectra. RESULTS There were no significant changes in the PET module performance as a function of the cable length, both outside and inside MRI. The performance changes in energy information, such as the amplitude, area, photopeak position, and energy resolution, were <3% with cable lengths ranging from 10 to 300 cm and the change in the time resolution was <6%. There were no obvious artifacts or changes in the line profile in the MR phantom images. Moreover, no manifest changes in the photopeak position and coincidence counting rate were observed in the PET modules employing the charge signal transmission approach, whereas considerable degradation of the PET module performance was observed in the voltage signal transmission approach. CONCLUSIONS This study demonstrated that it is feasible to design a hybrid PET-MRI using the charge signal transmission approach, which is expected to have more advantages than other approaches.

Effect of blood pressure on 3-month functional outcome in the subacute stage of ischemic stroke

ABSTRACT Objective: We aimed to study various measures of blood pressure (BP) in the subacute phase of ischemic stroke to determine whether any of them predicted clinical outcome. Methods: In this retrospective observational study, a consecutive series of patients hospitalized for ischemic stroke within 48 hours of onset were enrolled. The subacute stage of stroke was defined as the time period from 72 hours of symptom onset to discharge or transfer. During this period, mean, maximum, maximum − minimum, SD, and coefficient of variation of systolic BP (SBP) and diastolic BP (DBP) were determined. A baseline severity-adjusted analysis was performed using each patient’s 3-month modified Rankin Scale score as the primary outcome. Results: Among a total of 2,271 patients, the median number of BP measurements was 34 per person and the median interval from onset to discharge was 8.7 days. Measures of variability of BP were associated with poor outcome. One SD increase of maximum − minimum (odds ratio [OR], 1.26; 95% confidence interval [CI], 1.12–1.42), SD (OR, 1.20; 95% CI, 1.07–1.34), or coefficient of variation (OR, 1.21; 95% CI, 1.09–1.35) for SBP, but not mean level of SBP (OR, 0.92; 95% CI, 0.79–1.07), was independently associated with poor outcome. Results were similar for DBP. Conclusion: This study shows that variability of BP, but not average BP in the subacute stage of ischemic stroke, is associated with functional outcome at 3 months after stroke onset.

Blood pressure variability and the development of early neurological deterioration following acute ischemic stroke

Objectives: Early neurological deterioration (END) is a common condition associated with poor outcome after acute ischemic stroke. We studied association between blood pressure (BP) variability and development of END. Methods: In this retrospective observational study, we studied a consecutive series of patients hospitalized for acute ischemic stroke within 24 h of onset. The primary outcome of interest was the development of END according to predefined criteria within the first 72 h of stroke onset. During this period, the mean, maximum (max), and minimum (min) values for the SBP and DBP were measured. The following parameters of BP variability were calculated for the SBP and DBP: the difference between the maximum and minimum (max−min), the SD, and the coefficient of variation. Results: Of the 1161 patients enrolled in the study (mean age, 67.5 ± 13.3 years; 59.6% men), 210 (18.1%) developed END. All of the BP variability parameters were linearly associated with END independent of mean BP and potential clinical variables (P values < 0.05 on likelihood ratio tests for trend), except for SBPmax−min. Among the other BP parameters, SBPmean, SBPmax, DBPmax, and DBPmin were independently associated with END. After adjustments for potential confounders, the odds for END increased 14–21% with each increase of one standard deviation in the BP variability parameter. Conclusion: BP variability is independently and linearly associated with the development of neurologic deterioration in acute stage of ischemic stroke.

A small animal PET based on GAPDs and charge signal transmission approach for hybrid PET-MR imaging

Positron emission tomography (PET) employing Geiger-mode avalanche photodiodes (GAPDs) and charge signal transmission approach was developed for small animal imaging. Animal PET contained 16 LYSO and GAPD detector modules that were arranged in a 70 mm diameter ring with an axial field of view of 13 mm. The GAPDs charge output signals were transmitted to a preamplifier located remotely using 300 cm flexible flat cables. The position decoder circuits (PDCs) were used to multiplex the PET signals from 256 to 4 channels. The outputs of the PDCs were digitized and further-processed in the data acquisition unit. The cross-compatibilities of the PET detectors and MRI were assessed outside and inside the MRI. Experimental studies of the developed full ring PET were performed to examine the spatial resolution and sensitivity. Phantom and mouse images were acquired to examine the imaging performance. The mean energy and time resolution of the PET detector were 17.6% and 1.5 ns, respectively. No obvious degradation on PET and MRI was observed during simultaneous PET-MRI data acquisition. The measured spatial resolution and sensitivity at the CFOV were 2.8 mm and 0.7%, respectively. In addition, a 3 mm diameter line source was clearly resolved in the hot-sphere phantom images. The reconstructed transaxial PET images of the mouse brain and tumor displaying the glucose metabolism patterns were imaged well. These results demonstrate GAPD and the charge signal transmission approach can allow the development of high performance small animal PET with improved MR compatibility.

Micrographia after thalamo-mesencephalic infarction: Evidence of striatal dopaminergic hypofunction

A patient with left thalamo-mesencephalic infarction presented with micrographia in the right hand as the only motor sign. Brain MRI and99m Tc ethyl cysteinate dimer (ECD) perfusion SPECT revealed ischemic lesions in the left midbrain and the anterior thalamus, but not in the basal ganglia, whereas [123I]-IPT SPECT demonstrated decreased activity of the [123I]-IPT in the left striatum. The patients micrographia may be related to a dysfunctional nigrostriatal dopaminergic system secondary to ischemic damage to the substantia nigra.

Limitation of Brachial-Ankle Pulse Wave Velocity in Assessing the Risk of Stroke: Importance of Instantaneous Blood Pressure

Background and Objective: The carotid-femoral pulse wave velocity is a well-established index of aortic stiffness, and the brachial-ankle pulse wave velocity (baPWV) has recently been developed as a new method for evaluating arterial stiffness. However, whether the baPWV is also useful in evaluating the risk of stroke is currently controversial. Moreover, it is also unknown which types of stroke and neuroradiological findings are associated with increased arterial stiffness. We investigated the association between the baPWV and risk of stroke using a case-control design. Methods: This study enrolled 223 stroke patients (aged 65.6 ± 10.3 years, mean ± SD) and the same number of age- and sex-matched controls. All of the subjects in this study underwent a structured interview and had their vascular risk factors assessed. We reviewed brain magnetic resonance imaging and magnetic resonance angiography data of stroke patients to assessthe severity of white-matter hyperintensity lesions, number of cerebral microbleeds, and the stenosis of both intracranial and extracranial arteries. The baPWV was measured noninvasively by an oscillometric method. Results: The baPWV was most affected by the instantaneous systolic blood pressure, and was significantly higher in stroke patients than control subjects (1,721 ± 395 cm/s vs. 1,657 ± 366 cm/s, p = 0.03). However, the baPWV did not differ significantly with a specific type of stroke or subtype of ischemic stroke. Multiple regression analysis revealed that the baPWV was not independently associated with increased risk of stroke, or the severity of white-matter hyperintensity lesions or cerebral microbleeds. Conclusion: Although the baPWV was significantly higher in stroke patients than control subjects, it was not independently associated with increased risk of stroke or specific subtypes of ischemic stroke or neuroradiological findings.