Contrast dependence of scattering profiles for poly(ethylene glycol) in water: Investigation by small-angle neutron scattering with 3He spin filter and small-angle x-ray scattering.

The small-angle neutron scattering (SANS) and small-angle x-ray scattering (SAXS) measurements were performed for deuterated and non-deuterated poly(ethylene glycol) (d-PEG and h-PEG, respectively) in D2O and a D2O/H2O mixed solvent (Mix) to compare the scattering profiles. To determine the coherent scattering intensity of SANS, a 3He spin filter was utilized. The scattering profiles determined by the SANS measurements were analyzed in terms of the wormlike chain model with touched beads along the contour of the chain. However, the SAXS profiles were not explained by the same model with uniform beads but with beads each consisting of a core and a shell having different electron densities. To explore the chain thickness determined from the SANS profile, the scattering intensities for different combinations of d-PEG/D2O, d-PEG/Mix, h-PEG/D2O, and h-PEG/Mix were also examined.

Impact of beam collimation of z-overscanning on dose to the lens and thyroid gland in paediatric thoracic computed tomography imaging.

BACKGROUND: Adaptive collimation reduces the dose deposited outside the imaged volume along the z-axis. An increase in the dose deposited outside the imaged volume (to the lens and thyroid) in the z-axis direction is a concern in paediatric computed tomography (CT). OBJECTIVE: To compare the dose deposited outside the imaged volume (to the lens and thyroid) between 40-mm and 80-mm collimation during thoracic paediatric helical CT. MATERIALS AND METHODS: We used anthropomorphic phantoms of newborns and 5-year-olds with 40-mm and 80-mm collimation during helical CT. We compared the measured dose deposited outside the imaged volume using optically stimulated luminescence dosimeters (OSLD) at the surfaces of the lens and thyroid and the image noise between the 40-mm and 80-mm collimations. RESULTS: There were significant differences in the dose deposited outside the imaged volume (to the lens and thyroid) between the 40-mm and 80-mm collimations for both phantoms (P < 0.01). CONCLUSION: Compared with that observed for 80-mm collimation in helical CT scans of the paediatric thorax, the dose deposited outside the imaged volume (to the lens and thyroid) was significantly lower in newborns and 5-year-olds with 40-mm collimation.

Comparison of pediatric lens scattered dose measurements between axial 40-mm and helical 160-mm detector width computed tomography scan modes.

BACKGROUND: Reports comparing field lens doses between helical scans with a 40-mm detector width and axial scans with a 160-mm detector width using different computed tomography (CT) scanners are currently scarce. OBJECTIVE: To compare scatter doses for lenses between a helical scan with a 40-mm detector width and an axial scan with a 160-mm detector width when using different CT scanners in the context of pediatric chest examinations. MATERIALS AND METHODS: Two different CT machines were used: Revolution CT (GE Healthcare, Waukesha, WI) with a 256-row, 0.625-mm multidetector; and Aquilion ONE GENESIS Edition (Canon Medical Systems, Otawara, Japan) with a 320-row, 0.5-mm multidetector. Three pediatric anthropomorphic phantoms were used, with optically stimulated luminescence dosimeters (OSLDs) placed on the left and right lenses. The scatter dose values measured by the OSLDs were compared between a helical scan with a 40-mm detector width and an axial scan with a 160-mm detector width during pediatric chest CT examinations. RESULTS: Median equivalent doses for the helical and axial scans were 0.12 and 0.12 mSv/mGy for the newborn, 0.17 and 0.16 mSv/mGy for the 1-year-old, and 0.18 and 0.15 mSv/mGy for the 5-year-old, respectively, when using the Revolution CT. With the Revolution CT, no significant differences were observed in the scatter doses between helical and axial scans in the newborn and 1-year-old phantoms. However, the lens scatter dose for the helical scan was approximately 20-35% higher than that for the axial scan in the 5-year-old phantom (P<0.01). The median equivalent doses of eye lenses for the helical and axial scans were 0.12 and 0.07 mSv/mGy for the newborn, 0.07 and 0.05 mSv/mGy for the 1-year-old, and 0.14 and 0.12 mSv/mGy for the 5-year-old, respectively, when using the Aquilion ONE. With the Aquilion ONE, lens scatter doses for the helical scan were approximately 70%, 40%, and 30% higher in the newborn, 1-year-old, and 5-year-old phantoms, respectively, than those for the axial scan (P<0.01). CONCLUSIONS: When using the Aquilion ONE, lens scatter doses for the helical scan were significantly higher in all three phantoms than those for the axial scan. In contrast, when using the Revolution CT, the lens scatter dose for the helical scan was significantly higher in the 5-year-old phantom than that for the axial scan. These results suggest that although scattered doses may vary with respect to the CT scanner and body size, they are generally lower in the case of axial scans.

[New Potential Method for Optimizing the ATCM Technique in Pediatric CT Examination].

PURPOSE: To compare the radiation dose and image quality using the conventional method for performing the front and side scout view and a new method for performing the side scout view, and then correct the table height at the scan isocenter and perform the front scout view. METHODS: We retrospectively analyzed fifty-six children who had underwent computed tomography (CT) examination between June 2014 and August 2018. We divided them into two groups. The conventional method was performed in 3 steps: 1. obtain the front scout view, 2. obtain the side scout view, and 3. main scan. Without table position correction, the new method was performed in 4 steps: 1. obtain the side scout view with table position correction, 2. patient correction at the scan isocenter, 3. obtain the front scout view, and 4. main scan. We used a 64-row CT scanner (LightSpeed VCT; GE Healthcare). Scan parameters were tube voltage 80 kV, automatic tube current modulation, noise index 16, slice thickness 5 mm, rotation time 0.4 s/rot, helical pitch 1.375, and reconstruction kernel standard. We recorded the volume dose index (CTDIvol) and dose length product (DLP) on the CT console and compared the radiation dose in both groups. To evaluate the image quality in both groups, the mean standard deviation of CT number (SD value) was measured within an approximately 5-10 mm2  circular region of interest. We measured the scan length of the pediatric patient and accuracy of pediatric positioning at the CT examination. A grid was displayed on the CT axial image, taken to evaluate the error from the scan isocenter during alignment, and the error between the height of half the body thickness and the scan isocenter was recorded. RESULTS: Scan lengths were median (minimum-maximum) values of 16.2 cm (10.8-21.5 cm) and 16.8 cm (11.5-23.0 cm). There were no significant differences in the scan length between both groups (p=0.47). In the group with table position correction, median (minimum-maximum) values for CTDIvol, DLP and SD value were 0.40 mGy (0.3-0.7 mGy), 7.6 mGyï½¥cm (4.4-11.5 mGyï½¥cm), and 24.0 HU (18.3-37.5 HU), respectively. In the group without the table position correction, median (minimum-maximum) values for CTDIvol, DLP and SD value were 0.40 mGy (0.3-0.6 mGy), 7.1 mGyï½¥cm (4.2-13.8 mGyï½¥cm), and 20.3 HU (11.3-28.8 HU), respectively. There were no significant differences in the CTDIvol and DLP values between both groups (p=0.42 and p=0.44, respectively); however, there were significant differences in the SD value in both groups (p<0.01). The error for the accuracy of pediatric positioning was 0 mm (0 to 0 mm) and 10 mm (-16 to+59 mm) using the conventional and new methods (p<0.01), respectively. CONCLUSIONS: It was suggested that the optimum image could be obtained during CT scan with automatic tube current modulation by using this potential new method (1. obtain the side scout view, 2. patient correction at the scan isocenter, 3. obtain the side scout view, and 4. main scan).

Cilostazol decreases duration of spreading depolarization and spreading ischemia after aneurysmal subarachnoid hemorrhage.

OBJECTIVE: Traditionally, angiographic vasospasm (aVS) has been thought to cause delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). However, successful treatment of aVS alone does not result in improved neurological outcome. Therefore, there may be other potential causes of poor neurological outcome, including spreading depolarization (SD). A recent study showed beneficial effects of cilostazol on DCI and neurological outcome. The present prospective clinical trial and experimental study focused on effects of cilostazol on SDs. METHODS: Fifty aSAH patients were treated with clip ligation and randomly assigned to a cilostazol (n = 23) or control group (n = 27). Effects of cilostazol on DCI, aVS, and SDs, measured with subdural electrodes, were examined. The effect of cilostazol on SD-induced perfusion deficits (spreading ischemia) was assessed in an aSAH-mimicking model. RESULTS: There was a trend for less DCI in the cilostazol group, but it did not reach our threshold for statistical significance (13.0% vs 40.0%, odds ratio = 0.266, 95% confidence interval [CI] = 0.059-1.192, p = 0.084). However, the total SD-induced depression duration per recording day (22.2 vs 30.2 minutes, ß = -251.905, 95% CI = -488.458 to -15.356, p = 0.043) and the occurrence of isoelectric SDs (0 vs 4 patients, ß = -0.916, 95% CI = -1.746 to -0.085, p = 0.037) were significantly lower in the cilostazol group. In rats, cilostazol significantly shortened SD-induced spreading ischemia compared to vehicle (Student t test, difference = 30.2, 95% CI = 5.3-55.1, p = 0.020). INTERPRETATION: Repair of the neurovascular response to SDs by cilostazol, as demonstrated in the aSAH-mimicking model, may be a promising therapy to control DCI. Ann Neurol 2018;84:873-885.

[Usefulness of Fenestrated Catheters for i.v. Contrast Infusion Cardiac CT Angiography for Newborn Patients during the Congenital Heart Disease].

PURPOSE: A three-dimensional (3D) image from computed tomography (CT) angiography is a useful method for evaluation of complex anatomy such as congenital heart disease. However, 3D imaging requires high contrast enhancement for distinguishing between blood vessels and soft tissue. To improve the contrast enhancement, many are increasing the injection rate. However, one method is the use of fenestrated catheters, it allows use of a smaller gauge catheter for high-flow protocols. The purpose of this study was to compare the pressure of injection rate and CT number of a 24-gauge fenestrated catheter with an 22-gauge non-fenestrated catheter for i.v. contrast infusion during CT. METHODS: Between December 2014 and March 2015, 50 newborn patients were randomly divided into two protocols; 22-gauge conventional non-fenestrated catheter (24 newborn; age range 0.25-8 months, body weight 3.6±1.2 kg) and 24-gauge new fenestrated catheter (22 newborn; age range 0.25-12 months, body weight 3.3±0.9 kg). Helical scan of the heart was performed using a 64-detector CT (LightSpeed VCT, GE Healthcare) (tube voltage 80 kV; detector configuration 64×0.625 mm, rotation time 0.4 s/rot, helical pitch 1.375, preset noise index for automatic tube current modulation 40 at 0.625 mm slice thickness). RESULTS: We compared the maximum pressure of injection rate, CT number of aortic enhancement, and CT number of pulmonary artery enhancement between both protocols. The median injection rate, CT number of aortic enhancement, and CT number of pulmonary artery enhancement were 0.9 (0.5-3.4) ml/s, 455.5 (398-659) HU, and 500.0 (437-701) HU in 22-gauge conventional non-fenestrated catheter and 0.9 (0.5-2.0) ml/s, 436.5 (406-632) HU, and 479.5 (445-695) HU in the 24-gauge fenestrated catheter, respectively. There are no significantly different between a 24-gauge fenestrated catheter and 22-gauge non-fenestrated catheters at injection rate and CT number. Maximum pressure of injection rate was lower with 24-gauge non-fenestrated catheters (0.33 kg/cm2) than 22-gauge non-fenestrated catheters (0.55 kg/cm2) (p<0.01Conclusion: A 24-gauge fenestrated catheter performs similarly to an 22-gauge non-fenestrated catheter with respect to i.v. contrast infusion and aortic enhancement levels and can be placed in most subjects whose veins are deemed insufficient for an 22-gauge catheter.

Relationship between the radiation doses at nonenhanced CT studies using different tube voltages and automatic tube current modulation during anthropomorphic phantoms of young children.

To compare the radiation dose and image noise of nonenhanced CT scans performed at 80, 100, and 120 kVp with tube current modulation (TCM) we used anthropomorphic phantoms of newborn, 1-year-old, and 5-year-old children. The noise index was set at 12. The image noise in the center of the phantoms at the level of the chest and abdomen was measured within a circumscribed region of interest. We measured the doses in individual tissues or organs with radio-photoluminescence glass dosimeters for each phantom. Various tissues or organs were assigned and the radiation dose was calculated based on the international commission on radiological protection definition. With TCM the respective radiation dose at tube voltages of 80, 100, and 120 was 29.71, 31.60, and 33.79 mGy for the newborn, 32.00, 36.79, and 39.48 mGy for the 1-year-old, and 32.78, 38.11, and 40.85 mGy for the 5-year-old phantom. There were no significant differences in the radiation dose among the tube voltages and phantoms (P > 0.05). Our comparison of the radiation dose using anthropomorphic phantoms of young children showed that the radiation dose of nonenhanced CT performed at different tube voltages with TCM was not significantly different.

Safety and Time Course of Drip-and-Ship in Treatment of Acute Ischemic Stroke.

BACKGROUND: The drip-and-ship approach allows intravenous tissue plasminogen activator therapy and adjuvant endovascular treatment in acute ischemic stroke, even in rural areas. Here, we examined the safety and time course of the drip-and-ship approach. METHODS: Fifty consecutive cases treated with the drip-and-ship approach (drip-and-ship group) in June 2009 to March 2016 were retrospectively examined. Changes in mean blood pressure, systemic complications, and neurological complications were compared according to method of transportation. Time courses were compared between drip-and-ship and direct admission groups during the same period. RESULTS: In the drip-and-ship group, 33 and 17 patients were transferred to hospital by ambulance and helicopter, respectively. One patient suffered hemorrhagic infarction during transportation by ambulance. Mean blood pressure change was lower in patients transferred by helicopter than ambulance (<5 mmHg versus 12.2 mmHg, respectively). The mean onset-to-door times in the drip-and-ship and direct admission groups were 71 and 64 minutes, respectively, and mean door-to-needle times were 70 and 47 minutes, respectively (P =.002). Although mean transportation time from the primary stroke hospital to our hospital was 32 minutes, the entry-to-exit time from the primary stroke hospital was 113 minutes. Thereafter, there was an average delay of 100 minutes until reperfusion compared with the direct admission group. CONCLUSIONS: Drip-and-ship was relatively safe in this small series. Transportation by helicopter was less stressful for acute ischemic stroke patients. It is important to reduce door-to-needle time and needle-to-departure time in the primary stroke hospital to minimize the time until treatment in cases of acute ischemic stroke.

Multiple encephalogaleoperiosteal synangiosis for bilateral carotid artery stenosis in a 13-year-old girl: a case report.

INTRODUCTION: Encephalogaleoperiosteal synangiosis (EGS) has been widely used to treat children with moyamoya disease (MMD). We present the first case of successful multiple EGS in a patient with brain ischemic disease who presented with different cerebrovascular findings from MMD. METHODS: A 13-year-old girl had an increased frequency of transient ischemic attacks that affected her right extremities. Digital subtraction angiography showed tapering of the internal carotid artery (ICA). The anterior cerebral artery (ACA) and middle cerebral artery (MCA) were visible on vertebral angiogram, but not on carotid angiogram. The intact circle of Willis and lack of hypervascularity of the lenticulostriate arteries were observed. Decreased regional cerebral blood flow (CBF) in the bilateral ACA and MCA territories quantified by (123)I-N-isopropyl-p-iodoamphetamine-single photon emission computed tomography indicated the need for extracranial-intracranial bypass surgery. Multiple EGS procedures were performed instead of direct anastomosis, which is the standard procedure for intracranial ICA stenosis, because the space for the craniotomy was limited by transdural anastomosis. RESULTS: Despite the fact that the diagnosis of MMD was questionable, the hemispheres were well vascularized, and the neurology and CBF improved postoperatively. CONCLUSION: The preserved circle of Willis and lack of moyamoya vessels were inconsistent with the features of MMD. However, childhood onset, bilateralness, chronic intracranial ICA stenosis, and transdural anastomosis indicated the same underling pathogenicity as MMD. It is hypothesized that ICA stenosis occurred immediately proximal to the posterior communicating artery in this case. This would have produced the atypical finding of the remaining circle of Willis without growth of the basal moyamoya vessels.

Importance of Early Postoperative Body Temperature Management for Treatment of Subarachnoid Hemorrhage.

BACKGROUND: The importance of acute-phase brain temperature management is widely accepted for prevention of exacerbation of brain damage by a high body temperature. METHODS: In this study, we investigated the influence of body temperature in the early postoperative period on the outcomes of 62 patients with subarachnoid hemorrhage who were admitted to our department. Body temperature was measured from day 4 to day 14 after onset. The patients were divided into those treated with surgical clipping (clip group) and coil embolization (coil group), those graded I-III (mild) and IV-V (severe) based on the Hunt & Hess classification on admission, those with and without development of delayed cerebral ischemia (DCI), and those with favorable and poor outcomes. Body temperatures throughout the hospital stay were compared in each group. RESULTS: There was no significant difference in body temperature between the clip and coil groups or between the mild and severe groups, but body temperature was significantly higher in patients with DCI compared to those without DCI, and in patients with a poor outcome compared to those with a favorable outcome. CONCLUSIONS: Fever in the early postoperative period of subarachnoid hemorrhage is associated with development of DCI and a poor outcome.

Continuous Monitoring of Spreading Depolarization and Cerebrovascular Autoregulation after Aneurysmal Subarachnoid Hemorrhage.

Delayed cerebral ischemia (DCI) is a prominent complication after aneurysmal subarachnoid hemorrhage (aSAH). Although vasospasm of proximal cerebral arteries has been regarded as the main cause of DCI, vasospasm of distal arteries, microthrombosis, impaired autoregulation, cortical spreading depolarization (CSD), and spreading ischemia are thought to be involved in DCI after aSAH. Here, we describe a patient with aSAH in whom CSD and cerebrovascular autoregulation were evaluated using simultaneous electrocorticography and monitoring of the pressure reactivity index (PRx) after surgical clipping of a ruptured posterior communicating artery aneurysm. In this patient, a prolonged duration of CSD and elevation of PRx preceded delayed neurological deficit. Based on this observation, we propose a relationship between these factors and DCI. Assessment of cerebrovascular autoregulation may permit detection of the inverse hemodynamic response to cortical depolarization. Detection of DCI may be achieved through simultaneous monitoring of CSD and PRx in patients with aSAH.

Decreased Flow Velocity with Transcranial Color-Coded Duplex Sonography Correlates with Delayed Cerebral Ischemia due to Peripheral Vasospasm of the Middle Cerebral Artery.

BACKGROUND AND OBJECTIVE: Despite intensive therapy, vasospasm remains a major cause of delayed cerebral ischemia (DCI) in worsening patient outcome after aneurysmal subarachnoid hemorrhage (aSAH). Transcranial Doppler (TCD) and transcranial color-coded duplex sonography (TCCS) are noninvasive modalities that can be used to assess vasospasm. However, high flow velocity does not always reflect DCI. The purpose of this study was to investigate the utility of TCD/TCCS in decreasing permanent neurological deficits. METHODS: We retrospectively enrolled patients with aSAH who were treated within 72 hours after onset. TCCS was performed every day from days 4 to 14. Peak systolic velocity (PSV), mean velocity (MV), and pulsatility index were recorded and compared between DCI and non-DCI patients. In patients with DCI, endovascular therapy was administered to improve vasospasm, which led to a documented change in velocity. RESULTS: Of the 73 patients, 7 (9.6%) exhibited DCI. In 5 of the 7 patients, DCI was caused by vasospasm of M2 or the more peripheral middle cerebral artery (MCA), and the PSV and MV of the DCI group were lower than those of the non-DCI group after day 7. Intra-arterial vasodilator therapy (IAVT) was performed for all patients with DCI immediately to increase the flow volume by the next day. CONCLUSIONS: Increasing flow velocity cannot always reveal vasospasm excluding M1. In patients with vasospasm of M2 or more distal arteries, decreasing flow velocity might be suggestive of DCI. IAVT led to increases in the flow velocity through expansion of the peripheral MCA.

Vessel Visibility Assessment of Low Tube Voltage Coronary Computed Tomography Angiography Determined with Contrast-to-Noise Ratio.

PURPOSE: The purpose of this study was to investigate the association of vessel visibility and radiation dose using contrast-to-noise ratio (CNR) method with low tube voltage in coronary computed tomography angiography (c-CTA). METHODS: We performed electrocardiogram-gated scan of 2.0-mm diameter simulated vessel in the center of the cardiac phantom by the use of a 64-detector CT scanner. Reference CNR was calculated from the target coronary CT number (CTnumberA; 350 Hounsfield units [HU]), epicardial fat CT number (CTnumberB; -100 HU), and target epicardial fat standard deviation (SD) number (SDB; 25 HU) at the 120 kV. We obtained the tube current at low tube voltage (100 and 80 kV) to perform the similar reference CNR at 120 kV. The full widths at half maximum from axial images were evaluated with quantitative evaluation and three types of visualizations of the vessel phantom were evaluated with the qualitative evaluations. RESULTS: CTnumberA of 100 and 80 kV were increased by 26% and 50%, respectively, compared with 120 kV (P<0.01). SDB was also increased by a similar ratio (P<0.01). CTDIvol of 100 and 80 kV were decreased by 39% and 51%, respectively, compared with 120 kV (P<0.05). There were no significant voltage differences among three tubes in quantitative and qualitative evaluations at the same CNR (P> 0.05). CONCLUSION: In this phantom study, these results show that the CNR method with low tube voltage achieves radiation dose reduction without decreasing the image quality.

Multiple ischemic strokes caused by nonbacterial thrombotic endocarditis because of gallbladder cancer: a case report.

We report a case of a 62-year-old woman with multiple ischemic strokes caused by nonbacterial thrombotic endocarditis (NBTE) because of gallbladder cancer. Transesophageal echocardiography showed NBTE on the mitral valve. The NBTE disappeared with anticoagulation treatment for 2 weeks. Abdominal computed tomography showed a gallbladder tumor that was surgically resected. Histopathologic studies showed poorly differentiated tumor cells and the production of mucin. Trousseau syndrome with gallbladder cancer is very rare. We suggest that the development of NBTE is related to the production of mucin.

Safety of Tailored Transfemoral Carotid Artery Stenting for Symptomatic Elderly Patients: A Single Center Observational Study.

OBJECTIVE: Transfemoral carotid artery stenting (TFCAS) in symptomatic elderly patients (≥70 years old) may have a high periprocedural stroke rate. This study was performed to examine whether tailored TFCAS for symptomatic elderly patients is as safe as that for symptomatic nonelderly patients. METHODS: The subjects were 185 patients with symptomatic internal carotid artery stenosis. Tailored TFCAS including postoperative management was performed based on preoperative examinations of vascular anatomy, plaque imaging, platelet aggregation activity, and cerebral hemodynamic impairment. The major 30-day perioperative stroke rates were examined. RESULTS: The patients included 51 (27.6%) <70 (group Y) and 134 (72.4%) ≥70 (group E) years old. Group E included significantly more cases with an elongated aortic arch, tortuous target lesion, and longer plaques (all P < 0.05). Among all cases, 181 (97.8%) procedures were performed as per preoperative planning. Group E had more frequent use of a proximal embolic protection device and a closed-cell or dual-layer micromesh stent (all P < 0.05). Seven patients (3.8%) had major stroke. Rates of major ischemic stroke (2.0% vs. 3.0%, P = 1.00) and intracranial hemorrhage (2.0% vs. 0.8%, P = 0.48) were low and did not differ significantly between groups Y and E. CONCLUSIONS: Symptomatic elderly patients have several unfavorable factors. However, tailored TFCAS for each patient based on preoperative examinations in symptomatic elderly patients may be as safe as that in symptomatic nonelderly patients.

Cardiac computed tomography angiography with and without bolus tracking methods in infants with congenital heart disease.

The study investigated radiation dose, vascular computed tomography (CT) enhancement and image quality of cardiac computed tomography angiography (CCTA) with and without bolus tracking (BT) methods in infants with congenital heart disease (CHD). The volume CT dose index (CTDIvol) and dose length product (DLP) were recorded for all CT scans, and the effective dose was obtained using a conversion factors. The CT number for the ascending aorta (AO) and pulmonary artery (PA), image noise of muscle tissue and contrast-to-noise ratio (CNR) were measured and calculated. The median values in the groups with and without BT were 2.20 mGy versus 0.44 mGy for CTDIvol, 8.10 mGy·cm versus 6.20 mGy·cm for DLP, and 0.66 mSv versus 0.51 mSv for effective dose (p < 0.001). There were no statistical differences in vascular CT enhancement, image noise, and CNR. CCTA without BT methods can reduce the radiation dose while maintaining vascular CT enhancement and image quality compared to CCTA with BT methods.

Effectiveness of low tube voltage scan in the exposure dose for lenses during paediatric thoracic CT examination: anthropomorphic phantoms study.

To determine whether using lower-tube voltage reduces the scattered dose for the lens during paediatric thoracic computed tomography (CT). Two paediatric anthropomorphic phantoms (ATOM Phantom, CIRS, Norfolk, Virginia, USA) representing a newborn and 5-year-old were placed on the gantry of CT scanner, and optically stimulated luminescence dosemeters were placed on the left and right lenses, in front of the left and right thyroid glands, in front of the left and right mammary glands, and in front of and behind the mammary gland level and we measured scattered dose of the optically stimulated luminescence dosemeter was compared for each phantom between 80 and 120 kVp. Significant differences were observed in the scatter doses for the lens between 80 and 120 kVp (p < 0.01). Compared with the 120 kVp scan, the scatter doses for the lens were ~15-40% lower in newborn and 5-year-olds using the 80 kVp scan during paediatric CT.

Comparison of the equivalent doses of the eye lenses, thyroid, and mammary gland among three pediatric and one adult anthropomorphic phantom during the chest CT examinations using a 40 mm volume helical scan.

Equivalent doses for the eye lenses, thyroid, and mammary glands were measured and compared between one adult and three pediatric anthropomorphic phantoms during chest computed tomography (CT) using 40 mm volume helical scan on the Aquilion ONE GENESIS Edition CT equipment. Placing an optically stimulated luminescence dosemeter (OSLD) on the eye lenses, thyroid, and mammary gland, we measured and compared the equivalent dose of OSLD among different phantoms during chest CT using a helical scan. Compared with adults, the equivalent doses to the eye lens, thyroid, and mammary glands were ~81%, 77%, and 63% lower in newborns, 1-year-olds, and 5-year-olds using comparable image noise during chest CT.

Cerebral hemodynamic benefits after carotid artery stenting in patients with near occlusion.

OBJECTIVE: The natural history and management of patients with near occlusion (NO) of the internal carotid artery are controversial. In particular, it is unclear whether cerebral hemodynamics are compromised in these patients and whether improvement by carotid revascularization leads to the prevention of ischemic stroke. In this study, we measured cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) using single-photon emission computed tomography before and after carotid artery stenting (CAS) for NO to examine the effectiveness of CAS from the perspective of cerebral hemodynamics. METHODS: CAS was performed in 15 patients with NO and in 78 with severe stenosis (≥70%) but without NO at our institution. Resting CBF and CVR to acetazolamide were measured using N-isopropyl-p-[I-123] iodoamphetamine single-photon emission computed tomography before and at 3 to 6 months after CAS. We also measured CBF using the same method for healthy individuals and compared the results among the three groups. RESULTS: CAS was successfully performed in all patients. Before CAS, the mean resting CBF was 26.68 ± 4.23 mL/100 g/min, and the mean CVR was -0.8% ± 15.1% in the patients with NO, both of which were significantly lower than in patients with severe stenosis without NO and in healthy individuals. After CAS, the mean resting CBF and mean CVR in patients with NO increased significantly to 30.07 ± 5.67 mL/100 g/min and 37.0% ± 21.4%, respectively, and there were no significant differences among the three groups. CONCLUSIONS: Before CAS, patients with NO were more hemodynamically compromised than those with severe stenosis without NO. After CAS, significant cerebral hemodynamic improvement and normalization occurred long-term. Thus, from a hemodynamic perspective, CAS was effective in patients with NO.