Utility of standard diffusion-weighted magnetic resonance imaging for the identification of ischemic optic neuropathy in giant cell arteritis.

This study assessed diffusion abnormalities of the optic nerve (ON) in giant cell arteritis (GCA) patients with acute onset of visual impairment (VI) using diffusion-weighted magnetic resonance imaging (DWI). DWI scans of GCA patients with acute VI were evaluated in a case-control study. Two blinded neuroradiologists assessed randomized DWI scans of GCA and controls for ON restricted diffusion. Statistical quality criteria and inter-rater reliability (IRR) were calculated. DWI findings were compared to ophthalmological assessments. 35 GCA patients (76.2 ± 6.4 years; 37 scans) and 35 controls (75.7 ± 7.6 years; 38 scans) were included. ON restricted diffusion was detected in 81.1% (Reader 1) of GCA scans. Localization of ON restricted diffusion was at the optic nerve head in 80.6%, intraorbital in 11.1% and affecting both segments in 8.3%. DWI discerned affected from unaffected ON with a sensitivity, specificity, positive and negative predictive value of 87%/99%/96%/96%. IRR for ON restricted diffusion was κinter = 0.72 (95% CI 0.59-0.86). DWI findings challenged ophthalmologic diagnoses in 4 cases (11.4%). DWI visualizes anterior and posterior ON ischemia in GCA patients with high sensitivity and specificity, as well as substantial IRR. DWI may complement the ophthalmological assessment in patients with acute VI.

Detectability of Retinal Diffusion Restriction in Central Retinal Artery Occlusion is Linked to Inner Retinal Layer Thickness.

PURPOSE: To investigate retinal microstructure differences in central retinal artery occlusion (CRAO) patients with and without visible retinal diffusion restriction (RDR) on diffusion-weighted magnetic resonance imaging (DWI). METHODS: Consecutive CRAO patients with available optical coherence tomography (OCT) and DWI, both performed within 7 days after symptom onset, were included in a retrospective cohort study. The OCT scans were reviewed to assess retinal layer thickness, optical intensity and structural integrity. The OCT findings were compared between patients with and without visible RDR on DWI using Mann-Whitney U or Pearson's Χ2 test. RESULTS: A total of 56 patients (mean age 70.8 ± 12.8 years) were included. RDR was observed in 38 subjects (67.9%) with visually correlating low ADC map in 26 of 38 cases (68.4%). Superior and inferior parafoveal macular thickness measurements (SMT, IMT) of RDR negative patients were significantly lower when compared to RDR+ patients (370.5 ± 43.8 µm vs. 418.2 ± 76.0 µm, p = 0.016; 374.4 ± 42.9 µm vs. 428.8 ± 63.2 µm, p = 0.004) due to differences in inner retinal layer thickness (IRLT, 188.8 ± 34.4 µm vs. 234.7 ± 49.0 µm, p = 0.002). IRLT values of RDR negative patients were higher in 1.5T compared to 3T the DWI (205.0 ± 26.0 µm vs. 168.6 ± 32.8 µm, p = 0.026). CONCLUSIONS: Detectability of RDR is likely contingent upon the degree of ischemic retinal swelling in CRAO. Technical adjustments to the DWI protocol, such as increased field strength, may improve visibility of RDR.

Retinal diffusion restrictions in acute branch retinal arteriolar occlusion.

This study sought to investigate the occurrence of retinal diffusion restrictions (RDR) in branch retinal arteriolar occlusion (BRAO) using standard brain diffusion-weighted imaging (DWI). Two radiologists assessed DWI MRI scans of BRAO patients for RDR in a retrospective cohort study. Inter- and intrarater reliability were calculated using Kappa statistics. Detection rates of RDR were compared among MRI scans with varying field strength, sequence type and onset-to-DWI time intervals. 85 BRAO patients (63.1 ± 16.5 years) and 89 DWI scans were evaluated. Overall sensitivity of RDR in BRAO was 46.1% with visually correlating low ADC signal in 56.1% of cases. Localization of RDR matched distribution of fundoscopic retinal edema in 85% of patients. Inter- and intra-rater agreement for RDR in BRAO was κinter = 0.64 (95% CI 0.48-0.80) and κintra = 0.87 (95% CI 0.76-0.96), respectively. RDR detection rate tended to be higher for 3T, when compared to 1.5T MRI scans (53.7% vs. 34.3%%; p = 0.07). RDR were identified within 24 h up to 2 weeks after onset of visual impairment. RDR in BRAO can be observed by means of standard stroke DWI in a substantial proportion of cases, although sensitivity and interrater reliability were lower than previously reported for complete central retinal artery occlusion.

Time Course and Clinical Correlates of Retinal Diffusion Restrictions in Acute Central Retinal Artery Occlusion.

BACKGROUND AND PURPOSE: Retinal diffusion restrictions were recently identified as a regular finding in acute central retinal artery occlusion. We sought to investigate the influence of technical MR imaging and clinical parameters on the detection rate of retinal diffusion restrictions on standard brain DWI. MATERIALS AND METHODS: In this retrospective cohort study, MR imaging scans of patients with central retinal artery occlusion were assessed by 2 readers for retinal diffusion restrictions on DWI performed within 2 weeks after vision loss. The influence of clinical and technical MR imaging parameters and the time interval between symptom onset and DWI on the presence of retinal diffusion restrictions were evaluated. RESULTS: One hundred twenty-seven patients (mean age, 69.6 [SD 13.9] years; 59 women) and 131 DWI scans were included. Overall, the MR imaging sensitivity of retinal diffusion restrictions in acute central retinal artery occlusion was 62.6%-67.2%. Interrater and intrarater agreement for retinal diffusion restrictions was "substantial" with κinter = 0.70 (95% CI, 0.57-0.83) and κintra = 0.75 (95% CI, 0.63-0.88). Detection of retinal diffusion restrictions did not differ with differences in field strengths (1.5 versus 3T, P = .35) or sequence type (P = .22). Retinal diffusion restrictions were consistently identified within the first week with a peak sensitivity of 79% in DWI performed within 24 hours after symptom onset. Sensitivity of retinal diffusion restrictions declined in the second week (10.0%, P < .001). Absence of retinal diffusion restrictions was more prevalent in patients without fundoscopic retinal edema (60% versus 27.1%, P = .004) and with restitution of visual acuity at discharge (75% versus 28.4%, P = .006). CONCLUSIONS: Retinal diffusion restrictions in acute central retinal artery occlusion can be reliably identified on DWI performed within 24 hours and 1 week after onset of visual impairment. Detectability of retinal diffusion restrictions is dependent on the clinical course of the disease.

Standard Diffusion-weighted MRI for the Diagnosis of Central Retinal Artery Occlusion : A Case-Control Study.

PURPOSE: To evaluate diffusion abnormalities of the retina and optic nerve in patients with central retinal artery occlusion (CRAO) using standard stroke diffusion-weighted magnetic resonance imaging (DWI). METHODS: In this case-control study, DWI scans of patients with nonarteritic CRAO were retrospectively assessed for acute ischemia of the retina and optic nerve. Two neuroradiologists, blinded for patient diagnosis, randomly evaluated DWI of CRAO patients and controls (a collective of stroke and transient ischemic attack [TIA] patients) for restrictions of the retina and optic nerve. We calculated statistical quality criteria and analyzed inter-rater reliability using unweighted Kappa statistics. RESULTS: 20 CRAO patients (60,6 ± 17 years) and 20 controls (60,7 ± 17 years) were included in the study. Sensitivity, specificity, positive and negative predictive values for retinal DWI restrictions were 75%/80%/79%/76% (reader 1) and 75%/100%/100%/80% (reader 2), respectively. Unweighted Kappa was κ = 0,70 (95% CI 0,48­0,92), indicating "substantial" interrater reliability. In comparison, sensitivity, specificity, PPV and NPV (positive and negative predictive values) for restrictions of the optic nerve in CRAO were 55%/70%/65%/61% (reader 1) and 25%/100%/100%/57% (reader 2). Inter-rater reliability was "fair" with unweighted Kappa κ = 0,32 (95% CI 0,09­0,56). CONCLUSIONS: Retinal diffusion restrictions were present in a majority of CRAO patients and detectable with reasonable sensitivity, high specificity and substantial inter-rater reliability. Further studies are necessary to study time dependency of retinal diffusion restrictions, improve image quality and investigate the reliability of retinal DWI to discern CRAO from other causes of acute loss of vision.

Factors associated with fatal outcome in posterior reversible encephalopathy syndrome: a retrospective analysis of the Berlin PRES study.

Although often reversible, fatal outcome in posterior reversible encephalopathy syndrome (PRES) is well known. However, data on predictors of PRES-associated in-hospital death are scarce. In this study, we aimed to investigate predictors of in-hospital death in a large cohort. Radiological report databases between January 1999 and February 2015 were retrospectively searched for patients with PRES. Patients were included if they met criteria for PRES after detailed investigation of clinical charts and imaging studies. Various clinical, paraclinical and brain MRI data as well as data on in-hospital mortality were analyzed. 151 patients were included into the study, 64% were female. Seventeen (11.2%) patients died during hospital stay. In univariate analyses, higher age (p = 0.04), higher levels of C-reactive protein (p < 0.001), etiology of PRES (sepsis and chemotherapy; p = 0.02), altered coagulation (p = 0.002), altered mental state at onset (p = 0.03), and subarachnoid hemorrhage (SAH; p = 0.01) were related to in-hospital death. In multivariate analyses adjusted for age and sex, elevated CRP levels (OR 1.1 95% CI 1.1-1.2), altered coagulation (OR 5.1 95% CI 1.8-14.7), subarachnoid hemorrhage (OR 10.1 95% CI 2.2-46.1) and altered mental state (OR 3.3; 95% CI 1.1-9.4) were independently associated with in-hospital death. Altered mental state, subarachnoid hemorrhage as well as the higher levels of CRP and altered coagulation were significantly more frequent in patients who died in hospital. However, prospective studies are warranted to establish predictors of fatality in patients with PRES.

Important factors determining the nanoscale tracking precision of dynamic microtubule ends.

Tracking dynamic microtubule ends in fluorescence microscopy movies provides insight into the statistical properties of microtubule dynamics and is vital for further analysis that requires knowledge of the trajectories of the microtubule ends. Here we analyse the performance of a previously developed automated microtubule end tracking routine; this has been optimized for comparatively low signal-to-noise image sequences that are characteristic of microscopy movies of dynamic microtubules growing in vitro. Sequences of simulated microtubule images were generated assuming a variety of different experimental conditions. The simulated movies were then tracked and the tracking errors were characterized. We found that the growth characteristics of the microtubules within realistic ranges had a negligible effect on the tracking precision. The fluorophore labelling density, the pixel size of the images, and the exposure times were found to be important parameters limiting the tracking precision which could be explained using concepts of single molecule localization microscopy. The signal-to-noise ratio was found to be a good single predictor of the tracking precision: typical experimental signal-to-noise ratios lead to tracking precisions in the range of tens of nanometres, making the tracking program described here a useful tool for dynamic microtubule end tracking with close to molecular precision.

Discharge status and in-hospital mortality in posterior reversible encephalopathy syndrome.

BACKGROUND: Posterior reversible encephalopathy syndrome is a serious and increasingly recognized disorder, but data from observational studies on outcome and mortality in posterior reversible encephalopathy syndrome (PRES) are scarce. We aimed to determine the frequency and associations of in-hospital death and discharge status in a large cohort of patients with PRES. METHOD: We retrospectively reviewed the radiological report databases of our university hospitals between January 1999 and March 2011 for patients with PRES. Patients fulfilling the criteria for PRES after detailed investigation of clinical charts and imaging studies were included. Clinical charts, paraclinical and brain imaging data at onset as well as available data on in-hospital mortality and discharge status were analyzed. RESULTS: A total of 103 patients were included. Five (4.8%) patients died during hospital stay, 27 (26.2%) remained hospitalized after discharge. In univariate analyses, significant differences were found between patients discharged home from hospital and patients referred to rehabilitation or who died in hospital for the following variables: severe edema (P = 0.013), etiology of PRES (P = 0.001), altered mental state at onset (P = 0.003), altered coagulation (P = 0.004), and length of hospital stay >30 days (P < 0.001). CONCLUSION: Features of a severe course of PRES such as severe edema and altered mental state are significantly more frequent in patients who were referred to inpatient rehabilitation or died in hospital. Prospective studies are warranted to establish factors that are associated with unfavorable outcome in PRES.

Evaluation of intracranial electrocorticography recording strips and tissue partial pressure of oxygen and temperature probes for radio-frequency-induced heating.

Spreading depolarization and subsequent cortical spreading ischemia have been recognized as new mechanisms of ischemic damage in patients with subarachnoid hemorrhage. We are investigating these mechanisms using intracranial implanted devices and perform magnetic resonance imaging (MRI) to monitor for early or delayed ischemia. Before patients undergo MRI with intracranially implanted devices, MR safety with respect to heating induced by radio frequency (RF) needs to be carefully considered. We tested an electrocorticography (ECoG) six-contact electrode strip (Adtech TS06R-SP10X-000) at 1.5 T and a tissue oxygenation/temperature Licox™ probe (model CC1.P1) at 3.0 T for RF-induced heating as MRI safety tests were not available at these field strengths. We observed no relevant temperature increases for the ECoG probe at 1.5 T. For the Licox probe, temperature increased beyond 4°C when measurements were performed at 3.0 T. Our data suggest that MRI can be safely performed in patients with an implanted ECoG electrode strip at 1.5 and 3.0 T. For the Licox probe, MRI can be performed at 1.5 T according to safety regulations, but at 3.0 T, temperature increases pose a significant risk for tissue damage due to RF-induced heating.

Posterior reversible encephalopathy syndrome in children: radiological and clinical findings - a retrospective analysis of a German tertiary care center.

PURPOSE: To report the radiological and clinical spectrum of posterior reversible encephalopathy syndrome (PRES) in children in a German tertiary referral center. METHODS: The radiological report data bases of the authors' university hospitals were searched for paediatric patients with PRES. Clinical and paraclinical data as well as various imaging features at symptom onset and during follow-up were tabulated in patients fulfilling the criteria for PRES. RESULTS: A total of 18 paediatric patients with PRES were included into the study. Mean age was 9 years (IQR 7-12), 38.9% were females. Most frequent predisposing causes were renal and haemato-oncologic diseases frequently associated with endotheliotoxic cytostatic medication. Frontal lesions occurred as frequently as parietal lesions followed by occipital lesions. The superior frontal sulcus topographic lesion pattern occurred as frequent as the parieto-occipital one. In 38% of cases residual lesions were encountered with focal laminar necroses being most frequent. Initial clinical syndromes associated with PRES included seizures in 18, altered mental state in 5, and hemiparesis and visual disturbances in 2 children. Mean arterial blood pressure at onset of PRES was 140/85 mmHg (IQR systolic: 124-169, diastolic: 78-93 mmHg). CONCLUSION: Paediatric PRES in this cohort comprises a broad radiological and clinical spectrum. The occurrence of frontal lesions, a superior frontal sulcus associated lesion pattern, and the development of focal laminar necrosis appear to be frequent in children.

Magnetic resonance imaging in transient global amnesia: lessons learned from 198 cases.

PURPOSE: Patients with transient global amnesia (TGA) present with a characteristic clinical syndrome although other differential diagnoses have to be considered. Diffusion-weighted imaging (DWI) represents a highly specific diagnostic tool in the context of TGA; however, standard clinical DWI often fails to detect the small characteristic hippocampal lesions. The diagnostic success of DWI sequences in TGA patients was analyzed with respect to slice thickness and time interval between symptom onset. METHODS: Magnetic resonance imaging (MRI) studies of 198 patients with clinically diagnosed TGA were retrospectively analyzed. All DWI studies were grouped according to the slice thickness applied (3 mm, 5 mm and 6 mm). The three groups were assessed for group-specific detection rates of hippocampal lesions with diffusion restriction. In addition the detection rates were evaluated with respect to the time interval between TGA symptom onset and MRI examination. RESULTS: A significant increase in detection rates (about 8.4% per mm) was found when thinner slices were acquired (44.7% for 3 mm, 27.1% for 5 mm and 19.6% for 6 mm slice thickness). The detection rate was highest (up to 80%) when MRI was performed 2 days after TGA symptom onset. CONCLUSIONS: The MRI protocol in patients with TGA should include a DWI sequence with a slice thickness of 3 mm or less. The examination should be performed on day 2 after symptom onset to fully exploit the diagnostic value of DWI which represents a sensitive and specific diagnostic tool for patients with TGA.

Clinical and radiological differences in posterior reversible encephalopathy syndrome between patients with preeclampsia-eclampsia and other predisposing diseases.

BACKGROUND: Posterior reversible encephalopathy syndrome (PRES) is a serious maternal complication in pregnancy, but data on the clinicoradiological differences to other etiologies of PRES are scarce. In this study, we aimed to investigate the clinical and imaging characteristics of PRES in preeclampsia-eclampsia patients compared with other predisposing diseases in a large cohort. METHODS: We retrospectively reviewed the radiological report data bases between January 1999 and August 2010 for patients with PRES. Patients fulfilling the criteria for PRES after detailed investigation of clinical charts and imaging studies were separated into patients with eclampsia-preeclampsia and other predisposing causes. Various imaging features at onset of symptoms and on follow-up as well as clinical and paraclinical data were analyzed. RESULTS: A total of 24 patients with preeclampsia-eclampsia associated PRES and 72 patients with PRES of other predisposing causes were included into the study. In preeclampsia-eclampsia patients, headaches were significantly more frequent as initial PRES-related symptom (P < 0.001), whereas altered mental state was significantly less frequent (P = 0.001). Thalamus, midbrain, and pons affection was significantly less frequent in preeclampsia-eclampsia associated PRES (P = 0.01). Preeclampsia-eclampsia patients had significantly less severe edema, less cytotoxic edema, hemorrhage and contrast enhancement, while more frequent complete resolution of edema and less frequent residual structural lesions were seen on follow-up imaging. CONCLUSION: In our PRES cohort, we found major clinicoradiological differences between preeclampsia-eclampsia and other predisposing causes pointing toward a less severe course of disease in preeclampsia-eclampsia.

The clinical and radiological spectrum of posterior reversible encephalopathy syndrome: the retrospective Berlin PRES study.

The aim of the study was to characterize the clinical and radiological spectrum of posterior reversible encephalopathy syndrome (PRES) in a large cohort. The radiological report data bases of the authors' university hospitals were searched for patients with PRES. Various imaging features at onset of symptoms and on follow-up as well as clinical and paraclinical data were tabulated in those patients fulfilling the criteria for PRES. Exploratory univariate analyses were performed. A total of 96 patients with PRES were included into the study. Wide differences in lesion location, diffusivity, distribution pattern, edema severity, hemorrhage, underlying diseases, symptoms, mean arterial pressure (MAP) and coagulation status were encountered. Hemorrhage occurred significantly more frequently in patients with altered coagulation state and was significantly associated with higher edema grades and with the presence of cytotoxic edema. There was a significant difference in MAP between toxic associations with higher MAP in infection, eclampsy and autoimmune disorders, while lower MAP was found in chemotherapy and immunsupression. In 82% of patients complete or near complete resolution of edema was noted during follow-up. Higher MAP levels were associated with incomplete edema resolution. In 43% of patients residual lesions were seen with a relatively even distribution between focal gliosis, infarction, posthemorrhagic residua, atrophy and laminar necrosis. PRES in this large hospital-based retrospective study comprises a wide radiological and clinical spectrum. Residual lesions were encountered more frequently than commonly expected. Our results point towards a differential contribution of high blood pressure to the course of PRES in different underlying etiologies.

Compulsivity predicts fronto striatal activation in severely anorectic individuals.

Anorexia nervosa is a severe illness and shows one of the highest death rates among psychiatric or psychosomatic diseases. However, despite several lines of research, the etiology of this disease is still unknown. One of those features is the rigidity of behaviors, for example, controlling of weight and pursuing of thinness, that often meets the criteria for obsessive-compulsive behavior. In this study, it was investigated whether the clinical feature of compulsivity in anorexia nervosa patients relates to regional brain activation. Using functional magnetic resonance imaging, 12 severely anorectic women were compared to 12 normal-weight female individuals following a cue-reactivity paradigm. Cues comprised food cues of high and low calorie content as well as eating-related utensils. Voxel-based morphometric analysis indicated significantly overall reduced gray matter volume and significantly increased cerebrospinal fluids in anorexia nervosa (AN) patients, which was controlled for in subsequent analyses. Following the high-calorie stimulation, AN patients activated the right caudate body and right precuneus, whereas control subjects did not show significant regional activations. In both other conditions, low-calorie foods and eating utensils, regional brain activations did not survive FDR thresholds. During the high-calorie condition, compulsivity, that is, the subscore "obsessive thoughts," predicted activation of the superior frontal gyrus [Brodmann areas (BA) 10], inferior frontal gyrus, anterior cingulate cortex (BA 32), cingulate gyrus (BA 24), caudate body, cuneus, pre- and postcentral gyrus. The subscore "compulsive acts" correlated with activation of the claustrum during the high-calorie condition and predicted a number of deactivations of frontal and temporal regions. We conclude that in severely anorectic individuals, the degree of compulsivity predicts activation and deactivation of the fronto-striatal pathway.

Olfactory bulb volume and olfactory function in patients with multiple sclerosis.

BACKGROUND: Some studies reported olfactory dysfunction in patients with multiple sclerosis (MS). There is no agreement about the most suitable testing method for measuring olfactory function (OF) in MS patients. Recent studies showed that olfactory bulb volume changes with the degree of olfactory dysfunction. We assessed olfactory bulb volume of MS patients with magnetic resonance imaging (MRI) and related it to the OF. MATERIAL AND METHODS: Volumetric measurements of the right and left olfactory bulb (OB) were performed by manual segmentation within 36 MS patients. Psychophysical testing of the orthonasal OF was performed using threshold-discrimination-identification (TDI) score in MS patients. RESULTS: Of all MS patients, 44.4% displayed olfactory dysfunction. The TDI score of all 36 MS patients, especially the score of the Identification subtest correlated strongly with neurological scores typical of MS. In patients with a decreased OB volume, there was a positive correlation between volumetry of the OB and OF. CONCLUSION: OB volumes may provide valuable information about MS patients with olfactory dysfunction. The TDI test and Identification subtest were very sensitive in detecting olfactory dysfunction in MS patients.

[Pathological changes of the chemosensory function in multiple sclerosis - an MRI study]. / Pathologische Veränderungen der Chemosensorik mittels Kernspintomografie bei Multipler Sklerose - eine MRT-Studie.

PURPOSE: To examine possible causes for olfactory and gustatory dysfunction in MS patients in a prospective study with MRI. MATERIALS AND METHODS: 30 MS patients (21 women, 11 men, 22 - 65 years, Ø 42 years) were examined by MRI. The olfactory bulb (OB) and olfactory brain volume was correlated with the number and volume of MS lesions in the olfactory brain and the non-olfactory brain. Olfactory testing was performed using the Threshold-Discrimination-Identification Test (TDI), and gustatory function was tested using the Taste-Strips-Test (TST). RESULTS: 33 % of the MS patients displayed olfactory dysfunction (8 % of the control group), and 17 % displayed gustatory dysfunction (5 % of the control group). There was a correlation between the olfactory brain volume and the number (r = -0.38, p < 0.05) and volume (r = -0.38, p < 0.05) of MS lesions in the olfactory brain. The olfactory brain volume correlated with the number of MS lesions in the non-olfactory brain (r = -0.48, p < 0.05). The volume of the left OB correlated with the volume of MS lesions in the olfactory brain (r = -0.42, p < 0.05), the number (r = 0.37, p < 0.05) and volume (r = 0.4, p < 0.05) of lesions in the left part of the olfactory brain and with the TST score (r = -0.45, p < 0.05). The TST score correlated with the volume of lesions in the left (r = -0.45, p < 0.05) and right part (r = -0.53, p < 0.05) of the olfactory brain. The TST score correlated with the number of lesions in the non-olfactory brain (r = -0.48, p < 0.05). CONCLUSION: The correlation between a higher number and volume of MS lesions in the olfactory brain with a decreased OB and olfactory brain volume could help to explain olfactory and gustatory dysfunction in MS patients. Just the left OB correlated with the number and volume of lesions in the olfactory brain. Manual segmentation was a suitable method for measuring OB and olfactory brain volume.

Image quality and radiation exposure in 320-row temporal bone computed tomography.

OBJECTIVES: The aim was to define image quality and radiation exposure in the recently introduced 320-row CT of the temporal bone (tb) in comparison to a 16-row tb CT. METHODS: A cadaveric head phantom was used for repeated tb volume CT studies (80-120 kV, 25-150 mAs), performed in a 320-row scanner (single rotation, 0.5 mm slice thickness, kernel FC 51) in comparison to 16-row helical CT using standard acquisition parameters (SAP) of 120 kV and 75 mAs (kernel FC 53). Qualitative image evaluation was performed by two radiologists using a 5-point visual analogue scale. Image noise (D(SD)) was determined by region of interest (ROI) based measurements in cadaveric as well as water phantom studies. Dosimetric measurements of the effective dose (ED) and organ dose (OD) of the lens were performed. RESULTS: Image quality of 320-row tb CT was equivalent to 16-row CT for SAP scans, resulting in image noise levels (D(SD) 16-/320-row) of 109/237 and 206/446 for air and bone respectively. D(SD) differences were predominantly (>90%) attributable to the different kernels available for tb studies in 16- and 320-row CT. Radiation exposure for 16-/320-row SAP scans amounted to 0.36/0.30 mSv (ED) and 10.0/8.4 mGy (lens dose). CONCLUSION: 320-row volume acquisition in tb CT delivers equivalent image quality to 16-row CT while decreasing radiation exposure figures by one sixth. Image noise increase in 320-row CT is negligible with respect to image quality.

Dose exposure of patients undergoing comprehensive stroke imaging by multidetector-row CT: comparison of 320-detector row and 64-detector row CT scanners.

BACKGROUND AND PURPOSE: Recently introduced 320-detector row CT enables whole brain perfusion imaging compared to a limited scanning area in 64-detector row CT. Our aim was to evaluate patient radiation exposure in comprehensive stroke imaging by using multidetector row CT consisting of standard CT of the head, CTA of cerebral and cervical vessels, and CTP. MATERIAL AND METHODS: Organ doses were measured by using LiF-TLDs located at several organ sites in an Alderson-Rando phantom. Effective doses were derived from these measurements. Stroke protocols including noncontrast head CT, CTA of cerebral and cervical vessels, and CTP were performed on 320- and 64-detector row scanners. RESULTS: Measured effective doses for the different scanning protocols ranged between 1.61 and 4.56 mSv, resulting in an effective dose for complete stroke imaging of 7.52/7.54 mSv (m/f) for 64-detector row CT and 10.56/10.6 mSv (m/f) for 320-detector row CT. The highest organ doses within the area of the primary beam were measured in the skin (92 mGy) and cerebral hemispheres (69.91 mGy). Use of an eye-protection device resulted in a 54% decrease of the lens dose measured for the combo protocol for whole-brain perfusion with the 320-detector row CT scanner. CONCLUSIONS: Phantom measurements indicate that comprehensive stroke imaging with multidetector row CT may result in effective radiation doses from 7.52 mSv (64-detector row CT) to 10.6 mSv (320-detector row CT). The technique of 320-detector row CT offers additional information on the time course of vascular enhancement and whole-brain perfusion. Physicians should weigh the potential of the new technique against the higher radiation dose that is needed. Critical doses that would cause organ damage were not reached.