Comparison between perfusion computed tomography and dynamic contrast-enhanced magnetic resonance imaging in assessing glioblastoma microvasculature

PurposePerfusion computed tomography (PCT) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) provide independent measurements of biomarkers related to tumor perfusion. The aim of this study was to compare the two techniques in assessing glioblastoma microvasculature.Materials and methodsTwenty-five patients diagnosed with glioblastoma (14 males and 11 females; 51 ± 11 years old, ranging from 33 to 70 years) were includede in this prospective study. All patients underwent both PCT and DCE-MRI. Imaging was performed on a 256-slice CT scanner and a 3-T MRI system. PCT yielded permeability surface-area product (PS) using deconvolution physiological models; meanwhile, DCE-MRI determined volume transfer constant (K^trans) using the Tofts-Kermode compartment model. All cases were submitted to surgical intervention, and CD105-microvascular density (CD105-MVD) was measured in each glioblastoma specimen. Then, Spearman’s correlation coefficients and Bland-Altman plots were obtained for PS, K^trans and CD105-MVD. P < 0.05 was considered statistically significant.ResultsTumor PS and K^trans values were correlated with CD105-MVD (r = 0.644, P < 0.001; r = 0.683, P < 0.001). In addition, PS was correlated with K^trans in glioblastoma (r = 0.931, P < 0.001). Finally, Bland-Altman plots showed no significant differences between PS and K^trans (P = 0.063).ConclusionPCT and DCE-MRI measurements of glioblastoma perfusion biomarkers have similar results, suggesting that both techniques may have comparable utility. Therefore, PCT may serve as an alternative modality to DCE-MRI for the in vivo evaluation of glioblastoma microvasculature.     

Quantitative diffusion-weighted magnetic resonance imaging in the evaluation of parotid gland masses: a study with histopathological correlation

We evaluated the quantitative diffusion-weighted magnetic resonance imaging (DW-MRI) for parotid masses. Seventy-five patients with 81 focal parotid masses were included. Following DW-MRI, 73 masses underwent surgical biopsy/resection, 6 underwent ultrasonography-guided fine-needle aspiration, and 2 underwent both procedures. The mean apparent diffusion coefficient (ADC) of benign tumors (n= 49, 1.72×10^? 3 mm²/s) was higher than that of malignant tumors (n= 32, 1.05×10^? 3 mm²/s) (P<.001). ADC was 2.15×10^? 3 mm²/s for pleomorphic adenomas, which was higher than that for other tumors (P<.001 for all). ADC cutoff was 1.315 for distinguishing between pleomorphic adenomas and others including malignant tumors. Therefore, DW-MRI may be useful for distinguishing between pleomorphic adenomas and other parotid masses.     

Lymph node metastasis in head and neck squamous carcinoma: Efficacy of intravoxel incoherent motion magnetic resonance imaging for the differential diagnosis

PurposeTo evaluate the value of pure molecular diffusion(D), perfusion-related diffusion (D*), perfusion fraction (f) and apparent diffusion coefficient (ADC) based on intravoxel incoherent motion (IVIM) theory for differential diagnosis of metastatic lymph nodes (LNs) in head and neck squamous cell carcinoma(HNSCC).Materials and methods29 patients with HNSCC and 20 patients with lymph node hyperplasia (LNH) were enrolled in this retrospective study, underwent magnetic resonance (MR) examination. IVIM Diffusion-weighted imaging (IVIM-DWI) was performed with 13 b values. D, D*, f and ADC values were compared between two groups. The diagnostic value of ADC, D, D* and D·D* value were evaluated by Receiver operating characteristic (ROC) curve. Two radiologists measured D, D*, f and ADC values independently.Results33 malignant LNs in HNSCC group and 22 benign LNs in LNH group (minimum diameter, ≥5 mm) were successfully examined, ADC(P < 0.05), D (P < 0.01) and f (P < 0.01) were significantly lower in malignant LNs than that in benign LNs, whereas D* was significantly higher (P < 0.01). The area under the ROC curve (AUC) for D·D* was 0.983 and was larger than that for D* (0.952), D (0.78) and ADC (0.67).ConclusionOur results indicate that IVIM DWI is feasible in the diagnosis of LN metastasis. D was significantly decreased in malignant LNs reflected increased nuclear-to-cytoplasmic ratio tissue, and D* was significantly increased reflected increased blood vessel generation and parenchymal perfusion in malignant LNs.     

Allele frequencies for 15 autosomal STR loci in Fars province population,southwest of Iran

Allele frequency data at 15 short tandem repeat loci, D8S1179, D21S11, D7S820, CSF1PO, D3S1358, THO1, D13S317, D16S539, D2S1338, D19S433, VWA, TPOX, D18S51, D5S818 and FGA have been determined for unrelated individuals in a population sample of Iranian Fars individuals. With exception of the D13S317 (P-value = 0.0458) and TPOX (P-value = 0.0477), no deviation from HWE were found in the study population using the exact test. The most discriminating loci were FGA (PD = 0.965) and D2S1338 (PD = 0.964). These data can be used for estimating the frequency of short tandem repeat profiles in a population of Fars province individuals.     

Magnetic resonance diffusion tensor imaging of the testis: Preliminary observations

IntroductionTo evaluate the feasibility of testis diffusion tensor imaging (DTI), to determine normative apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values and to assess the efficacy of DTI in characterizing testicular pathology.Materials and methodsFifty-six men underwent MRI of the scrotum, including DTI. Parametric and non-parametric statistical tests were used to compare the ADC and FA between the cranial, middle and lower thirds of normal testis and between the bilateral testicular thirds. Comparison between the ADC and FA of normal testis, malignant and benign testicular lesions was performed.ResultsNo significant differences of the ADC and FA in normal testis between the cranial, middle and lower thirds and between the bilateral testicular thirds were found. ADC was significantly lower in malignancies compared to normal testis (P = 0.006) and benign testicular lesions (P = 0.006). FA was significantly higher both in malignancies (P = 0.001) and benign lesions (P < 0.001) compared to normal testis. FA in malignancies did not differ from FA in benign lesions (P = 0.221)ConclusionsThis study shows the feasibility of testis DTI. Both ADC and FA significantly differ between testicular lesions and normal testis, although FA did not show an incremental diagnostic value compared to ADC in lesion differentiation.     

Diffusion-weighted magnetic resonance imaging of head and neck squamous cell carcinomas

ObjectiveTo evaluate whether diffusion-weighted imaging (DWI) is a reliable technique to quantify microstructural differences between head and neck squamous cell carcinomas (SCC) and tumour-free soft tissue.Materials and methodsDWI was obtained from 20 patients with histologically proven, untreated head and neck SCC. DWI was acquired using a diffusion-weighted, navigated echo-planar imaging sequence with a maximum b-value of 800 s/mm². For an objective assessment of image quality, the signal-to-noise ratio (SNR) was calculated. Microstructural differences between vital tumour tissue and tumour-free soft tissue were quantified by calculating the apparent-diffusion-coefficients (ADC) on a pixel by pixel method.ResultsEcho-planar DWI provided good image quality in all patients (mean SNR 18.4). The mean ADC of SCC, (0.64 ± 0.28 × 10⁻³ mm²/s), was significantly (P < 0.0001) lower than that of the tumour-free soft tissue, (2.51 ± 0.82 × 10⁻³ mm²/s).ConclusionDWI is a reliable diagnostic tool to quantify the microstructural differences between vital tumour tissue and tumour-free soft tissue in patients with head and neck SCC.     

Uterine fibroids: Influence of “T2-Rim sign” on immediate therapeutic responses to magnetic resonance imaging-guided high-intensity focused ultrasound ablation

ObjectivesTo investigate the influence of a high-signal-intensity peripheral rim on T2-weighted MR images (i.e., T2-rim sign) on the immediate therapeutic responses of MR-guided high intensity focused ultrasound (MR-HIFU) ablation of uterine fibroids.MethodsThis retrospective study was approved by the institutional review board, and patient informed consent was obtained for MR-HIFU ablation. In total, 196 fibroids (diameter 6.2 ± 2.6 cm) in 123 women (age 43.4 ± 5.0 years) who underwent MR-HIFU ablation from January 2013 to April 2016 were included. The effects of a T2-rim sign on the immediate therapeutic responses (non-perfused volume [NPV] ratio, ablation efficiency [NPV/treatment cell volume], ablation quality [grade 1-5, poor to excellent]) were investigated with univariable and multivariable analyses using generalized estimating equation (GEE) analysis. In multivariable analysis, T2 signal intensity ratio of fibroids-to-skeletal muscle, relative peak enhancement of fibroids, and subcutaneous fat thickness were also considered.ResultsThe presence of a T2-rim sign significantly lowered the NPV ratio (54.0 ± 28.0% vs. 83.7 ± 17.7%), ablation efficiency (0.6 ± 0.5 vs. 1.3 ± 0.6), ablation quality (3.1 ± 1.2 vs. 4.2 ± 0.8), (P < 0.0001). GEE analysis showed that the presence of a T2-rim sign was independently significant for ablation efficiency and ablation quality (P < 0.05).ConclusionUterine fibroids with a T2-rim sign showed significantly poorer immediate therapeutic responses to MR-HIFU ablation.     

Bilateral difference in hamstrings to quadriceps ratio in healthy males and females

ObjectiveTo compare the isometric and isokinetic hamstrings to quadriceps (H:Q) ratio 1) between the dominant (D) and non-dominant (ND) legs, and 2) between healthy males and females.DesignCross-sectional.SettingUniversity research laboratory. Quadriceps and hamstrings strength were assessed by maximum isometric contractions at six angles (40°, 50°, 60°, 70°, 80°, 90°) and concentric contractions at three angular velocities (60° s^?1, 180° s^?1, 300° s^?1).ParticipantsForty physically active adults (25 males).Main outcome measuresPeak isometric and isokinetic torques of the quadriceps and hamstrings, and the corresponding H:Q ratios.ResultsIsometric H:Q ratio increased with greater knee extension (P < 0.001), with overall a higher ratio in the D leg (P < 0.001). Isokinetic H:Q ratio increased with angular velocity (P < 0.001), with a higher ratio in the D leg (P < 0.05). Neither isometric nor isokinetic H:Q ratios differed between males and females.ConclusionsWhen setting rehabilitation goals, it may be appropriate to adjust the H:Q ratio and leg strength based on the uninvolved leg with consideration of leg dominance. Gender-related differences do not explain the discrepancy in the literature regarding bilateral differences in the H:Q ratio. Other subject characteristics such as age and training may be more relevant.     

Contrast-enhanced MR 3D angiography in the assessment of brain AVMs

Background and purposeDigital subtraction angiography (DSA) is the current reference standard for the diagnosis, assessment, and management of brain arteriovenous malformations (AVMs). The purpose of this study was to compare the diagnostic utility of three-dimensional (3D) time-of-flight (TOF) magnetic resonance angiography (MRA) and contrast-enhanced 3D MRA in patients with intracranial arteriovenous malformations (AVMs) in different sizes and locations. The AVM diagnosis was proved via DSA and almost half of the patients had also hematoma.Materials and methodsTwo radiologists, experienced on neurovascular imaging and independent from each other, retrospectively reviewed two MRA techniques and DSA with regard to the assessment of feeding arteries, AVM nidus, and venous drainage patterns on 20 patients with 23 examinations by scoring system. Disagreements were resolved by consensus.ResultsAn excellent agreement between contrast-enhanced MRA and DSA was found in order to assess the numbers of arterial feeders and draining veins (Spearman r = 0.913, P < 0.001). The average scores in contrast-enhanced MRA for feeders, nidi, and drainers were respectively 2.26, 2.69, and 2.48, while in TOF-MRA they are 1.96, 1.35, and 0.89, respectively.ConclusionCompared to TOF-MRA, 3D contrast-enhanced MRA is useful for visualization by subtraction technique of malformation components presented by hematoma or by haem product. On the other hand, for the cases presented by slow or complex flow that is especially in around or nidi or around the venous portion is also advantageous because of the independence from flow-related enhancement. Therapeutic effects were clearly demonstrated in three follow-up patients. A major limitation of this technique is the low spatial resolution. Since there is such a limitation, arterial feeder of a case with micro-AVM is not detected by contrast-enhanced MRA and nidus for the same case was observed retrospectively. In this respect, we believe that 3D contrast-enhanced MRA is a less invasive and inexpensive angiographic tool, but not a safe substitute for DSA. Yet, it can be a benefıcıal supplement to DSA in patients with cerebral AVMs at both initial diagnosis and at follow-up processes after therapy.     

MR spectroscopy features of brain in patients with mild and severe obstructive sleep apnea syndrome

PurposeWe investigated whether there are differences in metabolite ratios of different brain regions between mild and severe obstructive sleep apnea (OSA) patients.Materials and methodsA total of 17 mild OSA and 14 severe OSA patients were enrolled. N-acetyl aspartate (NAA)/creatine (Cr), choline (Cho)/Cr and NAA/Cho ratios were calculated by using multivoxel magnetic resonance spectroscopy (MRS) (TR: 1500, TE: 135 ms) from hippocampus, putamen, insular cortex, thalamus and temporal white matter. The relationship between the two groups was evaluated with Mann–Whitney U test.ResultsNAA/Cr ratios obtained from hippocampus was found to be significantly increased in severe OSA patients compared to mild OSA patients (P= .004). Cho/Cr ratios obtained from hippocampus and putamen in severe OSA patients were significantly increased when compared to mild OSA patients (P= .003 and P= .004, respectively). In addition, NAA/Cho ratios of putamen were significantly decreased in severe OSA patients when compared to mild OSA (P= .032).ConclusionMRS identified hypoxia-related metabolite and microstructural changes in hippocampus and putamen. The metabolite changes of increase in NAA/Cr and Cho/Cr ratios and decrease in NAA/Cho ratio were more pronounced with increasing severity of OSA syndrome.     

Comparison between multi-shot gradient echo EPI and balanced SSFP in unenhanced 3T MRA of thoracic aorta in healthy volunteers

PurposeThe purpose of this study was to compare scan time and image quality between magnetic resonance angiography (MRA) of the thoracic aorta using a multi-shot gradient echo planar imaging (MSG-EPI) and MRA using balanced steady-state free precession (b-SSFP).Materials and methodsHealthy volunteers (n = 17) underwent unenhanced thoracic aorta MRA using balanced steady-state free precession (b-SSFP) and MSG-EPI sequences on a 3T MRI. The acquisition time, total scan time, signal-to-noise ratio (SNR) of the thoracic aorta, and the coefficient of variation (CV) of thoracic aorta were compared with paired t-tests. Two radiologists independently recorded the images’ contrast, noise, sharpness, artifacts, and overall quality on a 4-point scale.ResultsThe acquisition time was 36.2% shorter for MSG-EPI than b-SSFP (115.5 ± 14.4 vs 181.0 ± 14.9 s, p < 0.01). The total scan time was 40.4% shorter for MSG-EPI than b-SSFP (272 ± 78 vs 456 ± 144 s, p < 0.01). There was no significant difference in mean SNR between MSG-EPI and b-SSFP scans (17.3 ± 3.6 vs 15.2 ± 4.3, p = 0.08). The CV was significantly lower for MSG-EPI than b-SSFP (0.2 ± 0.1 vs. 0.5 ± 0.2, p < 0.01). All qualitative scores except for image noise were significantly higher in MSG-EPI than b-SSFP scans (p < 0.05).ConclusionThe MSG-EPI sequence is a promising technique for shortening scan time and yielding more homogenous image quality in MRA of thoracic aorta on 3T scanners compared with the b-SSFP.     

The value of true-FISP sequence added to conventional gadolinium-enhanced MRA of abdominal aorta and its major branches

To test true-fast imaging with steady-state precession (true-FISP) added to gadolinium-based MR angiography (Gd-MRA) for imaging abdominal aorta and major abdominal vessels, 35 consecutive patients (age 67 ± 11 years) with known or suspected abdominal and/or peripheral vascular disease were studied with sagittal and axial 2D true-FISP during free breathing and coronal 3D fast low-angle shot (FLASH) Gd-MRA (breath-holding, 0.2 mmol/kg of Gd-DOTA at 2 ml/s). We evaluated: suprarenal aorta, celiac trunk, superior mesenteric artery, right renal artery, left renal artery, infrarenal aorta, inferior mesenteric artery, aortic bifurcation/common iliac arteries, lumbar arteries and aortic atheromasia. The possible presence of accessory renal arteries, collateral vasculature and vascular prosthesis/stent was evaluated. A quality four-point score was assigned to each item on both sequences, from 0 (not visible) to 3 (good-to-excellent image quality) and Wilcoxon test was used. Main diagnoses resulted: normal or atheromasic aorta (n = 25); aortic aneurysm (n = 2); patent aorto-iliac surgical prosthesis (n = 2); patent vascular iliac stent (n = 2); aneurysm of iliac artery (n = 1); patent aortic endovascular prosthesis (n = 1); patent aorto-femural bypass (n = 1) and aorto-iliac surgical prosthesis endoleak (n = 1). We also found three patients with accessory renal arteries, two with collateral circulation, and three with surgical aorto-iliac prosthesis. The score of true-FISP (25.9 ± 4.1, median 27) was significantly higher (p = 0.003) than that of Gd-MRA (23.9 ± 3.6, median 24). True-FISP was superior for visualizing inferior mesenteric artery (score 2.5 ± 1.1 vs. 1.0 ± 1.4; p < 0.001) and atheromasic plaques (2.5 ± 1.1 vs. 1.2 ± 1.1; p < 0.001). One collateral vasculature was demonstrated only with Gd-MRA. Summarizing, true-FISP is a power and fast non-breath-hold sequence to be added to Gd-MRA, obtaining an information increase.     

Prospectively ECG-triggered high-pitch coronary CT angiography at 70 kVp with 30 mL contrast agent: An intraindividual comparison with sequential scanning at 120 kVp with 60 mL contrast agent

PurposeTo investigate image quality, radiation dose, and diagnostic efficiency of prospectively ECG-triggered high-pitch coronary CT angiography (CCTA) at 70 kVp with 30 mL contrast agent intra-individually compared with routine CCTA protocol.Materials and methodsOne hundred and thirty eight patients with suspected coronary artery disease, body mass index (BMI) ≤ 25 kg/m² and heart rate (HR) ≤ 70 beats per minute (bpm) underwent prospectively ECG-triggered high-pitch CCTA at 70 kVp and 30 mL contrast agent (protocol A) and prospectively ECG-triggered sequential scanning at 120 kVp and 60 mL contrast medium (protocol B). Objective and subjective image quality, radiation doses, and diagnostic accuracy were evaluated and compared between the two protocols.ResultsHigher CT attenuation, higher noise, lower signal-to-noise ratios (SNRs) and lower contrast-to-noise ratios (CNRs) were found in protocol A than in protocol B (P < 0.001). However, image quality of protocol A were diagnostic. In patients with BMI < 23 kg/m² or HR < 60 bpm, subjective image quality scores of some coronary arteries in protocol A were not significantly different from protocol B (P > 0.05). Effective dose in protocol A has reduced by 96.7% compared with protocol B (P < 0.001). No significant differences were found for diagnostic accuracy between the two protocols on a per-segment (P = 0.513), per-vessel (P = 0.317) and per-patient (P = 0.125) basis.ConclusionsProspectively ECG-triggered high-pitch CCTA at 70 kVp with 30 mL contrast agent can reduce radiation dose but maintain image quality and high diagnostic accuracy in a selected, non-obese population.     

Four-way-leaning test shows larger limits of stability than a circular-leaning test

IntroductionLimits of stability (LOS) have extensive clinical and rehabilitational value yet no standard consensus on measuring LOS exists. LOS measured using a leaning or a circling protocol is commonly used in research and clinical settings, however differences in protocols and reliability problems exist.ObjectiveThis study measured LOS using a four-way-leaning test and a circular-leaning test to test which showed larger LOS measurements. Furthermore, number of adaptation trials needed for consistent results was assessed.MethodLimits of stability were measured using a force plate (Metitur Good Balance System^®) sampling at 50 Hz. Thirty healthy subjects completed 30 trials assessing LOS alternating between four-way-leaning test and circular-leaning test.ResultsA main effect of methods (ANOVA:F(1,28) = 45.86, P < 0.01) with the four-way-leaning test showing larger values than the circular-leaning test (NK, P < 0.01). An interaction between method × directions was found (ANOVA:F(3, 84) = 24.87, P < 0.01). The four-way-leaning test showed larger LOS in anterior (NK, P < 0.05), right (NK, P < 0.01) and left direction (NK, P < 0.01). Analysis of LOS for the four-way-leaning test showed a difference between trials (ANOVA:F(14,392) = 7.81, P < 0.01). Differences were found between trial 1 and 7 (NK, P < 0.03), trial 6 and 8 (NK, P < 0.02) and trial 7 and 15 (NK, P < 0.02). Four-way-leaning test showed high correlation (ICC > 0.87) between first and second trial for all directions.ConclusionFour-way-leaning test yields larger LOS in anterior, right and left direction making it more reliable when measuring LOS. A learning effect was found up to the 8th trial, which suggests using 8 adaptation trials before reliable LOS is measured.     

Energy cost of walking in children with spastic cerebral palsy: Relationship with age,body composition and mobility capacity

The energy cost (EC) of walking is different for typically developing (TD) and children with cerebral palsy (CP). The associated factors of EC are not fully understood in children with CP. We assessed the relationship between EC and age, body surface area (BSA), and gross motor function measure (GMFM). We retrospectively examined data collected between 2003 and 2011 on 276 children aged 4–18 years who were classified as Gross Motor Function Classification System level I, n = 79; II, n = 123; and III, n = 74. Energy cost was assessed while children walked 6–8 min at a comfortable, self-selected speed using their typical walking aids and/or orthoses as part of a clinical gait analysis. During the test, participants wore a breath-by-breath portable gas analysis system, measuring oxygen consumption. To calculate EC (J/kg/m), oxygen consumption was converted to J/kg/min and divided by walking speed. Data were analyzed using linear regression model. Energy cost correlated inversely with age (β = −0.16, R² = 0.02, P = 0.01), BSA (β = −3.35, R² = 0.11, P < 0.0001), and GMFM (β = −0.12, R² = 0.42, P < 0.0001). In the multiple linear regression model, GMFM was the most potent correlate of EC, BSA explained another 10% of the variance (R² = 0.53), and age was a marginally significant correlate of EC (P = 0.08). In summary, in children with CP in our study, EC decreased as GMFM and BSA increased, and GMFM was the most potent correlate of EC.     

Application of arterial spin labeling perfusion MRI to differentiate benign from malignant intracranial meningiomas

PurposeDifferentiating WHO grade I–III of meningioma by non-invasive imaging is challenging. This study investigated the potential of MR arterial spin labeling (ASL) to establish tumor grade in meningioma patients.Material and methodsPseudo-continuous ASL with 3D background suppressed gradient and spin echo (GRASE) was acquired on 54 patients with newly diagnosed or recurrent intracranial meningioma. Perfusion patterns characterized in CBF color maps were independently evaluated by three neuroradiologists blinded to patient history, and correlated with tumor grade from histo-pathological review.ResultsThree perfusion patterns could be discerned by visual evaluation of CBF maps. Pattern 1 consisted of homogeneous hyper-perfusion of the entire tumor; pattern 2 demonstrated heterogeneous hyper-perfusion; pattern 3 showed no substantial hyper-perfusion. Evaluation of the perfusion patterns was highly concordant among the three readers (Kendall W = 0.9458, P < 0.0001). Pattern 1 was associated with WHO Grade I meningioma of (P < 0.0001). Patterns 2 and 3 were predictive of WHO Grade II and III meningioma (P < 0.0001), with an odds ratio (OR, versus pattern 1) of 49.6 (P < 0.01) in a univariate analysis, and an OR of 186.4 (P < 0.01) in a multivariate analysis.ConclusionQualitative evaluation of ASL CBF maps can help differentiate benign (WHO Grade I) from higher grade (WHO Grade II and III) intracranial meningiomas, potentially impacting therapeutic strategy.     

Raw-data-based iterative reconstruction versus filtered back projection: image quality of low-dose chest computed tomography examinations in 87 patients

ObjectiveThe objective was to compare standard-dose chest computed tomography (CT) reconstructed with filtered back projection (FBP) versus low-dose images with FBP and raw-data-based iterative reconstruction.MethodsEighty-seven consecutive patients (46 male; mean age, 54.54±16.12; mean body mass index, 24.58±4.07) referred for initial chest CT with full-dose examinations [mean dose–length product (DLP), 183.37±44.13 mGy·cm] and follow-up chest CT with half-dose examinations (mean DLP, 91.08±23.81 mGy·cm) were included. The full-dose protocol was reconstructed with FBP; the half-dose protocol was reconstructed with FBP and sinogram-affirmed iterative reconstruction (SAFIRE). Noise and signal-to-noise ratio were compared using a paired Student’s t test; subjective image quality and lesion conspicuity were compared using Wilcoxon signed ranks test.ResultsActual radiation dose of follow-up CT was about 50% (49.26%±2.62%) of standard-dose protocol. Compared to full-dose images with FBP, there was no significant difference in half-dose images with SAFIRE in the objective noise (ascending aorta: P= .38, descending aorta: P= .70, trachea on mediastinal images: P= .37) and SNR (ascending aorta: P= .14, descending aorta: P= .72, trachea on mediastinal images: P= .06) on mediastinal images. Noise was significantly lower (P< .001) and SNR was significantly higher (P< .001) in half-dose images with SAFIRE on lung images. Noise was significantly higher (P< .001) and SNR was significantly lower (P< .001) in half-dose images with FBP. Subjective image quality was similar on both mediastinal images (P= .317) and lung images (P= .614) of half-dose SAFIRE images versus full-dose FBP images. Lesion conspicuity was also similar. Subjective image quality was significantly lower on both mediastinal images (P< .001) and lung images (P< .001) of half-dose FBP images versus full-dose FBP images. The conspicuity of some lesions was significantly lower (ground-glass opacity, P< .0001; ill-defined micronodule, P< .0001; lung cyst, P< .0001; emphysematous lesion, P= .003) on half-dose FBP versus full-dose FBP images.ConclusionCompared to full-dose CT images reconstructed with the conventional FBP algorithm, SAFIRE with three iterations could provide similar or better image quality at 50% less dose.     

Reproducibility and accuracy of ABC/2 and 3D techniques in ICH volume measurement

PurposeThe aims of this study were to validate 3D volume measurement and to compare ICH volume determined by conventional measurements.Materials and methodsData of all 50 patients were retrospectively collected. The ICH volume was compared using ABC/2 technique and 3D volumetric technique by two observers. Interobserver and intraobserver variations were calculated. Variability of measurements was analysed.ResultsThe mean volume was 41.43 ± 3.0 mm³ using 3D technique versus 45.37 ± 3.9 mm³ using ABC/2 technique. The coefficients of variation for interobserver and intraobserver variability of 3D and ABC/2 technique were 5.03% versus 6.28% and 2.78% versus 8.77%. ABC/2 technique generally overestimated ICH volume. The 95% confidence interval (CI) of 3D and ABC/2 technique was 29.4–53.5 mm³ and 32–58.6 mm³. There was no significance difference in volume measurement by variance ratio test (F-test), where p = 0.527. The correlation coefficient of ABC/2 and 3D method was 0.99 (p < 0.001, 95% CI 0.98–0.99). Box-and-whisker graph showed that ABC/2 technique generally overestimated the ICH volume with irregular margin.The results showed that (a) ICH volumes estimated by the ABC/2 technique do not significantly differ from 3D technique. (b) ABC/2 technique was accurate when estimating volume with regular margin but overestimated volume in irregular margin. (c) Reproducibility of 3D technique in ICH volume with irregular margin was higher. (d) Reproducibility of ABC/2 technique in ICH volume with regular margin was higher.Conclusions3D technique is the most reproducible technique. Although the ABC/2 technique slightly overestimates ICH volume with irregular margin, the difference was not significant. In view of the software requirement for 3D measurement, ABC/2 technique is considered a rapid and reliable volume measurement technique.     

Altered spontaneous brain activity pattern in cognitively normal young adults carrying mutations of APP,presenilin-1/2 and APOE ε4

ObjectiveTo explore genetic effects of amyloid precursor protein (APP), presenilin-1/2 and apolipoprotein E (APOE) ε4 on brain structural and functional alterations in cognitively normal young adults.Materials and methodsEighty healthy adults (mean age 24.0 ± 2.5 years; n = 18, APP/presenilin-1/2 group; n = 31, APOE ε4 group; n = 31, control group [without above-mentioned gene mutation]) underwent high-resolution T1-weighted 3D anatomical imaging, resting-state functional MR imaging and neuropsychological assessments. We used voxel-based morphometry and regional homogeneity (ReHo) algorithms to investigate brain structural and functional changes among three groups, and performed correlation analyses between the brain regions with statistically significant difference and neuropsychological results.ResultsNo brain structural changes were found, however, ReHo values were increased in right parietal-frontal lobes in APOE ε4 group, and decreased in the left middle temporal gyrus in APP/presenilin-1/2 group compared with controls (all P < 0.05). Compared with APOE ε4 group, decreased ReHo values of bilateral temporal lobes were shown in APP/presenilin-1/2 group (P < 0.05). ReHo values of right superior frontal gyrus in APOE ε4 group positively correlated with neuropsychological tests scores(P < 0.05).ConclusionCognitively normal young adults carrying APOE ε4 or APP/presenilin-1/2 had different spontaneous brain activity patterns without cerebral structural differences.