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Objective To evaluate image quality of 3D-FIESTA-C sequence displaying lumbar spinal nerves and intervertebral discs in patients with low back pain.Methods Routine protocol for lumbar MRI examinations (sagittal IDEAL,sagittal T1 WI and axial T2 WI sequences)and sagittal 3D-FIESTA-C sequence were performed in 40 patients with low back pain.The MPR of the 3D-FIESTA-C images were used for further analysis.Two radiologists scored the different sequences of images independently.The SNR and the CNR between spinal nerves and cerebrospinal fluid were calculated at 3D-FIESTA-C,IDEAL,T2 WI sequences.Results The image scores of 3D-FIESTA-C (4.77±0.42)was higher than that of the routine protocol (3.00±0.32),and the difference was statistically significant (P＜0.0 1 ). For 3D-FIESTA-C,IDEAL and T2 WI sequences,the SNR of the spinal nerves was 33.07±12.29,39.91 ±18.16,27.40±10.34,respectively,and there was no statistical difference between 3D-FIESTA-C and IDEAL,3D-FIESTA-C was better than T2 WI (P＜0.05).The SNR of cerebrospinal fluid was 26 9.1 5 ±70.30,21 3.1 3±40.52,1 1 9.25 ±35.1 5 ,respectively,and 3D-FIESTA-C was better than IDEAL,T2 WI sequences (P＝0.000).The CNR between spinal nerves and cerebrospinal fluid was 235.92±62.04,172.69±38.75,91.85±30.62,respectively,and 3D-FIESTA-C was better than IDEAL,T2 WI sequences (P＝0.000).Conclusion The 3D-FIESTA-C sequence could display spinal nerves and the relative spatial relationship between the spinal nerves and the intervertebral discs,and addition of a 3D-FIESTA-C sequence to a routine lumbar MR protocol may be useful in patients with low back pain.
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OBJECTIVE: To compare conventional sensitivity encoding (SENSE) to compressed sensing plus SENSE (CS) for high-resolution magnetic resonance imaging (HR-MRI) of intracranial and extracranial arteries. MATERIALS AND METHODS: HR-MRI was performed in 14 healthy volunteers. Three-dimensional T1-weighted imaging (T1WI) and proton density-weighted imaging (PD) were acquired using CS or SENSE under the same total acceleration factors (AF(t))-5.5, 6.8, and 9.7 for T1WI and 3.2, 4.0, and 5.8 for PD-to achieve reduced scanning times in comparison with the original imaging sequence (SENSE T1WI, AF(t) 3.5; SENSE PD, AF(t) 2.0) using the 3-tesla system. Two neuroradiologists measured signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), and used visual scoring systems to assess image quality. Acceptable imaging was defined as a visual score ≥ 2. Repeated measures analysis of variance and Cochran's Q test were performed. RESULTS: CS yielded better image quality and vessel delineation than SENSE in T1WI with AF(t) of 5.5, 6.8, and 9.7, and in PD with AF(t) of 5.8 (p 0.05). SNR and CNR in CS were higher than they were in SENSE, but lower than they were in the original images (p < 0.05). CS yielded higher proportions of acceptable imaging than SENSE (CS T1WI with AF(t) of 6.8 and PD with AF(t) of 5.8; p < 0.0167). CONCLUSION: CS is superior to SENSE, and may be a reliable acceleration method for vessel HR-MRI using AF(t) of 5.5 for T1WI, and 3.2 and 4.0 for PD.
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Acceleration , Arteries , Healthy Volunteers , Magnetic Resonance Imaging , Methods , Protons , Signal-To-Noise RatioABSTRACT
Objective To explore the value of CT spectral imaging in the demonstration of pancreatic ductal adenocarcinoma (PDAC).Methods 113 patients were scanned by CT spectral,and gemstone spectral imaging (GSI) was performed in late arterial phase (AP) and portal venous phase (PP).All diagnosis were pathologically confirmed.The ROIs were placed on the lesion and on the pancreatic parenchyma.The ROI files including the CTmono values and the normalized CTmono values (normalized to pancreatic parenchyma) were saved.The works were performed three times repeatedly.CNR values ranged from 40 keV to 140 keV and the optimal keV in AP and PP were calculated.The differences of CTmono values, normalized CTmono values,and CNR were compared between the optimal keV and 70 keV(equivalent to conventional 120 kVp energy level).Paired t-test and Wilcoxon signed rank test were performed.P<0.05 was considered statistically significant.Results The optimal monochromatic energy of PDAC were 40 keV in both AP and PP.The optimal CNR values(mean±standard) were 2.31±1.02 and 2.38±1.02 in AP and PP,while the corresponding values of 70 keV were 2.08±0.98 and 2.12±0.96.The CNR of 40 keV was higher than that of 70 keV in both AP and PP.The CTmono values of PDAC were (58±13) HU and (71±19) HU at 70 keV and were (111±44) HU and (155±57) HU at 40 keV in AP and PP.The CTmono value in PP was higher than in AP.The median of normalized CTmono values of PDAC at 40 keV were 47.0% and 53.9% in AP and PP, and were lower than those of 70 keV,which were 57.7% and 61.8%.The differences of normalized CTmono values between 40 keV and 70 keV were significant.Conclusion CT spectral imaging manifests that PDAC is hypovascular both in AP and PP and is progressively enhanced form AP to PP.There is maximal conspicuity of tumor in AP, and the optimal monochromatic imaging can improve the conspicuity of PDAC lesion.
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Purpose: To find the optimal slice thickness (Δτ) setting for patient registration with kilovoltage cone-beam CT (kVCBCT) on the Varian On Board Imager (OBI) system by investigating the relationship of slice thickness to automatic registration accuracy and contrast-to-noise ratio. Materials and method: Automatic registration was performed on kVCBCT studies of the head and pelvis of a RANDO anthropomorphic phantom. Images were reconstructed with 1.0 ≤ Δτ (mm) ≤ 5.0 at 1.0 mm increments. The phantoms were offset by a known amount, and the suggested shifts were compared to the known shifts by calculating the residual error. A uniform cylindrical phantom with cylindrical inserts of various known CT numbers was scanned with kVCBCT at 1.0 ≤ Δτ (mm) ≤ 5.0 at increments of 0.5 mm. The contrast-to-noise ratios for the inserts were measured at each Δτ. Results: For the planning CT slice thickness used in this study, there was no significant difference in residual error below a threshold equal to the planning CT slice thickness. For Δτ > 3.0 mm, residual error increased for both the head and pelvis phantom studies. The contrast-to-noise ratio is proportional to slice thickness until Δτ = 2.5 mm. Beyond this point, the contrast-to-noise ratio was not affected by Δτ. Conclusion: Automatic registration accuracy is greatest when 1.0 ≤ Δτ (mm) ≤ 3.0 is used. Contrast-to-noise ratio is optimal for the 2.5 ≤ Δτ (mm) ≤ 5.0 range. Therefore 2.5 ≤ Δτ (mm) ≤ 3.0 is recommended for kVCBCT patient registration where the planning CT is 3.0 mm
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Objective No reports has been found to date on whether frequency compounding can improve elastographic image signal to noise ratio (SNRe) and how it affects elastogram performance.In this paper simulations investigation was carried out on transmit-side frequency compounding (TSFC)for elastography.Methods 50 mm×50 mm tissue model was simulated with two round hard inclusions of 10mm diameter uniformly distributed along the tissue central axial line,and their elasticity modulus were 10 times of the background.Then simulation of 3.5 MHz、5 MHz and 7.5 MHz probes were introduced to form compression elastography of the double-lesion model by quasi-static compression method (applied strain 1%).Then,sub-elastograms obtained by the combination of 3.5 MHz and 5 MHz,3.5 MHz and 5 MHz,3.5 MHz and 7.5 MHz were compounded,respectively.Results Before compounding,signal to noise ratio (SNRe) of the various sub-elastograms were 8.42,9.62,10.73,respectively,contrast to noise ratio (CNRe) were 11.35,14.82,18.37,respectively and axial resolutions were 9.83,9.82,9.81.After compounding elastograms,the SNRe were 11.82,13.05,19.45,CNRe were 22.31,27.63,56.12,while axial resolutions were 9.83,9.83,9.83.Conclusion Frequency compounding elastograms have higher SNRe and CNRe than any sub-elastogram before compounding and have no axial resolution loss.The TSFC can improve elastogram performance efficiently and frequency compounding for elastography enhancement is feasible.
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The purpose of this study is to compensate for susceptibility and a ferromagnetic body artifact using CFA and TGV on MR Imaging. A total of 30 patients (15 men and 15 women, mean age: 45 years) were performed on head and neck diseases. MR Unit used a 1.5T superconducting magnet (GE medical system, High Density). This study have investigated by changing with CFA and TGV (70, 90, 110, 130, 150) searching for compensation values about susceptibility and a ferromagnetic body artifact in 60 kg standards of body weight (p<0.05). As a quality results, Image qualities were obtained at different score from CFA and TGV (70, 90, 110, 130, 150=3.23+/-0.35, 4.31+/-0.02 4.23+/-0.21, 5.12+/-0.25, 7.13+/-0.72, 8.31+/-0.01, 5.21+/-0.15, 6.14+/-0.08, 5.23+/-0.72, 5.91+/-0.06, p<0.05). Absolute CNRs (TG, CNRpre, CNRpost) were acquired with (70:-1.44+/-0.11, -2.7+/-0.04, 90:-2.18+/-0.42, -4.41+/-0.43, 110:-2.89+/-0.43, -5.23+/-0.02, 130:-2.34+/-0.05, -5.26+/-0.01, 150: -2.09+/-0.08, -3.87+/-0.12, p<0.05). In conclusions, this study could be compensated for metal and flow artifacts surrounding the tissues having artifact by changing CFA and TGV.