Ailian Liu

Differential diagnosis of osteoblastic metastases from bone islands in patients with lung cancer by single-source dual-energy CT: Advantages of spectral CT imaging

OBJECTIVES To evaluate the diagnostic efficacy of spectral CT for the differentiation of osteoblastic metastases (OBMs) from bone islands (BIs) in patients with lung cancer. METHODS In 94 patients with lung cancer who underwent spectral CT, focal hyperdense lesions in vertebral bodies were diagnosed as OBMs or BIs. Regions of interest were placed within each lesion to measure the mean CT value and its standard deviation (SD) on polychromatic single-energy CT (SECT) at 140 kVp and dual-energy virtual monochromatic spectral (VMS) images. The mean bone (Dbone(wa)) and water densities (Dwa(bone)) of each lesion were also measured. The slope (k) of the spectral curve was calculated. Independent-sample t-test was used to compare those values between OBMs and BIs. Receiver operator characteristic analysis was performed to compare the area under curve (AUC) for the differentiation of OBMs from BIs. RESULTS A total of 79 OBMs and 43 BIs were confirmed. The CT and SD values on SECT at 140 kVp and VMS images at 50-130 keV, k value, and Dbone(wa) for OBMs were significantly lower than for BIs; Dwa(bone) was significantly higher for OBMs than for BIs (p<0.05 for all). The AUC for the SD value at 110 keV was the highest among those parameters. The optimal cut-off value for this differentiation was 68.6 HU for the SD value on VMS images at 110 keV with sensitivity of 93.0% and specificity of 93.3%. CONCLUSION Spectral CT is helpful for the differentiation of OBMs from BIs in patients with lung cancer, particularly using SD of the CT value on high-energy VMS images.

The Value of Nonenhanced Single-Source Dual-Energy CT for Differentiating Metastases From Adenoma in Adrenal Glands

RATIONALE AND OBJECTIVES To evaluate the value of the nonenhanced single-source dual-energy computed tomography (ssDECT) in differentiating metastases from adenomas in adrenal glands. MATERIALS AND METHODS This retrospective study was approved by our Institutional Review Board, and written informed consent was waived. One hundred twelve patients (66 men:46 women; mean age, 58 years) with 63 adrenal metastases (AMs) and 64 adrenal adenomas (AAs) underwent a plain dual-energy spectral CT imaging from August 2011 to December 2013 were included. The fat (water) density (DFa [Wa]) from the material decomposition (MD) images and CT number and effective atomic number (eff-Z) from the virtual monochromatic spectral (VMS) image sets were measured for the AMs and AAs. The spectral Hounsfield unit (HU) curve (CT number as a function of photon energy from 40 to 140 keV) was generated, and its slope (K) was calculated. The difference of these parameters between AMs and AAs was statistically compared by the Wilcoxon rank sum test. Receiver operating characteristic curve (ROC) curves were used to compare the diagnostic efficacies of these measures in the identification of AAs and AMs. The distribution of spectral HU curve was analyzed using the chi-square test in terms of its slope K: ascending (K > 0.1), straight (-0.1 ≤ K ≤ 0.1), and descending (K < -0.1). RESULTS 1) The CT number (medium, range) of metastases (50.47, 29.93 HU at 40 keV and 29.00, 9.36 HU at 140 keV) was significantly higher than that of adenomas (-0.76, 33.04 to 13.73, 18.96 HU) at each energy level from 40 to 140 keV (P < .05). 2) The fat concentration of metastases (-177.37, 296.38 mg/mL) was statistically lower than that of adenomas (126.73, 328.07 mg/mL; P < .05). 3) The eff-Z of metastases (7.76, 0.23) was significantly higher than that of adenomas (7.42, 0.32; P < .05). 4) With CT number of VMS image at 40 keV of 21.78 HU as a threshold, the sensitivity and specificity for differentiating metastases from adenomas was 92.1% and 76.6%, respectively, and the area under the ROC curve was 0.90. 5) The spectral curve types included 3.2% (2 of 63) ascending, 20.6% (13 of 63) straight, and 76.2% (48 of 63) descending for the metastases, whereas the corresponding numbers were 60.9% (39 of 64), 21.9% (14 of 64), and 17.2% (11 of 64) for the adenomas. The difference was statistically significant (X(2) = 56.63; P < .05). CONCLUSIONS The nonenhanced ssDECT enables a multiparametric approach to provide an excellent sensitivity for identifying AMs from AAs.

Differentiation of osteolytic metastases and Schmorl's nodes in cancer patients using dual-energy CT: advantage of spectral CT imaging.

PURPOSE To assess the reliability of dual-energy CT (DECT) spectral imaging for the differentiation of bone metastases (BMs) from Schmorls nodes (SNs) in the vertebrae of cancer patients. MATERIALS AND METHODS In this retrospective study, 102 cancer patients who underwent DECT (GE spectral CT Discovery CT750 HD scanner) had 110 low density vertebral lesions. Each lesion was characterized as a BM or SN, based on the typical MRI or SPECT/PET-CT findings as well as size and number change in the 6 months follow-up. The means of 140 kVp polychromatic CT values, 40-140 keV monochromatic CT values, slopes (k) of the spectral curves, bone(water) and water(bone) densities of BMs and SNs were measured and compared with independent-samples t-test. The difference values of the two lesions and their respective normal bone tissue were calculated (normal density-lesion density) and compared using independent-samples t-test. ROC curves were used to compare the diagnostic efficacies of these measures in the identification of SNs and BMs. RESULTS 110 lesions consisting of 69 BMs and 41 SNs were identified. The spectral curve patterns and slopes for BMs and SNs were different (p<0.05). The water(bone) density of BMs (1009.02 ± 59.25mg/cm(3)) was higher than that of SNs (892.00 ± 83.65 mg/cm(3)) (p<0.01) while the bone(water) density (43.57 ± 50.87 mg/cm(3)) was lower than that of SNs (174.60 ±94.61 mg/cm(3)) (p<0.01). The 40 keV CT value, k, bone(water) density and water(bone) density had a higher diagnostic efficacy for differentiating the two lesions than polychromatic CT value (p<0.05). CONCLUSIONS Dual-energy CT imaging is accurate enough for identification of osteolytic metastases and Schmorls nodes.

Detection of gallbladder stones by dual-energy spectral computed tomography imaging

AIM To evaluate the detectability of gallbladder stones by dual-energy spectral computed tomography (CT) imaging. METHODS Totally 217 patients with surgically confirmed gallbladder stones were retrospectively analyzed who underwent single-source dual-energy CT scanning from August 2011 to December 2013. Polychromatic images were acquired. And post-processing software was used to reconstruct monochromatic (40 keV and 140 keV) images, and calcium-lipid pair-wise base substance was selected to acquire calcium base images and lipid base images. The above 5 groups of images were evaluated by two radiologists separately with 10-year experience in CT image reading. In the 5 groups of images, the cases in the positive group and negative group were counted and then the detection rate was calculated. The inter-observer agreement on the scoring results was analyzed by Kappa test, and the scoring results were analyzed by Wilcoxon test, with P < 0.05 indicating that the difference was statistically significant. The stone detection results of the 5 groups of images were analyzed by χ(2) test. RESULTS There was good inter-observer agreement (κ = 0.772). In 217 patients with gallbladder stones, there was a statistically significant difference in stone visualization between spectral images (40 keV, 140 keV, calcium base and lipid base images) and polychromatic images (P < 0.05). 40 keV monochromatic images were better than 140 keV monochromatic images (4.90 ± 0.35 vs 4.53 ± 1.15, P < 0.05), and calcium base images were superior to lipid base images (4.91 ± 0.43 vs 4.77 ± 0.63, P < 0.05), but there was no statistically significant difference between 40 keV monochromatic images and calcium base images (4.90 ± 0.35 vs 4.91 ± 0.43, P > 0.05). In 217 gallbladder stone patients, there were 21, 3, 28, 5 and 12 negative stone cases in polychromatic images, 40 keV images, 140 keV images, calcium base images and lipid base images, respectively, and the differences among the five groups were statistically significant (P < 0.05). CONCLUSION Monochromatic images and base substance images have a good clinical prospect in the iso-density stone detection.

Intravoxel Incoherent Motion MR Imaging: Comparison of Diffusion and Perfusion Characteristics for Differential Diagnosis of Soft Tissue Tumors

Abstract We used intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) to explore the possibility of preoperative diagnosis of soft tissue tumors (STTs). This prospective study enrolled 23 patients. Conventional MRI and IVIM examinations were performed on a 3.0T MR imager. Eight (35%) hemangiomas, 11 (47%) benign soft tissue tumors excluding hemangiomas (BSTTEHs) and 4 soft tissue sarcomas (STSs) were assessed. The mean tumor size was about 1652.36 ± 233.66 mm2. Ten b values (0–800 s/mm2) were used to evaluate diffusion and perfusion characteristics of IVIM. IVIM parameters (ADCstandard, ADCslow, ADCfast, and f) of STTs were measured and evaluated for differentiating hemangiomas, BSTTEHs, and STSs. ADCslow and ADCfast value were different for hemangiomas, BSTTEHs, and STSs separately (P < 0.001, P < 0.001, and P = 0.001). ADCslow, cut-off value smaller than 0.93 × 10–3 mm2/s, was the best parameter to differ STSs (0.689 ± 0.173 × 10−3 mm2/s) from hemangiomas (0.933 ± 0.237 × 10−3 mm2/s) and BSTTEHs (1.156 ± 0.120 × 10−3 mm2/s) (P = 0.001). ADCslow (0.93 × 10−3 mm2/s <cut-off value <0.96 × 10−3 mm2/s) was used to distinguish hemangiomas from BSTTs. There were significant difference among hemangiomas, BSTTEHs, and STSs (P = 0.014, P = 0.036, P < 0.001). The ADCstandard, ADCfast, and f value were different (P < 0.05) for STSs (1.009 ± 0.177 × 10−3 mm2/s, 15.700 ± 1.992 × 10−3 mm2/s, 0.503 ± 0.068), hemangiomas (1.505 ± 0.226 × 10−3 mm2/s, 11.675 ± 0.456 × 10−3 mm2/s, 0.682 ± 0.060), and BSTTEHs (1.555 ± 0.176 × 10−3 mm2/s, 11.727 ± 0.686 × 10−3 mm2/s, 0.675 ± 0.054). And there was no significant difference for these 3 parameters between hemangiomas and BSTTEHs (P = 0.584, 0.907, and 0.798). IVIM may be of significant value for differential diagnosing hemangiomas, BSTTEHs, and STSs.

Diagnostic Significance of Diffusion-Weighted MRI in Renal Cancer

Background. This study aimed to investigate whether diffusion-weighted imaging (DWI) could contribute to the discrimination between benign and malignant renal cancer. Methods. We searched the PubMed electronic database for eligible studies. STATA 12.0 software was used for statistical analysis. The SMD and 95% CI were calculated. Results. Decreased ADC signal was seen in all renal cancer patients (cancer tissue versus normal tissue: SMD = 1.63 and 95% CI = 0.96~2.29, P < 0.001; cancer tissue versus benign tissue: SMD = 2.22 and 95% CI = 1.53~2.90 and P < 0.001, resp.). MRI machine type-stratified analysis showed that decreased ADC signal was found by all included MRI machine types in cancer tissues compared with benign cancer tissues (all P < 0.05). The ADC values of renal cancer patients were significantly lower than those of normal controls for all included P values (all P < 0.05), and there was a decreased ADC signal at b-500, b-600, b-1000, b-500, and 1000 gradients compared with benign cancer tissues (all P < 0.05). Conclusion. Our study concluded that decreased ADC signal presented in DWI may be essential for the differential diagnosis of renal cancer.

Use of diffusion tensor imaging in assessing superficial myometrial invasion by endometrial carcinoma: a preliminary study

Background Magnetic resonance imaging (MRI) remains the standard modality for local staging of gynecological malignancies, but it has several limitations, especially when differentiating a cancer limited to the endometrium from a cancer invading the superficial myometrium. Purpose To explore 1.5 T diffusion tensor imaging (DTI) in assessing superficial myometrial infiltration by endometrial carcinoma. Material and Methods We analyzed the sensitivity of apparent diffusion coefficient (ADC) versus fractional anisotropy (FA) in diagnosing superficial myometrial infiltration compared to DCE-MRI and T2-weighted imaging (T2WI) in 35 patients with endometrial cancer. For each patient, T2WI-DWI fusion images were generated, and five regions of interest (ROIs) were placed on corresponding DTI images. ADC and FA were calculated, and fiber tractography (FT) images for each level were obtained. ADC and FA values for the five ROIs were compared. Results In distinguishing cancerous versus non-cancerous areas within superficial myometrium, median ADC values were significantly lower (1.16 vs. 1.48, respectively; P < 0.001) and median FA values were significantly higher (0.41 vs. 0.27; P < 0.001, respectively). ADC’s versus FA’s sensitivity, specificity, PPV, NPV, and accuracy for diagnosing superficial myometrial invasion were 74.3%, 88.6%, 86.7%, 77.5%, 81.4% versus 88.6%, 97.1%, 96.9%, 89.5%, 92.9%, respectively. T2WI and DCE-MR showed a sensitivity of 80.0% and 77.1%, respectively, in diagnosing myometrial invasion. Conclusion Both ADC and FA were able to distinguish between cancerous verss non-cancerous areas within superficial myometrium (although FA was more sensitive based on AUC values). In addition, FA was superior to ADC, and more sensitive than T2WI and DCE-MR, in evaluating myometrial invasion. FT images provided visual confirmation of irregular arrangement and direction of the fibers due to proliferation of stromal cells caused by superficial myometrial invasion.

Evaluation of myocardial microcirculation using intravoxel incoherent motion imaging: Myocardial Microcirculation Evaluated by IVIM

To explore whether cardiac magnetic resonance‐intravoxel incoherent motion imaging (MR‐IVIM) is feasible for the clinical evaluation of myocardial microcirculation.

Virtual Non-Contrast Computer Tomography (CT) with Spectral CT as an Alternative to Conventional Unenhanced CT in the Assessment of Gastric Cancer

OBJECTIVE The purpose of this study was to evaluate computed tomography (CT) virtual non-contrast (VNC) spectral imaging for gastric carcinoma. MATERIALS AND METHODS Fifty-two patients with histologically proven gastric carcinomas underwent gemstone spectral imaging (GSI) including non-contrast and contrast-enhanced hepatic arterial, portal venous, and equilibrium phase acquisitions prior to surgery. VNC arterial phase (VNCa), VNC venous phase (VNCv), and VNC equilibrium phase (VNCe) images were obtained by subtracting iodine from iodine/water images. Images were analyzed with respect to image quality, gastric carcinoma-intragastric water contrast-to-noise ratio (CNR), gastric carcinoma-perigastric fat CNR, serosal invasion, and enlarged lymph nodes around the lesions. RESULTS Carcinoma-water CNR values were significantly higher in VNCa, VNCv, and VNCe images than in normal CT images (2.72, 2.60, 2.61, respectively, vs 2.35, p≤0.008). Carcinoma- perigastric fat CNR values were significantly lower in VNCa, VNCv, and VNCe images than in normal CT images (7.63, 7.49, 7.32, respectively, vs 8.48, p<0.001). There were no significant differences of carcinoma-water CNR and carcinoma-perigastric fat CNR among VNCa, VNCv, and VNCe images. There was no difference in the determination of invasion or enlarged lymph nodes between normal CT and VNCa images. CONCLUSIONS VNC arterial phase images may be a surrogate for conventional non-contrast CT images in gastric carcinoma evaluation.

Utility of R2* obtained from T2*-weighted imaging in differentiating hepatocellular carcinomas from cavernous hemangiomas of the liver.

Purpose To evaluate the feasibility of applying R2* values to differentiate hepatocellular carcinomas (HCC) from cavernous hemangiomas of the liver (CHL). Materials and Methods This retrospective study was approved by the participating Institutional Review Board and written informed consent for all subjects were obtained. Seventy-three patients with 79 pathologically identified HCCs and 65 patients with 91 clinically or pathologically identified CHLs were enrolled in this study. All subjects underwent a breath-hold multi-echo T2* weighted MR imaging on a 1.5T clinical MR scanner. R2* values from HCC and CHL groups were compared using the Mann-Whitney non-parametric U test. A cut-off value of R2* was evaluated with receiver operator characteristic (ROC) analysis. Results The mean R2* value was 23.32±12.23 Hz (95% confidence interval [CI]: 20.58 Hz, 26.06 Hz) for the HCC group, and 3.66±2.37 Hz (95% CI: 3.17 Hz, 4.15 Hz) for the CHL group. The mean R2* value for HCC was significantly higher than that of CHL (p<0.001). A threshold of 9.48 Hz for the minimum R2* value in the diagnosis of HCC resulted in a sensitivity of 96.20% (76 out of 79 patients), and a specificity of 97.80% (89 out of 91 patients). The positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy for HCC were 97.44% (76 out of 78 patients), 96.74% (89 out of 92 patients) and 97.06% (165 out of 170 patients), respectively. The AUC for differentiation between these two groups was 0.994 (95% CI: 0.980, 1.000). Conclusions R2* is a significant MRI biomarker to differentiate HCC from CHL with satisfying sensitivity and specificity.