Differentiating between malignant and benign solid solitary pulmonary lesions: are intravoxel incoherent motion and diffusion kurtosis imaging superior to conventional diffusion-weighted imaging?

OBJECTIVE: To quantitatively compare the diagnostic values of various diffusion parameters obtained from mono- and biexponential diffusion-weighted imaging (DWI) models and diffusion kurtosis imaging (DKI) in differentiating between benign and malignant solitary pulmonary lesions (SPLs). METHODS: Multiple b-value DWIs and DKIs were performed in 89 patients with SPL by using a 3-T magnetic resonance (MR) imaging unit. The apparent diffusion coefficient (ADC) of various b-value sets, true diffusivity (D), pseudo-diffusion coefficient (D*), perfusion fraction (f), apparent diffusional kurtosis (Kapp), and kurtosis-corrected diffusion coefficient (Dapp) were calculated and compared between the malignant and benign groups using a Mann-Whitney U test. Receiver-operating characteristic analysis was performed for all parameters. RESULT: The ADC(0, 150) values of malignant tumors were lower than those of the benign group (p = 0.01). The ADC(0, 300), ADC(0, 500), ADC(0, 600), ADC(0, 800), ADC(0, 1000), ADCtotal, D, and Dapp of malignant tumors were significantly lower than those of benign lesions (all p < 0.001). D*, f, and Kapp showed no statistically significant differences between the two groups. ADCtotal showed the highest area under the curve (AUC = 0.862), followed by ADC(0, 800)(AUC = 0.844), ADC(0, 600)(AUC = 0.843), D(AUC = 0.834), ADC(0, 1000)(AUC = 0.834) and ADC(0, 500)(AUC = 0.824), Dapp(AUC = 0.796), and ADC(0, 300) (AUC = 0.773). However, the difference in diagnostic efficacy among these parameters was not statistically significant (p > 0.05). CONCLUSION: Intravoxel incoherent motion (IVIM) and DKI-derived parameters have similar performance compared with conventional ADC in differentiating SPLs. KEY POINTS: • Mono- and biexponential DWI and DKI are feasible for differentiating SPLs. • ADC (0, ≥500) has better performance than ADC (0, <500) in assessing SPLs. • IVIM and DKI have similar performance compared with conventional DWI in differentiating SPLs.

Evaluation of radiation-induced peripheral nerve injury in rabbits with MR neurography using diffusion tensor imaging and T2 measurements: Correlation with histological and functional changes.

PURPOSE: To investigate the potential of diffusion tensor imaging (DTI) and T2 measurements in the evaluation of radiation-induced peripheral nerve injury (RIPNI). MATERIALS AND METHODS: RIPNI was produced in a randomly selected side of sciatic nerve in each of 21 rabbits while the contralateral side served as the control. The limb function and MR parameters were evaluated over a 4-month period. Fractional anisotropy (FA), axial diffusivity (λ∥ ), radial diffusivity (λ⊥ ) and T2 values were obtained using 3T MR for quantitative analysis. Two animals were randomly killed for histological evaluation at each timepoint. RESULTS: The T2 value of irradiated nerve increased at 1 day (63.95 ± 15.60, P = 0.012) and was restored at 1 month (52.34 ± 5.38, P = 0.105). It increased progressively at 2 to 4 months (60.39 ± 10.60, 66.96 ± 6.08, 75.51 ± 7.39, all P < 0.01). λ⊥ significantly increased at 1 day (0.82 ± 0.44, P = 0.046) and slightly decreased at 1 month (0.61 ± 0.17, P < 0.001). It increased gradually from 2 to 3 months (0.84 ± 0.29, 1.13 ± 0.33, both P < 0.001) followed by a decline at 4 months (0.83 ± 0.17, P < 0.001). FA was statistically lower than the contralateral sides at 1 to 4 months (0.72 ± 0.08, 0.60 ± 0.12, 0.51 ± 0.11, 0.62 ± 0.06, all P < 0.01). Changes in FA and λ⊥ correlated well with the functional and pathological changes in irradiated nerve. CONCLUSION: DTI may be a more sensitive and accurate method to evaluate RIPNI compared with T2 measurements. FA and λ⊥ are promising quantitative indices in monitoring RIPNI. J. Magn. Reson. Imaging 2016;43:1492-1499.

Development of a Rabbit Model of Radiation-Induced Sciatic Nerve Injury: In Vivo Evaluation Using T2 Relaxation Time Measurements.

OBJECTIVES: To develop a rabbit model of radiation-induced sciatic nerve injury (RISNI), using computed tomography (CT)-guided stereotactic radiosurgery, and assess the value of T2 measurements of injured nerves. MATERIALS AND METHODS: Twenty New Zealand rabbits were randomly divided into A (n = 5) and B (n = 15) groups. Group A rabbits underwent CT and magnetic resonance scan and were then killed for comparison of images and anatomy of sciatic nerves. One side of the sciatic nerve of group B rabbits received irradiation doses of 35, 50, or 70 Gy (n = 5 per group). Magnetic resonance imaging and functional assessments were performed before irradiation and 1, 2, 3, and 4 months thereafter. RESULT: The thigh section of the sciatic nerve outside the pelvis could be observed by CT and magnetic resonance imaging. T2 values of the irradiated nerve of the 35-Gy group increased gradually, peaking at 4 months; T2 values of the 50-Gy group increased faster, peaking at 3 months. Significant differences between the 35-Gy and control groups were found at 3 and 4 months, and between the 50-Gy and control groups at 2, 3, and 4 months. Functional scores of the 50-Gy group declined progressively, whereas the 35-Gy group scores reached a low point at 3 months posttreatment and then recovered. Functional scores of the irradiated limbs demonstrated a negative correlation with T2 values (r = -0.591 and -0.595, P < 0.05). Electron microscopy revealed progressive deformation and degeneration of the irradiated nerve in the 35- and 50-Gy groups, which were more severe in the 50-Gy group. CONCLUSIONS: A rabbit RISNI model can be produced using the midthigh segment of the sciatic nerve and single-fraction doses of 35 and 50 Gy. Although T2 values are useful for monitoring RISNI, they may not be sensitive enough to evaluate its severity.

Value of (18)F-FDG PET/CT and MRI in diagnosing primary endometrial small cell carcinoma.

Primary small cell carcinoma (SCC) is a group of aggressive neoplasms that mainly arise from the lung and digestive tract. Endometrial small cell carcinoma (ESCC) is extremely rare. To our knowledge, less than 90 cases have been reported, and most of these reports were dedicated to describing the clinicopathologic or immunochemical features of ESCC. Herein, we present a new case of ESCC involving a 51-year-old woman and mainly focus on the magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT) findings. MRI showed that the uterus was significantly enlarged (11.6 cm × 11.1 cm × 14.4 cm), and a giant irregular mass (7.5 cm × 8.4 cm × 8.5 cm) was observed in the uterine cavity. The lesion demonstrated an extremely low apparent diffusion coefficient (ADC) value [(0.553±0.088)×10(-3) mm(2)/s] and a high FDG uptake value (22.7). Multiple metastatic lymph nodes (LNs) were identified at different positions, with diameters ranging from 0.3 to 2.8 cm and a maximum standardized uptake value (SUVmax) ranging from 6.9 to 19.3.

Epithelioid hemangioendothelioma of right innominate vein mimics a teratoma: A case report.

RATIONAL: Epithelioid hemangioendothelioma (EHE) is a rare neoplasm commonly known to arise from the soft tissue, lung, and liver. EHE arising from right innominate vein (RIV) has scarcely been reported in English literature. PATIENT CONCERNS: Herein, we present a rare case of EHE of RIV in a 51-year-old woman with right-lower chest pain for 4 days. Computed tomography of the chest revealed a spherical mass with calcification and fatty foci located in the anterior mediastinum, thus a presumptive diagnosis of teratoma was made. DIAGNOSES, INTERVENTIONS, AND OUTCOMES: Video-assisted thoracoscopic explorations and resection of mediastinal tumor were then performed. The pathological examination showed that the tumor was EHE. Postoperative radiotherapy was delivered to the patient. Pulmonary metastases were found by chest CT a year after surgery. LESSONS: A diagnosis of EHE might be considered, when a mediastinal tumor closely related to veins showing intratumoral calcification and obvious enhancement, despite the presence of a clear boundary and visible fat content.

Intravoxel incoherent motion diffusion-weighted MR imaging in assessing and characterizing solitary pulmonary lesions.

This study aimed to investigate the potential of intravoxel incoherent motion (IVIM) diffusion-weighted MR imaging in assessing solitary pulmonary lesions (SPLs). Sixty-two patients with pathologically confirmed SPLs, including 51 and 11 cases of malignant and benign lesions, respectively, were assessed. Diffusion weighted imaging (DWI) with 13 b values was used to derive apparent diffusion coefficient (ADC) and IVIM parameters, including true diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f). Our results showed that, there was an excellent inter-observer agreement on the measurements of D and ADC between observers (inter-class correlation coefficient, ICC = 0.902 and 0.884, respectively). Meanwhile, f and D* showed good and substantial reproducibility (ICC = 0.787 and 0.623, respectively). D and ADC of malignant lesions were significantly lower than those of benign lesions (both P ≤ 0.001), while similar values were obtained in both groups for D* and f (both P > 0.05). In receiver operating characteristic (ROC) analysis, D showed the highest area under curve (AUC) for distinguishing malignant from benign lesions, followed by ADC. Accompanying signs of SPLs have specific features on IVIM maps. In conclusion, IVIM provides functional information in characterizing SPLs which is helpful to differential diagnosis. D and ADC have a significantly higher diagnostic value than f and D*.