MRI features of retronasopharyngeal space / 中国医学影像技术

Objective: To investigate the value of MRI in displaying posterior wall of nasopharynx. Methods: Plain MR scanning were performed in volunteers without head and neck lesions, including axial T1W and high-resolution T2W, and MRI manifestations of the posterior wall of nasopharynx were observed. Five formalin-fixed head and neck of adult cadavers were first evaluated with MRI, and then were frozen, cut into cross-section and stained with HE. The manifestations of the posterior wall of nasopharynx were observed contrastively with MRI and microscopic examination. Results: At the upper level of nasopharynx, the posterior wall of nasopharynx consisted of nasopharyngeal mucosa, fascia, prevertebral muscle and clivus from the outside. The heterogeneous signal was detected in bilateral prevertebral muscle, which was unable to clearly distinguish the posterior boundary of bilateral prevertebral muscles from the basilar clivus. Bilateral anterior edge of the prevertebral muscle was smooth and continuous low signal fascia shadow by gross observation, which was the fascia layer that consisted of the pharyngobasilar fascia, buccopharyngeal fascia, alar fascia and prevertebral fascia at the microscopic level. At the lower 1/2 level of nasopharynx, homogeneous signal was detected in bilateral prevertebral muscles, and the anterior edge was smooth while the shadow of the fascia was ambiguous, where the fibrous membranes of the pharyngeal constrictor turned thin distinctly and the pharyngeal constrictor separated it from the posterior fascia (consisted of buccopharyngeal fascia, alar fascia and prevertebral fascia) at the microscopic level. Furthermore, there was a high signal of the fat strip between posterior edge of bilateral prevertebral muscles and the lower clivus. Conclusion: MRI can clearly show the structures of fascia, prevertebral muscles and fat space in the posterior wall of nasopharynx.

Manifestations of cerebral developmental venous anomalies and its associated lesions in MRI / 中国医学影像技术

Objective To evaluate the application value of different MR sequences in cerebral developmental venous anomalies (DAVs),and to explore the relationship between DVAs and its associated lesions.Methods MRI findings in 38 patients of DAVs were analyzed retrospectively.Imaging performance and characteristics of DAVs and its associated lesions in different MR sequences were analyzed.Results In all of the 38 cases,3 cases were multiple DVAs without associated lesions,1 case was combined right lateral ventricle hemorhage,1 case was combined with multiple cavernous hemangioma,8 cases were single DVAs with solitary cavernous hemangioma,5 cases were combined with astrocytoma,1 case was combined with intracranial hematoma,and 19 cases were single DVAs with no comorbidity.DVAs in 16 cases showed strip or small patchy hypo-intensity lesions and 15 cases were not visible on T1WI;16 cases showed strip or small patchy hypo-intensity,5 cases showed strip or flocculent hypo-intensity and 10 cases could not seen on T2WI;19 cases showed patchy or strip hypo-intensity and 8 cases showed iso intensive signal on DWI;8 of the 10 cases who performed susceptibility weighted imaging (SWI) examination showed dendritic low signal,showing a typical caput medusae sign,2 cases showed no lesions on SWI;30 cases underwent 3D-T1WI enhanced scan showed clearly all lesions of DAVs,19 cases of them showed typical caput medusae sign and large draining veins.Conclusion Routine MR sequence can demonstrate part of the DVAs and associated peripheral lesions,DWI showed lesions of DAVs is superior to routine MR sequence,SWI and enhanced 3D-T1WI can accurately diagnose DVAs and show the venous drainage.

The evaluation of perfusion CT imaging in thyroid nodule / 中华放射学杂志

ObjectiveTo investigate the value of perfusion CT imaging in thyroid nodule. Methods Of the 40 cases of post-surgical thyroid nodule identified by pathology, nodular goiter was verified in 22 cases, thyroid adenoma in 6 cases,and thyroid carcinoma in 12 cases. All cases underwent CT perfusion scan at preoperative. The perfusion parameters including the blood flow ( BF), blood volume ( BV ), mean transit time ( MTT), and permeability of surface (PS) of region of interest (ROI) were calculated. The Mann-whitney test was used to comparing the differences of the different perfusion parameters. The ones with statistical significance would be introduced into the discriminatory analysis to distinguish the benign and malignant thyroid nodule. ResultsThe median MTT in 28 cases with benign thyroid nodule were 4. 33 s (Min 1.42 s,Max 10. 93 s), and that in 12 cases with malignant nodules were 2. 18 s( Min 1. 95 s, Max 2. 87 s). The difference had statistical significance ( P ＝ 0. 00 ) . The median BF in cases with thyroid carcinoma was 560. 23( Min 330. 66, Max 1000.00) ml ·100 g-1 ·min-1, and that in cases with the benign nodular were 374.79(Min 117.47,Max 1000.00) ml · 100 g-1 · min-1. There was a significant statistical difference ( P ＝0. 01 ). Through the discriminatory analysis, the difference of MTT between benign and malignant nodules were statistically significant (P ＝ 0. 00 ).After establing the Bayes discriminatory function, the overall diagnostic accuracy was 87.5％ (35/40).Conclusions MTT and BF are useful parameters in CT perfusion imaging to distinguish the benign and malignant thyroid nodules and the MTT is more accuracy.