Dong Gyu Na

Sonographic Features of Follicular Variant Papillary Thyroid Carcinomas in Comparison With Conventional Papillary Thyroid Carcinomas

Objective. The purpose of this study was to compare the sonographic features as well as the results of fine‐needle aspiration biopsy (FNAB) of follicular variant papillary thyroid carcinoma (FVPTCs) and conventional papillary thyroid carcinoma (PTCs). Methods. Forty patients with 44 FVPTCs and 59 patients with 74 conventional PTCs were enrolled in this study. The sonographic features, sonographic gradings, and FNAB results were compared between the two groups. Results. The mean nodule size of FVPTCs was larger than that of conventional PTCs (17.70 versus 10.53 mm; P < .001). Sonographic features of an ovoid‐to‐round shape (95% versus 73%), isoechogenicity (52% versus 8%), and a hypoechoic halo (25% versus 3%) were more frequent in FVPTCs than conventional PTCs (P < .001). Sonographic features of a taller‐than‐wide shape (5% versus 22%), a spiculated margin (7% versus 32%), marked hypoechogenicity (5% versus 38%), and microcalcification (7% versus 24%) were rarer in FVPTCs than conventional PTCs (P < .05). The incidence of a sonographically malignant grade was also lower in FVPTCs (48%) than conventional PTCs (81%; P < .001). A diagnosis of PTC on FNAB of FVPTCs was less common than that of conventional PTCs (28% versus 56%; P = .0393); however, a diagnosis of an indeterminate cytologic type such as atypical cells or follicular lesions in FVPTCs was higher than that in conventional PTCs (46% versus 19%; P = .0418). Conclusions. Follicular variant papillary thyroid carcinomas show a relatively larger size, more benign sonographic features, a lower incidence of a sonographically malignant grade, and a lower diagnostic rate of PTC on FNAB compared with conventional PTCs.

Diffusion-tensor imaging for glioma grading at 3-T magnetic resonance imaging: Analysis of fractional anisotropy and mean diffusivity

Purpose: To retrospectively determine whether fractional anisotropy (FA) or mean diffusivity (MD) value at 3-T diffusion-tensor imaging is different between low- and high-grade gliomas and may be useful for glioma grading. Methods: Review board approval was obtained, and informed consent was waived. Diffusion-tensor imaging was performed in 27 patients with surgically proved gliomas (19 high-grade and 8 low-grade gliomas). Fractional anisotropy and MD values were measured in 3 regions; peritumoral edema, and enhancing and nonenhancing tumor regions. We compared mean FA and MD values of nonenhancing tumor regions between low- and high-grade gliomas and compared the FA and MD values among the 3 mentioned regions in high-grade gliomas. The relationship between FA and MD values of tumors was also investigated. Statistical analysis was performed using the Student t test and Pearson correlation coefficients. Results: In the nonenhancing regions of tumors, FA ratios were not significantly different between low- and high-grade gliomas (0.472 and 0.701, P = 0.075), but MD ratios were significantly lower in high-grade gliomas (1.899 and 1.23, P < 0.001). In high-grade gliomas, enhancing tumors showed a tendency toward a lower FA ratio than nonenhancing tumors (P = 0.034), but FA values or ratios of peritumoral edema were not significantly different from those of enhancing or nonenhancing tumor. No strong relationship was found between FA and MD values. Conclusions: Fractional anisotropy values of low- and high-grade gliomas were not significantly different. However, MD values of nonenhancing low-grade gliomas were significantly higher than those of nonenhancing high-grade gliomas, which will be useful for the grading of nonenhancing infiltrative gliomas.

Thyroid follicular neoplasms: Can sonography distinguish between adenomas and carcinomas?

The purpose of this study was to determine whether sonography (US) can usefully differentiate thyroid follicular adenoma (FA) and follicular carcinoma (FC).

Comparison of 1.5T and 3T 1H MR Spectroscopy for Human Brain Tumors

Objective We wanted to estimate the practical improvements of 3T proton MR spectroscopy (1H MRS) as compared with 1.5T 1H MRS for the evaluation of human brain tumors. Materials and Methods Single voxel 1H MRS was performed at both 1.5T and 3T in 13 patients suffering with brain tumors. Using the same data acquisition parameters at both field strengths, the 1H MRS spectra were obtained with a short echo time (TE) (35 msec) and an intermediate TE (144 msec) with the voxel size ranging from 2.0 cm3 to 8.7 cm3. The signal to noise ratios (SNRs) of the metabolites (myoinositol [MI], choline compounds [Cho], creatine/phosphocreatine [Cr], N-acetyl-aspartate [NAA], lipid and lactate [LL]) and the metabolite ratios of MI/Cr, Cho/Cr, Cho/NAA and LL/Cr were compared at both TEs between the two field strengths in each brain tumor. The degrees of spectral resolution between the Cho and Cr peaks were qualitatively compared between the two field strengths in each brain tumor. Results The SNRs of the metabolites at 3T demonstrated 49-73% increase at a short TE (p < 0.01) and only 2-12% increase at an intermediate TE (p > 0.05) compared with those of 1.5T. The SNR of inverted lactate at an intermediate TE decreased down to 49% with poorer inversion at 3T (p < 0.05). There was no significant difference in the metabolite ratios between the two field strengths. The degrees of the spectral resolution at 3T were slightly superior to those of 1.5T at a short TE. Conclusion As compared with 1.5T, 3T 1H MRS demonstrated 49-73% SNR increase in the cerebral metabolites and slightly superior spectral resolution only at a short TE, but little at an intermediate TE, in the brain tumors. There was no significant difference in the metabolite ratios between the two field strengths.

Detection of metastatic cervical lymph nodes in recurrent papillary thyroid carcinoma: computed tomography versus positron emission tomography-computed tomography.

Objective: We sought to determine whether positron emission tomography-computed tomography (PET-CT) is more accurate than CT for detecting metastatic cervical lymph nodes in recurrent papillary thyroid carcinoma (PTC) and to determine the relationship between the CT features and PET-CT findings of metastatic nodes. Methods: Eleven consecutive patients with recurrent PTC underwent contrast-enhanced CT (CECT) and PET-CT before surgery. We retrospectively evaluated CECT and PET-CT images to determine the presence of metastatic nodes by level-by-level analysis. The CT findings of the PET-CT results that were positive and negative for metastatic nodes were compared. Results: Metastatic nodes were found at 28 (78%) of 36 neck levels surgically explored. The sensitivity, specificity, and accuracy of CECT for the detection of metastatic nodes were 75.0%, 87.5%, and 77.8%, respectively, and those of PET-CT were 35.7%, 87.5%, and 48.6%, respectively, by level-by-level analysis. No significant difference in the CT features was found between the PET-CT findings positive and negative for metastatic nodes (P > 0.05). Conclusions: Computed tomography is more sensitive and accurate than PET-CT for detecting metastatic lymph nodes in recurrent PTC. No significant relationship was found between the CT features and the PET-CT findings of the metastatic nodes.

Review of the Current Status of Intra-Arterial Thrombolysis for Treating Acute Cerebral Infarction: a Retrospective Analysis of the Data from Multiple Centers in Korea

Objective The purpose of the study was to review the current status of intra-arterial (IA) thrombolysis in Korea by conducting a retrospective analysis of the data from multiple domestic centers. Materials and Methods The radiologists at each participating institution were asked to fill out case report forms on all patients who had undergone IA recanalization due to acute anterior circulation ischemia. These forms included clinical, imaging and procedure-related information. A central reader analyzed the CT/MR and angiographic results. The rates of successful recanalization, hemorrhagic transformation and functional outcome were obtained. The univariate analyses were performed together with the multivariate analysis. Results We analyzed the data from 163 patients, and they had been treated at seven institutes. The initial imaging modalities were CT for 46 patients (28%), MR for 63 (39%), and both for 54 (33%). Various mechanical treatment methods were applied together in 50% of the patients. Radiologically significant hemorrhage was noted in 20/155 patients (13%). We found various factors that influenced the recanalization rate and the occurrence of significant hemorrhagic transformations. The favorable outcome rate, reported as modified Rankin Scale ≤ 2, was 40%, and the mortality rate was 11%. The factors that predicted a poor functional outcome were old age (p = 0.01), initially severe neurological symptoms (p < 0.0001), MR findings of a wide distribution of lesions (p = 0.001), involvement of the basal ganglia (p = 0.01), performance of procedures after working hours (p = 0.01), failure of recanalization (p = 0.003), contrast extravasation after the procedure (p = 0.007) and significant hemorrhagic transformation (p = 0.002). The subsequent multivariate analysis failed to show any statistically significant variable. Conclusion There was a trend toward increased dependency on MR imaging during the initial evaluation and increased usage of combined pharmacologic/mechanical thrombolysis. The imaging and clinical outcome results of this study were comparable to those of the previous major thrombolytic trials.

Ultrasonography in Diagnosis and Management of Thyroid Cancer: Current International Recommendations

The rate of detection of thyroid carcinoma has increased with the widespread use of ultrasonography (US). The role of US has become increasingly important for assessing malignancy risk, fine-needle aspiration (FNA) decision, and management decision after FNA in patients with thyroid nodules. US also has an important role in preoperative staging and postoperative surveillance in patients with thyroid cancer. Many international society guidelines have been recently updated for a more personalized management strategy. Most international society guidelines propose risk stratification systems based on US patterns of thyroid nodules. Although they have similar US criteria and size cutoff for FNA, there are some differences in the sensitivity and specificity of FNA criteria for the diagnosis of thyroid cancer. The clinically feasible and accurate US risk stratification system needs to be standardized in the future. Most current international guidelines suggest more potentiated roles of US in the management of thyroid nodules after FNA, and agree that US has an essential role in preoperative staging and postoperative surveillance in patients with thyroid cancer.