Diagnostic accuracy of single-source dual-energy computed tomography and ultrasonography for detection of lateral cervical lymph node metastases of papillary thyroid carcinoma.

BACKGROUND: Dual-energy computed tomography (DECT) imaging can generate iodine-based material decomposition (MD) images and spectral HU curve. This study aimed to investigate the diagnostic accuracy of single-source dual-energy CT (DECT) and ultrasonography (US) for detecting lateral cervical lymph node metastases of papillary thyroid carcinoma (PTC). METHODS: Thirty patients with PTC were enrolled in the study and underwent DECT and US examination before thyroidectomy and cervical lymph node dissection. The spectral parameters included iodine concentration (IC), normalized iodine concentration (NIC) and slope (λHU) of lymph nodes. The CT morphological parameters included maximal short diameter, shape, margin, calcification and cystic degeneration of lymph nodes. The US morphological parameters included maximal short diameter, calcification and cystic degeneration of lymph nodes. The diagnostic value of every single spectral parameter, combined gemstone spectral image (GSI) parameters, CT morphological parameters and US morphological parameters between metastatic and non-metastatic lymph nodes were statistically compared. Receiver operating characteristic (ROC) curves, sensitivity, and specificity were used to determine the diagnostic value. RESULTS: Ninety-nine lymph nodes from thirty patients were pathologically confirmed. Among them, 70 (70.7%) were metastatic. For single GSI parameters, ROC analysis showed that the area under the curve (AUC) for IC was the highest (AUC =0.937) but the difference was not statistically significant when compared with NIC or slope (λHU) (P>0.05). The optimal diagnostic threshold for IC was 2.56 mg/mL, with a sensitivity, specificity and accuracy of 87.1%, 93.1%, and 88.9%, respectively. The AUC for combined GSI parameter (AUC =0.942) was higher compared with the US morphological parameters (AUC =0.771, P<0.001), with a sensitivity, specificity, and accuracy of 92.9%, 86.2%, and 90.9%, respectively. However AUC did not differ significantly among combined GSI parameters, combined CT morphological parameters and a single application for spectral CT parameters IC (P>0.05). CONCLUSIONS: Combined GSI parameters showed better diagnostic accuracy in lateral cervical lymph node metastasis of PTC compared with that of combined US morphological parameters. IC alone showed excellent diagnostic stability and could be performed easily.

Diagnostic value of single-source dual-energy spectral computed tomography for papillary thyroid microcarcinomas.

BACKGROUND: Ultrasound (US) and computed tomography (CT) are common diagnostic imaging methods for detecting and diagnosing papillary thyroid microcarcinoma (PTMC). However, single-source dual-energy spectral computed tomography (spectral CT) reduces beam hardening artefacts and optimizes contrast, which may add value in detecting PTMC. OBJECTIVE: To investigate values of applying single-source dual-energy spectral CT for diagnosing PTMCs, in comparison with high frequency ultrasound and conventional polychromatic images. METHODS: Thirty-one patients with suspected PTMC underwent contrast-enhanced dual-energy spectral CT. The images were analyzed by two experienced radiologists. Noise and contrast-noise-ratio (CNR) were compared between conventional CT and spectral CT. Ultrasonography was also performed by an experienced radiologist with a 7 to 12-MHz linear array transducer. Detection and diagnostic sensitivity were determined and compared. RESULTS: Forty-six pathologically-confirmed PTMC lesions were detected in 31 patients. Spectral CT had lower noise and higher CNR than conventional CT (P < 0.05). US detected more tumors (45/46 [97.8%] than conventional CT images (40/46 [87.0%]) or spectral CT images (44/46 [95.7%]). Among them, 30 (65.2%), 36 (78.3%), and 40 (87.0%) lesions were diagnosed correctly by conventional CT, spectral CT and US, respectively. Spectral CT had higher sensitivity than conventional CT (P = 0.031). However, there was no significant difference between spectral CT and US diagnostic sensitivities (P = 0.125). CONCLUSION: Single-source dual-energy spectral CT was superior to conventional polychromatic images and similar to high frequency ultrasound in detecting and diagnosing for PTMCs. CT had advantages in detecting level VI and VII lymph nodes. Spectral CT and US provided good results for PTMC, and aid preoperative diagnosis.

Soft-tissue osteoma in the neck paravertebral space.

Osteoma is a rare, slow-growing benign neoplasm located primarily in the skeleton. Soft-tissue osteoma is exceedingly rare. We report a case of soft-tissue osteoma occurring in the neck paravertebral space in a 25-year-old man. CT examination demonstrated a cancellous densely ossified mass in the right side of neck paravertebral space, with irregular lobulation and clear margin, but without relation to the adjacent vertebrae. The mass was resected, and the pathology confirmed soft-tissue osteoma.

Post-radiation CT changes and recurrent nasopharyngeal carcinoma.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is endemic in Southern Asia. Radiation therapy remains the mainstay of treatment strategies for NPC. Although approximately 19% - 56% of patients develop a recurrent disease 5 years after their primary treatment, recognition of post-radiation changes and early detection of relapse are important in improving the outcome of NPC. Our aim was to analyze the post-radiation changes and recurrent diseases related to NPC using computed tomography (CT) scans and to investigate their relationship. METHODS: CT scans of 510 pathologically proven NPC patients who have been followed up for more than 2 years after radiation were reviewed. The tumor's response to the radiation therapy and its relevance to recurrence were evaluated. RESULTS: For patients who were followed up for more than 2 years, their CT scans-obtained within 3 months, during the 4th to the 6th month, and beyond 7 months after radiation therapy, showed a normal nasopharyngeal cavity with a slight thickening in the wall in 93.5%, 95.0% and 84.8% of the patients respectively. The degree of tumor regression had no significant relevance to the risk of recurrence within the initial 3 months (P = 0.094). During this term, the relapse rates in the cases in which the nasopharyngeal walls were displayed as normal, slightly or moderately thickening, or with obvious residual masses on CT scans were 7.1%, 11.7%, 23.5% and 23.1% respectively. The degree of tumor regression beyond 3 months after radiation therapy had a considerable reverse relevance to the risk of recurrence (P = 0.000). The relapse rates were 13.2%, 14.1%, 10.2% and 2.1%, respectively, in the cases with a normal and a slightly thickening nasopharyngeal wall during the 4th to the 6th month, the 7th to the 12th month, the 13th to the 24th month, and beyond 25 months after radiation. In contrast, the percents in cases with moderate or more aggressive thickening walls in the corresponding periods were 62.5%, 88.9%, 100% and 100%. Within 6 months after radiation therapy, shown by CT scans, the metastatic lymph nodes disappeared, markedly decreased, slightly decreased, or enlarged in 37.4%, 51.8%, 4.7%, and 0.4%, respectively, of the patients. During 6 to 12 months after radiation therapy, the proportions were 78.5%, 19.2%, 0.6% and 1.7% correspondingly. Beyond 12 months, the proportions were 83.7%, 7.9%, 0%, and 8.4%. The regression degree of the malignant nodes after radiation therapy showed a remarkable reverse relevance to the risk of recurrence in lymph nodes (P = 0.000). In the cases with disappearing, markedly decreased, slightly decreased, or enlarged malignant nodes within six months after radiation, the relapse rates were 2.9%, 4.5%, 12.5% and 100%, respectively. CONCLUSIONS: If the nasopharyngeal walls are shown to remain moderately thick on a CT scan beyond 6 months after radiotherapy, the risk of relapse will increase. The baseline images taken within 3 months after radiotherapy and regular follow-up studies are the key to pick up the tumor recurrences in an earlier stage.

[Value of multi-slice helical CT in the diagnosis and differential diagnosis of thyroid lesions].

OBJECTIVE: To investigate the value of multi-slice helical CT in the differentiation of benign from malignant thyroid lesions. METHODS: The multi-slice helical CT images of 72 patients with 82 thyroid lesions were prospectively studied. The CT features including the margin, density of the lesion and cervical lymph node enlargement were evaluated double-blindly. All the image findings were compared with the pathological results, and analyzed statistically using the Chi-square test. RESULTS: Of 42 benign lesions, 38 (90.5 % ) showed well-defined margin, 13 (30. 9% ) contained low density nodular areas, 3 (7. 1% ) showed granular calcifications, and 2 (4. 8% ) had cervical lymph node enlargement. Of 40 thyroid carcinomas, 37 lesions(92.5% ) had irregular border, no lesion contained low density nodular areas, 14 (35. 0%) showed granular calcifications, and 31 (77. 5% ) had enlarged cervical lymph nodes. Nineteen lesions (55. 9% ) from 34 thyroid carcinoma patients who had undergone contrast enhanced CT scan showed complex density, while only 2(6. 3% ) of 32 benign lesions showed such findings on contrast enhancement. There were statistically significant differences between benign and malignant lesion in margin, low density nodular area, granular calcification, cervical lymph node enlargement and complex density( P <0.01). CONCLUSION: The findings of well-defined margin and low density nodular area in CT image may suggest benign thyroid lesions, whereas the presence of irregular border, granular calcifications and cervical lymph node enlargement as well as complex density may indicate thyroid malignancy.