The preoperative exclusion of thyroid carcinoma in multinodular goiter: Dynamic contrast-enhanced magnetic resonance imaging versus ultrasonography-guided fine-needle aspiration biopsy

Role of advanced MRI sequences for thyroid lesions assessment. A narrative review

Despite not being the first imaging modality for thyroid gland assessment, Magnetic Resonance Imaging (MRI), thanks to its optimal tissue contrast and spatial resolution, has provided some advancements in detecting and characterizing thyroid abnormalities. Recent research has been focused on improving MRI sequences and employing advanced techniques for a more comprehensive understanding of thyroid pathology. Although not yet standard practice, advanced MRI sequences have shown high accuracy in preliminary studies, correlating well with histopathological results. They particularly show promise in determining malignancy risk in thyroid lesions, which may reduce the need for invasive procedures like biopsies. In this line, functional MRI sequences like Diffusion Weighted Imaging (DWI), Dynamic Contrast-Enhanced MRI (DCE-MRI), and Arterial Spin Labeling (ASL) have demonstrated their potential usefulness in evaluating both diffuse thyroid conditions and focal lesions. Multicompartmental DWI models, such as Intravoxel Incoherent Motion (IVIM) and Diffusion Kurtosis Imaging (DKI), and novel methods like Amide Proton Transfer (APT) imaging or artificial intelligence (AI)-based analyses are being explored for their potential valuable insights into thyroid diseases. This manuscript reviews the critical physical principles and technical requirements for optimal functional MRI sequences of the thyroid and assesses the clinical utility of each technique. It also considers future prospects in the context of advanced MR thyroid imaging and analyzes the current role of advanced MRI sequences in routine practice.

Lymph node metastasis around the entrance point to recurrent laryngeal nerve in papillary thyroid carcinoma

There are few reports on the lymph nodes of entrance point to recurrent laryngeal nerve (LN-epRLN) in patients with papillary thyroid carcinoma (PTC). Thus, we investigated the clinical significance of LN-epRLN and implications it may have. An observational analysis of 878 consecutive patients with PTC who underwent thyroidectomy from April 2016 to March 2017 was conducted. We explored the surrounding tissue of laryngeal entry point, during routine central lymph node dissection (CLND). The lymph node specimens were sent separately for routine histopathological examination. Thereafter, complications and follow-ups were recorded. LN-epRLNs were found in 73 of the 878 patients, with the metastatic rate of 3.76%. Univariate and multivariate analysis showed central lymph node metastases can serve as independent predictors for LN-epRLN metastasis. In summary, we confirmed the significance of LN-epRLN in metastasis and recurrence, which required precise anatomy and thorough CLND. In PTC patients, especially in suspicious presence of central cervical lymph node metastasis, attention should be given to excising the nodal tissue at the laryngeal entry point.

Quantitative Non-Gaussian Intravoxel Incoherent Motion Diffusion-Weighted Imaging Metrics and Surgical Pathology for Stratifying Tumor Aggressiveness in Papillary Thyroid Carcinomas

We assessed a priori aggressive features using quantitative diffusion-weighted imaging metrics to preclude an active surveillance management approach in patients with papillary thyroid cancer (PTC) with tumor size 1-2 cm. This prospective study enrolled 24 patients with PTC who underwent pretreatment multi-b-value diffusion-weighted imaging on a GE 3 T magnetic resonance imaging scanner. The apparent diffusion coefficient (ADC) metric was calculated from monoexponential model, and the perfusion fraction (f), diffusion coefficient (D), pseudo-diffusion coefficient (D*), and diffusion kurtosis coefficient (K) metrics were estimated using the non-Gaussian intravoxel incoherent motion model. Neck ultrasonography examination data were used to calculate tumor size. The receiver operating characteristic curve assessed the discriminative specificity, sensitivity, and accuracy between PTCs with and without features of tumor aggressiveness. Multivariate logistic regression analysis was performed on metrics using a leave-1-out cross-validation method. Tumor aggressiveness was defined by surgical histopathology. Tumors with aggressive features had significantly lower ADC and D values than tumors without tumor-aggressive features (P < .05). The absolute relative change was 46% in K metric value between the 2 tumor types. In total, 14 patients were in the critical size range (1-2 cm) measured by ultrasonography, and the ADC and D were significantly different and able to differentiate between the 2 tumor types (P < .05). ADC and D can distinguish tumors with aggressive histological features to preclude an active surveillance management approach in patients with PTC with tumors measuring 1-2 cm.

Intraoperative carbon nanoparticles mapping in secondary total thyroidectomy for recurrent thyroid nodules: Results of a 8-criterion case-match study (case control study)

BACKGROUND

The extent of total thyroidectomy in the management of multinodular goiter remains unclear. Compared to primary thyroidectomy, secondary total thyroidectomy is more difficult to perform and carries a significantly higher risk of postoperative complications such as recurrent laryngeal nerve (RLN) palsy or hypoparathyroidism. In this study, we aimed to evaluate the efficacy and safety of intraoperative carbon nanoparticle (CN) mapping in patients undergoing secondary total thyroidectomy.

METHODS

We performed a case-matched analysis of a prospectively maintained database using 8 specific criteria to compare perioperative outcomes after primary total thyroidectomy to those after secondary total thyroidectomy with intraoperative CN mapping. The criteria included age, sex, operative procedure, RLN/parathyroid glands (PGs) exploration, preoperative vocal cord calcium abnormalities, and pathological results. Thirty-five patients underwent secondary total thyroidectomy with intraoperative CN mapping due to recurrent thyroid nodules or development of nodules suspicious for malignancy after subtotal thyroidectomy. Fifty exact matches for all 8 criteria were identified from the database in our previous study, which included records of 3078 primary thyroidectomies without CNs. Perioperative outcomes, surgical technique, and complications were analyzed.

RESULTS

The RLNs were successfully identified in all 35 patients. Among three patients that experienced slight hoarseness, one had an RLN end-to-end anastomosis with subsequent improvement in the during the 12-month follow-up period. Two patients experienced changes in vocal tone, but recovered after several months. Two patients underwent parathyroid auto-transplantations, and subsequently presented with transient hypocalcaemia. Their symptoms gradually remitted within one year. Except for mean operation time, there were no statistically significant differences in complications between the primary total thyroidectomies and the secondary total thyroidectomy with CNs.

CONCLUSIONS

Intraoperative CN mapping, expert knowledge of the jugular anatomy, and standardized resection procedures can minimize the incidence of complications such as RLN palsy and hypoparathyroidism after secondary total thyroidectomy.

Diffusion-weighted magnetic resonance imaging for the detection of thyroid cancer

BACKGROUND

Nodular thyroid disease possesses the potential to harbor malignancy. Our aim was to evaluate the significance of cervical diffusion-weighted magnetic resonance imaging (DW-MRI) for the detection of malignant thyroid nodules.

METHODS

Sixty-five thyroid nodules from 58 patients who had undergone surgery were evaluated. Preoperative parameters, demographic data, ultrasound findings, fine-needle aspiration biopsy results and apparent diffusion coefficient (ADC) values of the nodules at DW-MRI were compared with the results from postoperative pathology examinations.

RESULTS

The "benign group" included 50 (76.9%) nodules, while 15 (23.1%) nodules constituted the "malignancy group". Minimum, maximum and mean ADC values of the nodules were significantly lower in the malignancy group (p < 0.05). The best cutoff value for the mean ADC value was 1.33 × 10-3 mm2/s, with a sensitivity of 66.67%, a specifity of 89.13%, a positive predictive value of 53.63% and a negative predictive value of 89.13%. A mean ADC value equal to or lower than 1.33 × 10-3 mm2/s was associated with 9 times higher risk of malignancy (odds ratio: 9.111, 95% confidence interval: 2.49-33.21).

CONCLUSIONS

The ADC value detected by cervical DW-MRI can be considered a predictive parameter for the detection of thyroid cancer.

Evaluation of Head and Neck Tumors with Functional MR Imaging

Head and neck cancer is one of the most common cancers worldwide. MR imaging-based diffusion and perfusion techniques enable the noninvasive assessment of tumor biology and physiology, which supplement information obtained from standard structural scans. Diffusion and perfusion MR imaging techniques provide novel biomarkers that can aid monitoring in pretreatment, during treatment, and posttreatment stages to improve patient selection for therapeutic strategies; provide evidence for change of therapy regime; and evaluate treatment response. This review discusses pertinent aspects of the role of diffusion and perfusion MR imaging and computational analysis methods in studying head and neck cancer.

Diagnostic accuracy of ultrasound-guided fine needle aspiration biopsy for thyroid malignancy: systematic review and meta-analysis

PURPOSE

To systematically appraise and summarize the available evidence about the diagnostic accuracy of ultrasound-guided fine needle aspiration biopsy (USFNA) for thyroid malignancy, and to explore the integration of these estimates with the probability of thyroid malignancy before USFNA.

METHODS

A comprehensive search of multiple databases from each database's inception to August 2014 was performed. Eligible studies included those that evaluated patients with thyroid nodules who underwent USFNA and subsequent evaluation by histopathology or long-term follow-up.

RESULTS

We identified 32 studies at moderate risk of bias evaluating the USFNA diagnostic characteristics for the diagnosis of thyroid malignancy. Results were imprecise and inconsistent across trials. The pooled likelihood ratio (LR) of thyroid malignancy for a benign USFNA result was 0.09 (95 % CI 0.06, 0.14; I (2) = 33 %), whereas the pooled LR for a malignant result was 197 (95 % CI, 68, 569; I (2) = 77 %). In the case of a suspicious for follicular neoplasm result, the pooled LR for malignancy was 0.6 (95 % CI, 0.4, 1.0; I (2) = 84 %) and 8.3 (95 % CI, 3.6, 19.2; I (2) = 89) for a result of suspicious for malignancy.

CONCLUSION

The available evidence regarding the diagnostic accuracy of USFNA warrants only limited confidence due to risk of bias, imprecision, and inconsistency. However, some USFNA results (benign, malignant) are likely very helpful, by significantly changing the pre-test probability of thyroid cancer.

Dynamic Contrast-Enhanced MR Imaging in Head and Neck Cancer: Techniques and Clinical Applications

In the past decade, dynamic contrast-enhanced MR imaging has had an increasing role in assessing the microvascular characteristics of various tumors, including head and neck cancer. Dynamic contrast-enhanced MR imaging allows noninvasive assessment of permeability and blood flow, both important features of tumor hypoxia, which is a marker for treatment resistance for head and neck cancer. Dynamic contrast-enhanced MR imaging has the potential to identify early locoregional recurrence, differentiate metastatic lymph nodes from normal nodes, and predict tumor response to treatment and treatment monitoring in patients with head and neck cancer. Quantitative analysis is in its early stage and standardization and refinement of technique are essential. In this article, we review the techniques of dynamic contrast-enhanced MR imaging data acquisition, analytic methods, current limitations, and clinical applications in head and neck cancer.

A reference agent model for DCE MRI can be used to quantify the relative vascular permeability of two MRI contrast agents

Dynamic Contrast Enhancement (DCE) MRI has been used to measure the kinetic transport constant, K(trans), which is used to assess tumor angiogenesis and the effects of anti-angiogenic therapies. Standard DCE MRI methods must measure the pharmacokinetics of a contrast agent in the blood stream, known as the Arterial Input Function (AIF), which is then used as a reference for the pharmacokinetics of the agent in tumor tissue. However, the AIF is difficult to measure in pre-clinical tumor models and in patients. Moreover the AIF is dependent on the Fahraeus effect that causes a highly variable hematocrit (Hct) in tumor microvasculature, leading to erroneous estimates of K(trans). To overcome these problems, we have developed the Reference Agent Model (RAM) for DCE MRI analyses, which determines the relative K(trans) of two contrast agents that are simultaneously co-injected and detected in the same tissue during a single DCE-MRI session. The RAM obviates the need to monitor the AIF because one contrast agent effectively serves as an internal reference in the tumor tissue for the other agent, and it also eliminates the systematic errors in the estimated K(trans) caused by assuming an erroneous Hct. Simulations demonstrated that the RAM can accurately and precisely estimate the relative K(trans) (R(Ktrans)) of two agents. To experimentally evaluate the utility of RAM for analyzing DCE MRI results, we optimized a previously reported multiecho (19)F MRI method to detect two perfluorinated contrast agents that were co-injected during a single in vivo study and selectively detected in the same tumor location. The results demonstrated that RAM determined R(Ktrans) with excellent accuracy and precision.

The role of proton MR spectroscopy and apparent diffusion coefficient values in the diagnosis of malignant thyroid nodules: preliminary results

PURPOSE

Performance of proton magnetic resonance spectroscopy (H-MRS) and apparent diffusion coefficient (ADC) values in the diagnosis of malignant thyroid nodules.

METHOD

In a retrospective study with malignant nodules of 14 patients, H-MRS and diffusion-weighted MR imaging (DWI) were performed. Choline (Cho) peak, Cho/creatine (Cr) ratio, and ADC values of malignant nodules were correlated with the five benign nodules and four normal-appearing thyroid lobe parenchymata. The gold standard reference was fine needle aspiration biopsy and histopathology.

RESULTS

At echo time 40-144-ms acquisitions, average Cho/Cr ratio for the malignant nodules was 2.95±1.54-5.30±2.38, cutoff values were >0.805 and >1.225, and ADC values were 0.06±0.02.

CONCLUSION

H-MRS acquisitions, DWI, and ADC mapping give diagnostic data about the nature of the nodules.