Sun-Won Park

Ultrasonography Diagnosis and Imaging-Based Management of Thyroid Nodules: Revised Korean Society of Thyroid Radiology Consensus Statement and Recommendations

The rate of detection of thyroid nodules and carcinomas has increased with the widespread use of ultrasonography (US), which is the mainstay for the detection and risk stratification of thyroid nodules as well as for providing guidance for their biopsy and nonsurgical treatment. The Korean Society of Thyroid Radiology (KSThR) published their first recommendations for the US-based diagnosis and management of thyroid nodules in 2011. These recommendations have been used as the standard guidelines for the past several years in Korea. Lately, the application of US has been further emphasized for the personalized management of patients with thyroid nodules. The Task Force on Thyroid Nodules of the KSThR has revised the recommendations for the ultrasound diagnosis and imaging-based management of thyroid nodules. The review and recommendations in this report have been based on a comprehensive analysis of the current literature and the consensus of experts.

Can Necrotizing Infectious Fasciitis Be Differentiated from Nonnecrotizing Infectious Fasciitis with MR Imaging

PURPOSE To retrospectively evaluate whether magnetic resonance (MR) imaging findings can be used to differentiate necrotizing infectious fasciitis (NIF) from nonnecrotizing infectious fasciitis (non-NIF). MATERIALS AND METHODS Institutional review board approval was obtained, but patient consent was not required for this retrospective review of records and images because patient anonymity was preserved. Thirty patients (seven with NIF, 23 with non-NIF) were included in the study. The following imaging findings were analyzed on fat-suppressed T2-weighted MR images: (a) signal intensity in the deep fascia (low, high, or mixed high and low), (b) thickness of abnormal signal intensity in the deep fascia (≥3 mm or <3 mm), (c) pattern of abnormal signal intensity in muscle (no abnormality, peripheral bandlike signal intensity, or patchy high signal intensity), (d) degree of deep fascia involvement (partial or extensive), and (e) degree of compartment involvement (fewer than three compartments or three or more compartments). On contrast material-enhanced fat-suppressed T1-weighted images, the contrast enhancement patterns of the abnormal deep fascia (no enhancement, enhancement, or enhancement with nonenhancing portion) and the muscle (no abnormality, peripheral bandlike signal intensity, or patchy high signal intensity) were evaluated. The presence of abscesses in the subcutaneous fat layer was evaluated with all sequences. RESULTS The patients with NIF had a significantly greater frequency of (a) thick (≥3 mm) abnormal signal intensity on fat-suppressed T2-weighted images, (b) low signal intensity in the deep fascia on fat-suppressed T2-weighted images, (c) a focal or diffuse nonenhancing portion in the area of abnormal signal intensity in the deep fascia, (d) extensive involvement of the deep fascia, and (e) involvement of three or more compartments in one extremity (P < .05). CONCLUSION MR imaging is potentially helpful for differentiating NIF from non-NIF. SUPPLEMENTAL MATERIAL http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101164/-/DC1.

Nonoverlapping Y-configuration stenting technique with dual closed-cell stents in wide-neck basilar tip aneurysms.

BACKGROUND: Stent-assisted coiling is increasingly used to treat wide-neck intracranial aneurysms to protect the lumen of the parent artery from coil protrusion. This technique is insufficient for treating some aneurysms, depending on their configurations. OBJECTIVE: To describe a variant of the Y-configuration stent-assisted coiling technique for the treatment of basilar tip aneurysms with wide necks. METHODS: This technique, called the nonoverlapping Y stenting technique, consists of the deployment of a closed-cell self-expandable stent from the basilar trunk to a posterior cerebral artery and then placement of a second stent from the basilar bifurcation to the other posterior cerebral artery without overlapping the first stent. The proximal flared portion of the second stent was located at the neck of the aneurysm. Coil embolization was performed under dual-stent protection. RESULTS: We successfully filled wide-neck aneurysms with coils under stent protection by forming a bridge across the aneurysmal neck without overlapping 2 closed-cell stents. Six basilar tip aneurysms were successfully treated with this technique. CONCLUSION: The nonoverlapping Y stenting technique is a good alternative to traditional stent-assisted coiling. This technique is particularly suitable for the treatment of broad-neck bifurcation aneurysms. ABBREVIATION: PCA, posterior cerebral artery

Emphasis on the MR imaging findings of brown tumor: a report of five cases

ObjectiveBrown tumors are focal reactive osteolytic lesions that are encountered in patients with primary or secondary hyperparathyroidism, and these tumors have nonspecific magnetic resonance (MR) imaging findings. However, there are only a few reports on MR imaging of brown tumors. The purpose of this study is to describe the spectrum of MR imaging findings of brown tumors.Materials and methodsThe MR imaging features of five patients with clinical and pathological evidence of brown tumor were retrospectively reviewed by two radiologists. The patients had primary hyperparathyroidism, which was confirmed as parathyroid adenoma (n = 2) and parathyroid carcinoma (n = 3). The MR images were evaluated for the presence of solid or cystic portions, the signal intensity of the lesions, the contrast enhancement pattern and the presence of cortex destruction and fluid-fluid levels.ResultsTwelve bone lesions were detected on the MR images of five patients; three lesions in two patients, four lesions in one patient, and one lesion in two patients. The tumor was solid in three lesions, mixed solid and cystic in four, and cystic in five. All the solid lesions were accompanied by mixed lesions. Discontinuity of the cortex and adjacent soft-tissue enhancement were seen in all the solid lesions. Fluid-fluid levels were seen in two cases within the cystic component of the mixed lesions and cystic lesions.ConclusionsThe five patients with brown tumor demonstrated a wide spectrum of MR imaging findings. There are few lesions that are osteolytic on the radiographs and that show a short T2 on MR imaging, such as brown tumor. Multiple cystic or mixed lesions are the expected findings of brown tumors.

Ultrasonographic findings of medullary thyroid cancer: differences according to tumor size and correlation with fine needle aspiration results

Background Complete initial tumor resection is a key prognostic factor in patients with medullary thyroid carcinomas (MTCs), hence precise preoperative diagnosis is very important. Thyroid ultrasonography (US) is a first-line modality and can lead to the appropriate next diagnostic procedure. Purpose To evaluate the US characteristics of MTCs, to evaluate whether or not there is a difference in US findings according to tumor size, and to correlate the US findings with fine needle aspiration (FNA) results. Material and Methods Thirty patients with 36 MTCs who had a preoperative US and a MTC diagnosis based on surgery were included. The US findings of each nodule were retrospectively analyzed in terms of size, internal content, shape, margin, echogenicity of solid portions, the presence of calcifications, the type of calcifications, and the presence of a halo by two radiologists. Each lesion was classified as suspiciously malignant, indeterminate, or probably benign according to known US criteria. The FNA results for the 28 MTCs were reviewed from the cytology reports. Results The lesion size varied from 5.7–90.0 mm (mean 22.4 ± 14.4 mm). The predominate US findings included solid internal content (91.7%), round-to-oval shape (63.9%), smooth margins (52.8%), hypoechogenicity (72.2%), and micro- or macro-calcifications (61.1%). Twenty-six nodules (72.2%) were classified as suspiciously malignant, and 10 nodules (27.8%) were classified as indeterminate. Of the 27 MTCs classified as suspiciously malignant, 21 MTCs (77.8%) had micro- or macro-calcifications, which was the most common malignant feature. MicroMTCs (≤1 cm) had spiculated margins more frequently than macroMTCs (66.7% vs. 13.3%; P = 0.014) and macroMTCs (>1 cm) had smooth margins more frequently than microMTCs (63.4% vs. 0%; P = 0.006). Twenty-one MTCs with positive FNA results showed smooth margins and a larger size more frequently than seven MTCs with negative FNA results (66.7% vs. 14.3%; P = 0.029; mean diameter, 24.28 ± 13.45 mm vs. 11.74 ± 4.73 mm, P = 0.004, respectively). Conclusion Based on US, the majority of MTCs can be classified as suspiciously malignant due to the presence of micro- or macro-calcifications. Small MTC size (≤ 10 mm) and a smooth margin may be factors predicting false-negative FNA results.

Head and neck squamous cell carcinoma: Differentiation of histologic grade with standard- and high-b-value diffusion-weighted MRI

The correlation between the histologic grades and the apparent diffusion coefficient (ADC) in head and neck squamous cell carcinomas (HNSCCs) remains unclear. This study aimed to evaluate the potential of diffusion‐weighted MRI (DW‐MRI) at both standard and high b values to differentiate the histologic grades of HNSCC.

Usefulness of Single Voxel Proton MR Spectroscopy in the Evaluation of Hippocampal Sclerosis

Objective The purpose of our study was to determine the ability of H-1 MR spectroscopy (MRS) to lateralize the lesion in patients with hippocampal sclerosis. Materials and Methods Twenty healthy volunteers and 25 patients with intractable temporal lobe epilepsy whose MR imaging diagnosis was unilateral hippocampal sclerosis were included. This diagnosis was based on the presence of unilateral atrophy and/or high T2 signal intensity of the hippocampus. Single-voxel H-1 MRS was carried out on a 1.5-T unit using PRESS sequence (TE, 136 msec). Spectra were obtained from hippocampal areas bilaterally with volumes of interest (VOIs) of 6.0 cm3 and 2.25 cm3 in healthy volunteers, and of either 6.0 cm3 (n = 14) or 2.25 cm3 (n = 11) in patients. Metabolite ratios of NAA/Cho and NAA/Cr were calculated from relative peak height measurements. The capability of MRS to lateralize the lesion and to detect bilateral abnormalities was compared with MR imaging diagnosis as a standard of reference. Results In healthy volunteers, NAA/Cho and NAA/Cr ratios were greater than 0.8 and 1.0, respectively. In patients, the mean values of these ratios were significantly lower on the lesion side than on the contralateral side, and lower than those of healthy volunteers (p < .05). The overall correct lateralization rate of MRS was 72% (18/25); this rate was lower with a VOI of 6.0 cm3 than of 2.25 cm3 (64% versus 82%, p < .05). Bilateral abnormalities on MRS were found in 24% (6/25) of cases. Conclusion Although its rate of correct lateralization is low, single-voxel H-1 MRS is a useful and promising diagnostic tool in the evaluation of hippocampal sclerosis, particularly for the detection of bilateral abnormalities. To improve the diagnostic accuracy of H-1 MRS, further investigation, including the use of a smaller VOI and measurement of the absolute amount of metabolites, are needed.

Ocular adnexal IgG4-related disease: CT and MRI findings

Background/aims To evaluate CT and MRI findings of histopathologically proven ocular adnexa IgG4-related disease. Methods Study subjects included 18 patients with histopathologically proven ocular adnexal IgG4-related disease. CT (n=16) and MR (n=3) images were retrospectively evaluated for location, laterality, shape, margin, attenuation on precontrast CT images, T1 and T2 signal intensity on precontrast MRI , internal architecture, ocular adnexal lesion enhancement patterns, sialadenitis of major salivary glands, cervical lymph node enlargement and perilesional bony change. Results Lacrimal gland enlargement was observed in 16 cases. Extraglandular lesions were observed in the medial canthus (n=2) and extraconal space (n=2). Bilateral supraorbital and infraorbital nerves, pterygopalatine fossa and cavernous sinus involvement were observed in one case. All ocular adnexal lesions showed well defined margins, isoattenuation on precontrast CT images, isointensity on T1- and hypointensity on T2-weighted images, homogenous internal arcithecture and enhancement patterns and bone remodelling without destruction. Conclusions Ocular adnexal IgG4-related disease can involve the lacrimal gland, medial canthus, extraconal space, supraorbital and infraorbital nerves, pterygopalatine fossa and cavernous sinus. A diagnosis of ocular adnexal IgG4-related disease should be considered in lesions with the typical imaging features described herein.

Differentiation of Glioblastoma from Brain Metastasis: Qualitative and Quantitative Analysis Using Arterial Spin Labeling MR Imaging

Purpose To evaluate the diagnostic performance of cerebral blood flow (CBF) by using arterial spin labeling (ASL) perfusion magnetic resonance (MR) imaging to differentiate glioblastoma (GBM) from brain metastasis. Materials and Methods The institutional review board of our hospital approved this retrospective study. The study population consisted of 128 consecutive patients who underwent surgical resection and were diagnosed as either GBM (n = 89) or brain metastasis (n = 39). All participants underwent preoperative MR imaging including ASL. For qualitative analysis, the tumors were visually graded into five categories based on ASL-CBF maps by two blinded reviewers. For quantitative analysis, the reviewers drew regions of interest (ROIs) on ASL-CBF maps upon the most hyperperfused portion within the tumor and upon peritumoral T2 hyperintensity area. Signal intensities of intratumoral and peritumoral ROIs for each subject were normalized by dividing the values by those of contralateral normal gray matter (nCBFintratumoral and nCBFperitumoral, respectively). Visual grading scales and quantitative parameters between GBM and brain metastasis were compared. In addition, the area under the receiver-operating characteristic curve was used to evaluate the diagnostic performance of ASL-driven CBF to differentiate GBM from brain metastasis. Results For qualitative analysis, GBM group showed significantly higher grade compared to metastasis group (p = 0.001). For quantitative analysis, both nCBFintratumoral and nCBFperitumoral in GBM were significantly higher than those in metastasis (both p < 0.001). The areas under the curve were 0.677, 0.714, and 0.835 for visual grading, nCBFintratumoral, and nCBFperitumoral, respectively (all p < 0.001). Conclusion ASL perfusion MR imaging can aid in the differentiation of GBM from brain metastasis.

Computed tomography and magnetic resonance imaging findings of nasal cavity hemangiomas according to histological type.

Objective To compare computed tomography (CT) and magnetic resonance imaging (MRI) findings between two histological types of nasal hemangiomas (cavernous hemangioma and capillary or lobular capillary hemangioma). Materials and Methods CT (n = 20; six pre-contrast; 20 post-enhancement) and MRI (n = 7) images from 23 patients (16 men and seven women; mean age, 43 years; range, 13-73 years) with a pathologically diagnosed nasal cavity hemangioma (17 capillary and lobular capillary hemangiomas and six cavernous hemangiomas) were reviewed, focusing on lesion location, size, origin, contour, enhancement pattern, attenuation or signal intensity (SI), and bony changes. Results The 17 capillary and lobular hemangiomas averaged 13 mm (range, 4-37 mm) in size, and most (n = 13) were round. Fourteen capillary hemangiomas had marked or moderate early phase enhancement on CT, which dissipated during the delayed phase. Four capillary hemangiomas on MRI showed marked enhancement. Bony changes were usually not seen on CT or MRI (seen on five cases, 29.4%). Half of the lesions (2/4) had low SI on T1-weighted MRI images and heterogeneously high SI with signal voids on T2-weighted images. The six cavernous hemangiomas were larger than the capillary type (mean, 20.5 mm; range, 10-39 mm) and most had lobulating contours (n = 4), with characteristic enhancement patterns (three centripetal and three multifocal nodular), bony remodeling (n = 4, 66.7%), and mild to moderate heterogeneous enhancement during the early and delayed phases. Conclusion CT and MRI findings are different between the two histological types of nasal hemangiomas, particularly in the enhancement pattern and size, which can assist in preoperative diagnosis and planning of surgical tumor excision.