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Purpose: This study aimed to assess the imaging features and postoperative natural course of 18F-fluorodeoxyglucose (FDG) uptake in the cervical muscles after neck dissection. Materials and methods: This study included 83 patients who underwent preoperative and postoperative 18F-FDG-PET/CT and were diagnosed with head and neck malignancy after neck dissection. Postoperative 18F-FDG-PET/CT was performed within 5 years after neck dissection. Preoperative and postoperative FDG uptake of the trapezius, sternocleidomastoid, scalene, pectoralis major, and deltoid muscles was visually assessed. Increased postoperative uptake was visually defined as higher postoperative FDG uptake than the preoperative one in the corresponding muscle. The maximum standardized uptake value (SUVmax) was measured in cases with increased postoperative uptakes. Results: Increased postoperative uptakes were observed in 43 patients (52%). The trapezius (31/83, 37%), sternocleidomastoid (19/83, 23%), and scalene (12/83, 14%) muscles were involved, as opposed to the pectoralis major and deltoid muscles were not. Increased postoperative uptakes were observed on the dissected side in all 43 patients. Significant differences between SUVmax estimated from the mixed-effects model and postoperative months were observed in the trapezius muscle (Coefficient (β) = −0.038; 95% confidence interval (CI): [−0.047, −0.028]; p < 0.001) and sternocleidomastoid muscle (β = −0.015; 95% CI: [−0.029, −0.001]; p = 0.046). Conclusions: Increased postoperative uptakes in the cervical muscles were observed on the dissected side in approximately half of the patients after neck dissection. The SUVmax in the trapezius and sternocleidomastoid muscles decreased after surgery over time. [ABSTRACT FROM AUTHOR]

Simple Summary: The diagnostic performance and interobserver variability of the contrast-enhanced CT currently used for evaluating arterial involvement from pancreatic cancer has limitations. The purpose of this study was to investigate the utility of reconstructed CT images perpendicular to the artery for assessing arterial involvement from pancreatic cancer and to compare the interobserver variability between it and the current diagnostic imaging method. We found that reconstructed CT images perpendicular to the splenic artery were feasible and showed less interobserver variability than current diagnostic method images. The purpose of this study was to investigate the utility of reconstructed CT images perpendicular to the artery for assessing arterial involvement from pancreatic cancer and compare the interobserver variability between it and the current diagnostic imaging method. This retrospective study included patients with pancreatic cancer in the pancreatic body or tail who underwent preoperative pancreatic protocol CT and distal pancreatectomy. Five radiologists used axial and coronal CT images (current method) and perpendicular reconstructed CT images (proposed method) to determine if the degree of solid soft-tissue contact with the splenic artery was ≤180° or >180°. The generalized estimating equations were used to compare the diagnostic performance of solid soft-tissue contact >180° between the current and proposed methods. Fleiss' ĸ statistics were used to assess interobserver variability. The sensitivity and negative predictive value for diagnosing solid soft-tissue contact >180° were higher (p < 0.001 for each) and the specificity (p = 0.003) and positive predictive value (p = 0.003) were lower in the proposed method than the current method. Interobserver variability was improved in the proposed method compared with the current method (ĸ = 0.87 vs. 0.67). Reconstructed CT images perpendicular to the artery showed higher sensitivity and negative predictive value for diagnosing solid soft-tissue contact >180° than the current method and demonstrated improved interobserver variability. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to determine the MRI features of sporadic/simple lymphoepithelial cyst (SLEC) of the parotid gland. Methods: Ten patients (seven men, three women; mean age, 60 years; age range, 38–77 years) with histopathologically and clinically proven SLEC of the parotid gland who underwent MRI before surgical resection were enrolled in this study. No enrolled patient had HIV infection or Sjögren syndrome. MRI findings of SLEC were retrospectively assessed. Results: We confirmed 10 SLECs larger than 10 mm with a mean maximum diameter of 26.6 mm (range, 12–42 mm). Nine patients (90%) had a single cyst, and one (10%) had a large cyst accompanied by small cysts (<10 mm) within the ipsilateral parotid gland. Eight SLECs (80%) were unilocular, and two (20%) were bilocular, with complete septa. Among seven SLECs (70%) with internal septa, five unilocular SLECs (50%) had incomplete septa. Six SLECs (60%) had eccentric cyst wall thickening, and five (50%) were surrounded by small solid nodules that were isointense relative to lymph node. On T1-weighted images, all cyst contents were homogeneously hyperintense relative to cerebrospinal fluid. Conclusion: SLECs of the parotid gland are usually single unilocular lesions. Internal septa, eccentric cyst wall thickening, and small solid nodules surrounding the lesion were often observed. Cyst contents are always homogeneously hyperintense on T1-weighted images. [ABSTRACT FROM AUTHOR]

Simple Summary: Non-alcoholic steatohepatitis (NASH) may progress into liver cirrhosis and hepatocellular carcinoma (HCC). NASH has been recognized as a major cause of HCC, which is the third leading cause of cancer-related deaths worldwide. However, the development of drug therapy for NASH and ensuing liver cirrhosis and HCC has been limited due to the lack of reliable preclinical models of the NASH progression. Here, we developed a new diet-induced mouse model of NASH-liver cirrhosis-HCC sequence. Compared with the previous mouse model, this model demonstrated shorter occurrence of NASH, liver cirrhosis, and HCC and more similar pathological characteristics to humans. Considering the similarity to clinicopathological features of human NASH in addition to very high reproducibility, generality, and convenience, our mouse model is expected to be used for the development of novel compounds for the treatment of NASH patients. Non-alcoholic steatohepatitis (NASH), which is the most severe manifestation of non-alcoholic fatty liver disease (NAFLD), has been recognized as a major hepatocellular carcinoma (HCC) catalyst. However, the molecular mechanism of NASH-liver fibrosis-HCC sequence remains unclear and a specific and effective treatment for NASH has not yet been established. The progress in this field depends on the availability of reliable preclinical models which show the steady progression to NASH, liver cirrhosis, and HCC. However, most of the NASH mouse models that have been described to date develop NASH generally for more than 24 weeks and there is an uncertainty of HCC development. To overcome such shortcomings of experimental NASH studies, we established a novel NASH-HCC mouse model with very high reproducibility, generality, and convenience. We treated male C57BL/6J mice with a newly developed choline-deficient and methionine-restricted high-fat diet, named OYC-NASH2 diet, for 60 weeks. Treatment of OYC-NASH2 diet for 3 weeks revealed marked steatosis, lobular inflammation, and fibrosis, histologically diagnosed as NASH. Liver cirrhosis was observed in all mice with 48-week treatment. Liver nodules emerged at 12 weeks of the treatment, > 2 mm diameter liver tumors developed in all mice at 24 weeks of the treatment and HCC appeared after 36-week treatment. In conclusion, our rapidly progressive and highly reproducible NASH-liver cirrhosis-HCC model is helpful for preclinical development and research on the pathogenesis of human NAFLD-NASH-HCC. Our mouse model would be useful for the development of novel chemicals for NASH-HCC-targeted therapies. [ABSTRACT FROM AUTHOR]

Background The characteristics of magnetic resonance imaging (MRI) findings among osteofibrous dysplasia (OFD), fibrous dysplasia (FD), and nonossifying fibroma (NOF) have yet to be determined. Aims This study determines the differences of MRI features among OFD, FD, and NOF of the long bone. Patients and Methods This study included 39 patients including 10 OFD, 13 with FD, and 16 with NOF of the long bone. All patients underwent preoperative MRI and histological examination. We retrospectively reviewed the MRIs and compared the imaging findings among the three pathologies. Results The maximum diameter was significantly different among OFD (47.0 ± 18.6 mm), FD (59.0 ± 35.0 mm), and NOF (33.3 ± 15.0 mm) (p < 0.05). Multiplicity (60%, p < 0.01), eccentric distribution (100%, p < 0.05), septation (70%, p < 0.01), homogeneous intensity on T2-weighted images (70%, p < 0.01), homogeneous contrast enhancement (63%, p < 0.05), and intense contrast enhancement (88%, p < 0.01) were significantly more frequent in OFD. Centric distribution (69%, p < 0.01), cyst formation (54%, p < 0.01), and fluid-fluid level formation (31%, p < 0.01) were significantly more frequent in FD. Eccentric distribution (100%, p < 0.01), heterogeneous on T2-weighted images (100%, p < 0.01), predominant hypointensity on T2-weighted images (44%, p < 0.01), and the presence of intralesional hypointensity on T2-weighted images (88%, p < 0.01) were significantly more frequent in NOF. Conclusion MRI features could differentiate OFD, FD, and NOF of the long bone. [ABSTRACT FROM AUTHOR]

Recently, diffusion-weighted imaging (DWI) is an essential magnetic resonance imaging (MRI) protocol for head and neck imaging in clinical practice as it plays an important role in lesion detection, tumor extension evaluation, differential diagnosis, therapeutic effect prediction, therapy evaluation, and recurrence diagnosis. Especially in the parotid gland, several studies have already attempted to achieve accurate differentiation between benign and malignant tumors using DWI. A conventional single-shot echo-planar-based DWI is widely used for head and neck imaging, whereas advanced DWI sequences, such as intravoxel incoherent motion, diffusion kurtosis imaging, periodically rotated overlapping parallel lines with enhanced reconstruction, and readout-segmented echo-planar imaging (readout segmentation of long variable echo-trains), have been used to characterize parotid tumors. The mean apparent diffusion coefficient values are easily measured and useful for assessing cellularity and histological characteristics, whereas advanced image analyses, such as histogram analysis, texture analysis, and machine and deep learning, have been rapidly developed. Furthermore, a combination of DWI and other MRI protocols has reportedly improved the diagnostic accuracy of parotid tumors. This review article summarizes the current state of DWI in differentiating parotid tumors. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the prognostic value of 18F-fludeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) and MRI features in patients with high-risk and very-high-risk cutaneous squamous cell carcinoma (cSCC). This study included 54 consecutive patients with surgically resected primary high-risk and very-high-risk cSCC who underwent pre-operative FDG-PET/CT and/or MRI. Among them, 14 patients (26%) had recurrences. We retrospectively reviewed the FDG-PET/CT (n = 34) and MRI (n = 48) and investigated the clinical significance and prognostic value of imaging features in cSCC. On FDG-PET/CT, the maximum standardized uptake value (SUVmax) of the primary tumor (13.0 ± 6.4 vs. 6.9 ± 5.3, p < 0.05) was higher in cSCC with recurrence than in cSCC without recurrence. On MRI, the maximum diameter of the lesion (46.8 ± 24.1 mm vs 30.4 ± 17.0 mm, p < 0.05) and the frequency of muscle/tendon/bone invasion (42% vs 11%, p < 0.05) were significantly greater in cSCC with recurrence than in cSCC without recurrence. In the univariate analysis, prognostic factors for recurrence were SUVmax of the primary tumor (p < 0.01), the maximum diameter of the lesion (p < 0.05), and depth of invasion (p < 0.05). The areas under the receiver operating characteristic curves of the SUVmax (0.78) were superior to those of the maximum diameter (0.71) and depth of invasion (0.60). SUVmax, maximum diameter, and depth of invasion were useful parameters for prognostic factors predicting recurrence in patients with high-risk and very-high-risk cSCC. SUVmax represents a prognostic factor. [ABSTRACT FROM AUTHOR]

The present case study reports contrast-enhanced magnetic resonance findings in three patients with histopathologically proven IgG4-related chronic sclerosing sialadenitis of the submandibular gland. All three patients presented with painless swelling of the submandibular region. The contrast-enhanced T1-weighted images showed reticular enhancement of the swollen submandibular gland. Radiological–pathological correlation revealed that the characteristic reticular enhancement corresponded to fibrosis and to inflammatory cell infiltration in the interlobular septa and in the periductal region of the submandibular gland. [ABSTRACT FROM AUTHOR]

Sometimes, radiologists encounter malignant skin tumors (MSTs) during image interpretation. As MSTs require different clinical management modalities for each histological subtype, accurate preoperative diagnosis is essential. The histological subtypes of MST can be easily assessed by visual inspection or biopsy. Therefore, the significant role of radiological imaging in MSTs is to evaluate the extent of local invasion, nodal involvement, and distant metastasis, and the histological estimation of MSTs by radiological imaging has not been reported until a few years ago. However, recent studies have revealed characteristic radiological features for differential diagnosis of MSTs, such as configuration, intratumoral homogeneity, signal intensity, cyst formation, and hemorrhage. Other important clinical data for determining the histological subtype of MST include age, gender, and site of occurrence. MSTs can be categorized as epidermal, melanocytic, adnexal, and mesenchymal tumors based on the origin and have distinctive characteristics. Hence, this review article was designed to describe the clinical and radiological features of MSTs. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to evaluate computed tomography and magnetic resonance imaging of benign trichilemmal cysts and proliferating trichilemmal tumours. Methods: Nineteen histologically confirmed cutaneous lesions with trichilemmal keratinisation (12 trichilemmal cysts and seven proliferating trichilemmal tumours) were enrolled. Among them, 10 lesions (six trichilemmal cysts and four proliferating trichilemmal tumours) were examined by computed tomography, while 13 lesions (eight trichilemmal cysts and five proliferating trichilemmal tumours) were examined by magnetic resonance imaging. Computed tomography and magnetic resonance imaging characteristics were retrospectively reviewed. RESULTS: Sixteen lesions (84%, 10 trichilemmal cysts and six proliferating trichilemmal tumours) occurred on the scalp. Lobulated margins were observed in five lesions (26%, three trichilemmal cysts and two proliferating trichilemmal tumours). With respect to computed tomography attenuation, calcification (>200 Hounsfield units) was observed in seven lesions (70%, five trichilemmal cysts and two proliferating trichilemmal tumours), hyperdense areas (≥80 and ≤200 Hounsfield units) in six (60%, three trichilemmal cysts and three proliferating trichilemmal tumours), and soft tissue density areas (<80 Hounsfield units) in nine (90%, five trichilemmal cysts and four proliferating trichilemmal tumours). On T1-weighted images, intratumoral hyperintensity was only observed in eight trichilemmal cysts but no proliferating trichilemmal tumours (100% vs. 0%, P <0.01). On T2-weighted images, hypointense rim and intratumoral hypointensity was observed in all 13 lesions (100%, eight trichilemmal cysts and five proliferating trichilemmal tumours), and linear or reticular hypointensity was observed in 10 (77%, six trichilemmal cysts and four proliferating trichilemmal tumours). Conclusion: Trichilemmal cysts and proliferating trichilemmal tumours predominantly occurred on the scalp with calcification, and usually exhibited linear or reticular T2 hypointensity. Intratumoral T1 hyperintensity may be a useful imaging feature for differentiating trichilemmal cysts from proliferating trichilemmal tumours. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to evaluate imaging findings of cutaneous angiosarcoma (cAS) of the scalp compared with those of cutaneous squamous cell carcinoma (cSCC). Methods: This study included 15 patients with primary cAS and 10 with primary cSCC of the scalp. Seven patients with cAS and eight with cSCC underwent magnetic resonance imaging, and 11 patients with cAS and eight with cSCC underwent 18F-fluorodeoxyglucose–positron emission tomography/computed tomography imaging. Imaging findings for both pathologies were retrospectively reviewed and compared. Results: All 15 cAS cases were elevated lesions with an obtuse angle, invading the subcutaneous fat tissue. Multiple lesions were observed in only five cAS cases (33%) and no cSCC cases. Maximum diameter-to-height ratio was significantly higher in cAS than in cSCC (3.3 ± 1.0 versus 2.3 ± 0.6; p < 0.01). On T2-weighted images, intratumoral hypointensity (86% versus 13%; p < 0.01) and mixed hyper- and hypointensity (71% versus 0%; p < 0.01) were observed more frequently in cAS than in cSCC. No significant differences were observed between cAS and cSCC regarding flow void (29% versus 25%; p = 0.656). Maximum standardized uptake values were marginally significantly lower in cAS than in cSCC (5.6 ± 3.1 versus 10.5 ± 6.6; p = 0.078). Conclusions: Cases of cAS of the scalp always exhibited flat elevated lesions with invasion of the subcutaneous fat tissue. Compared with cSCC, intratumoral hypointensity and mixed hyper- and hypointensity on T2-weighted images were more frequent in cAS. These findings will help with the differential diagnosis of cAS. [ABSTRACT FROM AUTHOR]

Background: There has been no study that has reported magnetic resonance imaging (MRI) findings of extrauterine high-grade serous carcinomas (HGSCs) that have been histologically determined by the new criteria.Purpose: To assess MRI findings of extrauterine HGSCs based on new pathologic criteria.Material and Methods: Fifty patients with histopathologically proven extrauterine HGSCs, who underwent pretreatment gadolinium-enhanced MRI, were included in this study. After surgery, the primary sites were histopathologically determined based on new criteria for primary site assignment in extrauterine HGSCs as follows: fallopian tube (n = 34); ovary (n = 9); primary peritoneal HGSC (n = 1); and tubo-ovarian (n = 6). We retrospectively reviewed MR images and compared the MR findings between tubal and ovarian primaries.Results: MRI patterns with tubal primaries were classified as ovarian cancer (62%), peritoneal cancer (35%), and fallopian tube cancer (3%). MRI patterns with ovarian primaries were classified as ovarian cancer (78%) and peritoneal cancer (22%). The frequency of the involvement of the fallopian tube, ovary, peritoneum, uterus, and lymph node was not significantly different between the two pathologies. There was no significant difference in the abnormal amount of ascites, hemorrhagic ascites, or characteristics of the ovarian lesions between the two pathologies.Conclusion: On MR images, tubal primaries almost always exhibited ovarian or peritoneal cancer pattern, but rarely exhibited fallopian tube cancer pattern. MR findings could not accurately differentiate between tubal and ovarian primaries; therefore, histopathologic investigation is essential for determination of the primary site of extrauterine HGSCs. [ABSTRACT FROM AUTHOR]

Purpose: On T2-weighted images, most solid lesions exhibit nonspecific intermediate signal intensity, whereas most cystic lesions exhibit marked hyperintensity. In contrast, on T2-weighted images, a relatively small number of lesions exhibit hypointensity. This review aimed to differentiate, according to the histopathologic findings, head and neck lesions showing hypointensity on T2-weighted images. Methods: In this review article, hypointense head and neck lesions on T2-weighted images are classified into the following nine categories: calcified or osseous lesions, granulomatous lesions, fibrous lesions, mucous- or proteincontaining lesions, hemosiderin-containing lesions, melanin-containing lesions, thyroglobulin-containing lesions, rapid blood flow, and air-filled spaces. Conclusion: Knowledge regarding hypointense head and neck lesions on T2-weighted images allows radiologists to make accurate differential diagnoses. Key points • Hypointense head and neck lesions on T2-weighted images include calcified or osseous lesions, granulomatous lesions, fibrous lesions, mucous- or protein-containing lesions, hemosiderin-containing lesions, melanin-containing lesions, thyroglobulin-containing lesions, rapid blood flow, and air-filled spaces. • Radiologists should recognize the hypointense head and neck lesions on T2-weighted images for the final correct diagnosis, resulting in appropriate patient management. [ABSTRACT FROM AUTHOR]

Scalp lesions can be classified as congenital, traumatic, inflammatory, or neoplastic in origin. Although patients presenting with scalp masses are frequently seen in daily practice, differentiation of scalp lesions is often challenging for radiologists who are not familiar with the imaging of cutaneous lesions. The majority of scalp lesions are fortunately benign, with cystic lesions accounting for over 50% of all benign scalp lesions. Such lesions include trichilemmal cysts (pilar cysts), sebaceoma, epidermoid cysts, dermoid cysts, and teratoid cysts. Radiologists may also occasionally encounter benign neoplasms of the scalp, including melanocytic nevi, keratoacanthoma, pilomatricoma, neurofibroma, and lipoma. Malignant scalp tumors are uncommon; however, they carry a potential risk of delayed detection, resulting in poorer outcomes. Most scalp lesions show nonspecific imaging findings, although some possess characteristic features on CT and MRI. Radiologists must be familiar with the appearances of common scalp lesions to reach an accurate diagnosis. Hence, the aim of this article is to describe the clinical and imaging features of scalp lesions. [ABSTRACT FROM AUTHOR]

A variety of neoplastic and non-neoplastic lesions of the parotid gland can present with a predominantly cystic architecture, and although radiologists frequently encounter cystic parotid tumors, other non-neoplastic lesions should also be included in the differential diagnoses of cystic parotid lesions. Non-neoplastic cystic lesions are usually classified as either congenital/acquired cystic lesions or inflammatory/infectious lesions. Adequate knowledge about these rare conditions is essential for appropriate diagnosis and optimal treatment strategy. This review article describes CT and MR imaging features of non-neoplastic cystic lesions of the parotid gland and provides helpful suggestions on the differential diagnoses for cystic parotid lesions. [ABSTRACT FROM AUTHOR]

Pleomorphic adenoma (PA) is the most common salivary gland tumor and is characterized by cytomorphological and architectural diversity. On CT and MR images, PAs are shown as well-defined lesions occasionally accompanied by characteristic lobulated contours. On T2-weighted images, typical PAs show marked hyperintensity, which reflects the abundant myxochondroid stroma, with a hypointense rim indicating the fibrous capsule. However, intratumoral signal intensity varies according to the cellular density, proportion of epithelial and stromal components, and type of stromal components. In addition, a variety of secondary histological changes, including fibrosis, lipometaplasia, ossification, cystic degeneration, and infarction, occur rarely in PAs; therefore, they are associated with difficulty in differential diagnosis from other salivary gland tumors. This review article describes the common and uncommon CT and MR imaging features of PA of the salivary glands. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to evaluate the efficacy of using MRI findings to differentiate superficial spindle cell lipomas (SCLs) from atypical lipomatous tumor/well‐differentiated liposarcomas (ALT/WDLs). Methods: This study included 12 patients with histopathologically proven superficial SCLs and 11 with ALT/WDLs. MRI findings for both pathologies were retrospectively reviewed and compared between the two pathologies. Results: The neck, upper back, and shoulder regions were more frequent locations of SCLs than of ALT/WDLs (100% vs 55%, p < 0.05), whereas no significant differences were observed in age and sex. The median maximum diameter of the lesion was smaller in SCLs than in ALT/WDLs (44 mm [interquartile range (IQR): 35–63] vs 102 mm [IQR: 86–119], p < 0.05). On T1 weighted images, non‐fatty area was more frequently observed in SCLs than in ALT/WDLs (73% vs 25%, p < 0.05), and the median rate of non‐fatty area was larger in SCLs than in ALT/WDLs (7.5% [IQR: 1.0–53] vs 0% [IQR: 0–0.2], p < 0.05). On fat‐suppressed T2 weighted images, a solid hyperintense area was more frequently observed in SCLs than in ALT/WDLs (83% vs 27%, p < 0.05). Conclusion: The maximum diameter, non‐fatty area on T1 weighted images, and solid hyperintense area on fat‐suppressed T2 weighted images were useful imaging features for differentiating superficial SCLs from ALT/WDLs. Advances in knowledge: In superficial lipomatous tumors, small tumor size and non‐fatty solid area were valuable findings for diagnosing SCLs. [ABSTRACT FROM AUTHOR]