Posttreatment Head and Neck Cancer Imaging: Anatomic Considerations Based on Cancer Subsites.

Posttreatment imaging surveillance of head and neck cancer is challenging owing to complex anatomic subsites and diverse treatment modalities. Early detection of residual disease or recurrence through surveillance imaging is crucial for devising optimal treatment strategies. Posttreatment imaging surveillance is performed using CT, fluorine 18-fluorodeoxyglucose PET/CT, and MRI. Radiologists should be familiar with postoperative imaging findings that can vary depending on surgical procedures and reconstruction methods that are used, which is dictated by the primary subsite and extent of the tumor. Morphologic changes in normal structures or denervation of muscles within the musculocutaneous flap may mimic recurrent tumors. Recurrence is more likely to occur at the resection margin, margin of the reconstructed flap, and deep sites that are difficult to access surgically. Radiation therapy also has a varying dose distribution depending on the primary site, resulting in various posttreatment changes. Normal tissues are affected by radiation, with edema and inflammation occurring in the early stages and fibrosis in the late stages. Distinguishing scar tissue from residual tumor becomes necessary, as radiation therapy may leave behind residual scar tissue. Local recurrence should be carefully evaluated within areas where these postradiation changes occur. Head and Neck Imaging Reporting and Data System (NI-RADS) is a standardized reporting and risk classification system with guidance for subsequent management. Familiarity with NI-RADS has implications for establishing surveillance protocols, interpreting posttreatment images, and management decisions. Knowledge of posttreatment imaging characteristics of each subsite of head and neck cancers and the areas prone to recurrence empowers radiologists to detect recurrences at early stages. ©RSNA, 2024 Test Your Knowledge questions in the supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

2021 WHO Classification of Lung Cancer: Molecular Biology Research and Radiologic-Pathologic Correlation.

The 2021 World Health Organization (WHO) classification system for thoracic tumors (including lung cancer) contains several updates to the 2015 edition. Revisions for lung cancer include a new grading system for invasive nonmucinous adenocarcinoma that better reflects prognosis, reorganization of squamous cell carcinomas and neuroendocrine neoplasms, and description of some new entities. Moreover, remarkable advancements in our knowledge of genetic mutations and targeted therapies have led to a much greater emphasis on genetic testing than that in 2015. In 2015, guidelines recommended evaluation of only two driver mutations, ie, epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) fusions, in patients with nonsquamous non-small cell lung cancer. The 2021 guidelines recommend testing for numerous additional gene mutations for which targeted therapies are now available including ROS1, RET, NTRK1-3, KRAS, BRAF, and MET. The correlation of imaging features and genetic mutations is being studied. Testing for the immune biomarker programmed death ligand 1 is now recommended before starting first-line therapy in patients with metastatic non-small cell lung cancer. Because 70% of lung cancers are unresectable at patient presentation, diagnosis of lung cancer is usually based on small diagnostic samples (ie, biopsy specimens) rather than surgical resection specimens. The 2021 version emphasizes differences in the histopathologic interpretation of small diagnostic samples and resection specimens. Radiologists play a key role not only in evaluation of tumor and metastatic disease but also in identification of optimal biopsy targets. ©RSNA, 2024 Test Your Knowledge questions in the supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

Imaging of salivary gland cancers derived from a sublingual gland herniated into the submandibular space: a report of three cases.

Sublingual gland herniation into the submandibular space through a mylohyoid muscle defect is a common anatomical variation; however, salivary gland cancers that arise from a herniated sublingual gland have not been described yet. Here, we report three patients with salivary gland cancers originating from a herniated sublingual gland. All tumors were detected as palpable submandibular masses, located anterior to the submandibular gland, medial to the mandible, and lateral to the mylohyoid muscle, with contact with the sublingual gland through a mylohyoid muscle defect. Intraoperative findings confirmed that the masses were derived from herniated sublingual glands. Pathological examination showed one case of mucoepidermoid carcinoma and two cases of adenoid cystic carcinoma. Imaging findings of the tumor location, in addition to the continuity with the sublingual gland through the mylohyoid muscle defect, are crucial for accurately diagnosing the tumor origin, which is essential for determining the appropriate clinical management.

Imaging Approach for Cervical Lymph Node Metastases from Unknown Primary Tumor.

Neck swelling due to lymph node (LN) metastasis is one of the initial symptoms of head and neck cancer, and in some cases, the primary tumor is not clinically evident. The purpose of imaging for LN metastasis from an unknown primary site is to identify the primary tumor or detect its absence, which leads to the correct diagnosis and optimal treatment. The authors discuss diagnostic imaging approaches for identifying the primary tumor in cases of unknown primary cervical LN metastases. The distribution and characteristics of LN metastases may help locate the primary site. Unknown primary LN metastasis often occurs at nodal levels II and III, and in recent reports, these were mostly related to human papillomavirus (HPV)-positive squamous cell carcinoma of the oropharynx. Another characteristic imaging finding suggestive of metastasis from HPV-associated oropharyngeal cancer is a cystic change in LN metastases. Other characteristic imaging findings such as calcification may help predict the histologic type and locate the primary site. In cases of LN metastases at nodal levels IV and VB, a primary lesion located outside the head and neck region must also be considered. One clue for detecting the primary lesion at imaging is the disruption of anatomic structures, which can help in identifying small mucosal lesions or submucosal tumors at each subsite. Additionally, fluorine 18 fluorodeoxyglucose PET/CT may help identify a primary tumor. These imaging approaches for identifying primary tumors enable prompt identification of the primary site and assist clinicians in making the correct diagnosis. © RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Imaging of diffuse fibroepithelial polyps on surgical free flap in oral cancer patients: two case reports.

Fibroepithelial polyp (FEP) is a common benign tumor occurring in the skin and genitourinary tract, and there are no reports of multiple FEPs occurring on the myocutaneous flap. We report two cases of FEPs occurring diffusely on the skin tissue of the free anterolateral thigh flap after surgical reconstruction for oral squamous cell carcinoma. Clinically, multiple papillary nodules on the myocutaneous flap gradually increased. CT and MRI showed multiple papillary nodules on an enhanced layer covering the entire myocutaneous flap. PET/CT showed high uptake. One case was diagnosed with FEPs by surgery, the other by biopsy. The tumor-limited localization on the myocutaneous flap, characteristic morphology showing multiple papillary projection with an enhanced layer, and MRI signal showing patchy mild elevation of the apparent diffusion coefficient value may help in differential diagnosis from tumor recurrence or secondary carcinoma of the myocutaneous flap on diagnostic imaging.

Imaging of Malignant Minor Salivary Gland Tumors of the Head and Neck.

Minor salivary gland carcinomas (MSGCs) are nonminor tumors in the head and neck region and account for about half of all salivary gland carcinomas. Imaging evaluation based on the anatomy of minor salivary and mucous glands in the head and neck region as well as invasion patterns in each site helps in identifying optimal treatment modalities and planning suitable treatment strategies. MSGCs can be divided radiologically into localized and invasive subtypes on the basis of the clinical utility of such categorization. Characteristic invasion patterns of the invasive type include deep submucosal extension, bone marrow infiltration, and perineural spread, which are difficult to assess clinically. MSGCs easily invade adjacent structures because of their submucosal location and may spread along the muscles, nerves, periosteum, and dura mater. Moreover, the tumor may spread into the bone marrow without obvious bone destruction. In addition to imaging classification, examining the anatomy and distribution of the minor salivary glands, including the palatal, lingual, buccal, labial, and retromolar glands, as well as other mucous glands, including the glands of the sinonasal cavity and nasopharynx, lacrimal glands, ceruminous glands, laryngeal glands, and tracheal glands, facilitates MSGC diagnosis and tumor extension assessment. The authors review the precise anatomy of the minor salivary and mucous glands in the head and neck region, discuss the MSGC imaging classifications, and describe how to evaluate the extent of MSGCs in each site on the basis of the imaging classification and invasion patterns. ©RSNA, 2020.

Prognostic impact of home oxygen therapy on patients with resected non-small-cell lung cancer with interstitial lung disease.

PURPOSE: Non-small-cell lung cancer (NSCLC) patients with interstitial lung disease (ILD) have a poor prognosis. The present study evaluated the prognostic impact of home oxygen therapy (HOT) in NSCLC patients with ILD. METHODS: Overall, 3099 consecutive patients underwent complete resection of stage IA to IIIA NSCLC at our institution between 2002 and 2016. ILD was diagnosed and categorized based on high-resolution computed tomography. The criteria for HOT included less than 90% resting oxygen saturation in the peripheral arteries and severe exertional dyspnea. We retrospectively compared the overall survival between ILD patients with and without HOT. RESULTS: ILD was observed in 150 (5%) patients. Seventeen (11%) patients needed HOT at discharge. The incidences of usual interstitial pneumonia (UIP) pattern (p = 0.03) and blood loss (p < 0.01) were significantly higher in the patients requiring HOT than in those without HOT. Significantly more patients developed complications (p = 0.04) in the HOT group than in the non-HOT group, with three (18%) having acute exacerbations. The 3-year overall survival rate was significantly lower in the HOT patients than in those without HOT (28% vs. 63%, p = 0.03). CONCLUSIONS: Patients requiring postoperative HOT showed a significantly poorer prognosis after complete resection than those without HOT. Therefore, the indication for surgery should be investigated cautiously in order to prevent the need for postoperative HOT.

Frequency and predictors of detecting early locoregional recurrence/disease progression of oral squamous cell carcinoma with high-risk factors on imaging tests before postoperative adjuvant radiotherapy.

BACKGROUND: To clarify the frequency and predictors of detecting early locoregional recurrence/disease progression (LR/DP) during the interval between surgery and postoperative adjuvant radiotherapy with/without chemotherapy in patients with oral squamous cell carcinoma. METHODS: Data on 65 patients who had undergone the initial radical surgery for previously untreated oral squamous cell carcinoma which were scheduled to receive adjuvant radiotherapy with/without chemotherapy were reviewed. RESULTS: Of the 65 patients, 63 (97%) were margin-positive/close and/or extracapsular extension-positive (hereinafter, high-risk factors). Eighteen (28%) patients had abnormal findings suggestive of LR/DP on postoperative imaging. Fifteen (23%) patients were diagnosed with LR/DP and treatment policy was changed. Univariate and multivariate analyses revealed higher frequencies of abnormal findings suggestive of LR/DP (univariate/multivariate analysis, p = 0.020/0.036), diagnosing of LR/DP, and changing the treatment policy (univariate/multivariate analysis, p = 0.042/0.046), among the patients who underwent postoperative diagnostic imaging tests or radiotherapy-planning contrast-enhanced (CE) CT without diagnostic imaging tests as compared with those who underwent radiotherapy-planning non-CECT without such tests. CONCLUSION: The frequency of detecting of early LR/DP before postoperative adjuvant treatment in oral squamous cell carcinoma patients with high-risk factors was high. Furthermore, postoperative diagnostic imaging tests and radiotherapy-planning CECT may be useful to detect early LR/DP in oral squamous cell carcinoma patients before postoperative adjuvant therapy.

Endoleak detection after endovascular aneurysm repair using unenhanced MRI with flow suppression technique: Feasibility study in comparison with contrast-enhanced CT.

OBJECTIVES: To evaluate the feasibility of unenhanced motion-sensitized-driven equilibrium (MSDE)-prepared balanced turbo field echo (BTFE) sequences for detecting endoleaks after endovascular aneurysm repair (EVAR). METHODS: Forty-six patients treated with EVAR for aortic and/or iliac arterial aneurysms underwent contrast-enhanced CT and MSDE-prepared BTFE sequences with and without flow suppression. Two independent observers reviewed these sequences and their subtraction images and assigned confidence levels for detecting endoleaks. Relative contrast values were calculated by dividing signal intensities by those of paraspinal muscles. CT provided the reference standard. RESULTS: CT showed types I and II endoleaks in one and ten patients, respectively. Areas under receiver operating characteristic curves were 0.92 and 0.97 for observers 1 and 2, respectively. Sensitivity, specificity, accuracy, positive predictive value and negative predictive value of both observers were 91 (10/11), 91(32/35), 91 (42/46), 77 (10/13) and 97 % (32/33), respectively. Relative contrast values of endoleaks and flowing blood significantly decreased by flow suppression on MSDE-prepared BTFE images (P = 0.002 and P < 0.0001 respectively), and were significantly higher than those of the excluded aneurysms on subtraction images (P = 0.003 and P = 0.001, respectively). CONCLUSIONS: Unenhanced MSDE-prepared BTFE sequences are feasible for detecting endoleaks. KEY POINTS: • Flow suppression significantly reduces endoleak signals on MSDE-prepared BTFE images. • Subtraction images of MSDE-prepared BTFE sequences ± flow suppression demonstrate endoleaks. • MSDE-prepared BTFE sequences indicate high diagnostic values (>90 %) except PPV (77 %). • MSDE-prepared BTFE sequences need further refinement to reduce false positives. • Endoleaks can be detected without contrast injection using MSDE-prepared BTFE sequences.

Radiologic feature of complications after artificial urinary sphincter implantation following total prostatectomy.

Incontinence following total prostatectomy for prostate cancer significantly impairs patient's quality of life. In severe cases, implantation of an artificial urinary sphincter (AUS) has shown favorable outcomes, enhancing continence by constricting the bulbous urethra. The AUS system consists of a pressure-maintaining balloon, control pump serving as the operational switch, cuff that constricts the urethra, and tubes and connectors that link these components, maintaining a continuous circuit through an internal pressure medium. Most instances of AUS dysfunction are attributed to circuit leaks leading to a reduction in internal pressure, which is identifiable on imaging by fluid accumulation around the circuit, balloon collapse, control pump deformation, and air within the circuit. When the AUS circuit is uncompromised, dysfunction may arise from issues such as the inability to compress the pump due to pain or displacement outside the scrotum or urinary tract obstruction caused by bladder hemorrhage/hematoma. Imaging plays a pivotal role in the evaluation of urinary tract injuries, hematomas/seromas, and infections associated with AUS placement or replacement. Understanding the function of AUS and its appearance on CT imaging is essential for accurately assessing AUS dysfunction and post-implantation complications, guiding clinical decision-making and improving patient care outcomes.

A new simpler image quality index based on body size for FDG-PET/CT.

Noise equivalent count density (NEC density ) is often used to evaluate the image quality of whole-body fluorodeoxyglucose tomography tests. However, this index is calculated using the patient volume, which is difficult to obtain at every facility. In this study, we proposed new image quality indices that can be evaluated at all facilities. In total, 94 patients were enrolled in the study. The correlations of patients' body weight and BMI with volume were examined. New image quality indices normalized by body weight and BMI were defined as NEC bw and NEC bmi , respectively. Correlations between NEC bw , NEC bmi , and NEC density were examined. Further, the correlations between these two new indices and visual scores were evaluated. Good correlations were observed between volume and body weight (r = 0.861, P  < 0.001) and between volume and BMI (r = 0.728, P  < 0.001). NEC bw and NEC bmi correlated well with NEC density (r = 0.954 for NEC bw and r = 0.897 for NEC bmi , P  < 0.001). These correlations improved when the examined bed positions were set to the same number. Additionally, the correlations of visual scores with NEC bw and NEC bmi were similar to those between the visual score and NEC density . Our investigation indicated that the newly proposed image quality metrics, NEC bw and NEC bmi , were easily calculated and as useful as NEC density for evaluating image quality when subjects had similar physiques.

Synaptonemal complex protein SYCP3 impairs mitotic recombination by interfering with BRCA2.

The meiosis-specific synaptonemal complex protein SYCP3 has been reported to be aberrantly expressed in tumours. However, in contrast to its well-defined function in meiosis, its possible role in mitotic cells is entirely unknown. Here, we show that SYCP3 is expressed in a range of primary tumours and that it impairs chromosomal integrity in mitotic cells. Expression of SYCP3 inhibits the homologous recombination (HR) pathway mediated by RAD51, inducing hypersensitivity to DNA-damaging agents such as a poly(ADP-ribose) polymerase (PARP) inhibitor and chromosomal instability. SYCP3 forms a complex with BRCA2 and inhibits its role in HR. These findings highlight a new mechanism for chromosomal instability in cancer and extend the range of PARP-inhibitor sensitive tumours to those expressing SYCP3.

Computed tomography-based radiomic analysis for predicting pathological response and prognosis after neoadjuvant chemotherapy in patients with locally advanced esophageal cancer.

PURPOSE: Accurate prediction of prognosis and pathological response to neoadjuvant chemotherapy (NAC) is crucial for optimizing treatment strategies for patients with locally advanced esophageal cancer (LA-EC). This study aimed to investigate the use of radiomics for pretreatment CT in predicting the pathological response of patients with LA-EC to NAC. METHODS: Overall, 144 patients (145 lesions) with LA-EC who underwent pretreatment contrast-enhanced CT and then received NAC followed by surgery with pathological tumor regression grade (TRG) analysis were enrolled. The obtained dataset was randomly divided into training and validation cohorts using fivefold cross-validation. CT-based radiomic features were extracted followed by the feature selection process using the variance threshold, SelectKBest, and least absolute shrinkage and selection operator methods. The radiomic model was constructed using six machine learning classifiers, and predictive performance was evaluated using ROC curve analysis in the training and validation cohorts. RESULTS: All patients were divided into responders (n = 40, 28%) and non-responders (n = 104, 72%) based on the TRG results and a statistically significant split by overall survival analysis (0.899 [0.754-0.961] vs. 0.630 [0.510-0.729], respectively). There were no significant differences between responders and non-responders in terms of age, sex, tumor size, tumor location, or histopathology. The mean AUC of fivefold in the validation cohort was 0.720 (confidence interval [CI]: 0.594-0.982), and the best AUC of the radiomic model using logistic regression to predict the non-responders was 0.815 (CI: 0.626-1.000, sensitivity 0.620, specificity 0.860). CONCLUSION: A radiomic model derived from contrast-enhanced CT may help stratify chemotherapy effect prediction and improve clinical decision-making.

Characteristic imaging findings in a patient with chronic expanding hematoma on the floor of the mouth.

Chronic expanding hematoma (CEH) is defined as chronic hematoma enlargement for more than 1 month. Although CEH rarely occurs on the floor of the mouth, the need to distinguish these cases from malignant disease is critical, given the need for potentially extensive resection in patients with malignancy. We report a case of CEH on the floor of the mouth, which required differentiation from malignant tumor. A 42-year-old woman was referred to our hospital for a submucosal mass on the right floor of the mouth, with a diagnosis of class 3 on aspiration cytology. Computed tomography revealed a submucosal mass with peripheral calcification on the floor of the mouth, which exhibited a hypointense rim on T2-weighted imaging and gradual nodular-like enhancement in the periphery on contrast-enhanced magnetic resonance imaging. Enucleation was performed to reach a definitive diagnosis, and CEH was confirmed pathologically. Well-defined morphology, presence of calcification, a hypointense rim on T2-weighted imaging, and weak peripheral nodular-like enhancement may be characteristic findings of CEH on the floor of the mouth. Accordingly, these imaging features may aid in differentiating CEH from low-grade malignancies and in determining the optimal management strategy.

Computed tomography findings of hepatobiliary systems in patients with immune checkpoint inhibitor-induced liver injury.

PURPOSE: The incidence of immune checkpoint inhibitor (ICI)-induced liver injury has increased recently; however, its imaging characteristics remain unclear. This study aimed to characterize the computed tomography (CT) findings of ICI-induced liver injury. METHODS: This was a single-center retrospective study of patients with ICI-induced liver injury who underwent CT between January 2020 and December 2021. Two board-certified radiologists independently evaluated the CT findings of the patients before the start of ICI therapy (pre-CT) and at the onset of ICI-induced liver injury (post-CT) to determine the presence or absence of imaging findings suggestive of hepatitis and cholangitis. ICI-induced liver injury was classified into three categories based on the CT findings: hepatitis alone, cholangitis alone, and overlapped (cholangitis plus hepatitis). RESULTS: A total of 19 patients were included in this study. Bile duct dilatation, bile duct wall thickening, non-edematous gallbladder wall thickening, hepatomegaly, periportal edema, and gallbladder wall edema were observed in the post-CT images of 12 (63.2%), 9 (60%), 11 (57.9%), 8 (42.1%), 6 (31.6%), and 2 (10.5%) patients, respectively. Wall thickening in the perihilar, distal, intrapancreatic bile duct and the cystic duct were observed in 53.3%, 60%, 46.7%, and 26.7% of the study population, respectively. Regarding the classification of ICI-induced liver injury, cholangitis alone was most common (36.8%), followed by overlapped (26.3%) and hepatitis alone (26.3%). CONCLUSIONS: Patients with ICI-induced liver injury demonstrated a higher incidence of biliary abnormalities than hepatic abnormalities on CT images; nonetheless, future studies with larger sample sizes are needed to validate these findings.

A case of Epstein-Barr virus-positive mucocutaneous ulcer of the hypopharynx: a mimicker of hypopharyngeal squamous cell carcinoma.

Epstein-Barr virus-positive mucocutaneous ulcer (EBVMCU) is a new disease, described by the World Health Organization in 2017. It has been recognized as a specific type of immunodeficiency-associated lymphoproliferative disorder. Since patients with EBVMCU present with only cutaneous or mucosal ulcers, it is difficult to clinically distinguish them from carcinoma. A 72-year-old man, who took methotrexate (MTX) (12 mg/week) for rheumatoid arthritis, was referred to our hospital because endoscopy revealed an ulcerated mass in the left pyriform sinus, suggesting hypopharyngeal squamous cell carcinoma. Contrast-enhanced computed tomography and magnetic resonance imaging revealed an ill-defined mass in the left pyriform sinus without lymphadenopathy in the head and neck region. A biopsy of the ulcerative lesion in the hypopharynx was performed, and lymphoproliferative disease was suspected, based on the histopathological findings. Two weeks after MTX withdrawal, the lesions in the hypopharynx disappeared. The patient was diagnosed with EBVMCU, based on the clinical and histopathological findings. This is the first case report of EBVMCU of the hypopharynx. EBVMCU should be considered as a differential diagnosis in immunocompromised patients with hypopharyngeal mucosal ulcers without lymph node or organ involvement.

Subtraction iodine imaging with area detector CT to improve tumor delineation and measurability of tumor size and depth of invasion in tongue squamous cell carcinoma.

PURPOSE: Tumor size and depth of invasion (DOI) are mandatory assessments for tumor classification in tongue cancer but are often non-assessable on CT due to dental artifacts. This study investigated whether subtraction iodine imaging (SII) would improve tumor delineation and measurability. MATERIALS AND METHODS: Fifty-seven consecutive patients with tongue cancer, who underwent scanning with a 320-row area detector CT with contrast administration and were treated with surgical resection, were retrospectively evaluated. CT was reconstructed with single-energy projection-based metallic artifact reduction (sCT). SII was generated by subtracting the pre-contrast volume scans from the post-contrast volume scans using a high-resolution deformable registration algorithm. MRI scans were also evaluated for comparing the ability of measurements. Two radiologists visually graded the tumor delineation using a 5-point scale. Tumor size and DOI were measured wherever possible. The tumor delineation score was compared using the Wilcoxon signed-rank method. Spearman's correlations between imaging and pathological measurements were calculated. Intraclass correlation coefficients of measurements between readers were estimated. RESULTS: The tumor delineation score was greater on sCT-plus-SII than on sCT alone (medians: 3 and 1, respectively; p < 0.001), with higher number of detectable cases observed with sCT-plus-SII (36/57 [63.2%]) than sCT alone (21/57 [36.8%]). Tumor size and DOI measurability were higher with sCT-plus-SII (29/57 [50.9%]) than with sCT alone (17/57 [29.8%]). MRI had the highest detectability (52/57 [91.2%]) and measurability (46/57 [80.7%]). Correlation coefficients between radiological and pathological tumor size and DOI were similar for sCT (0.83-0.88), sCT-plus-SII (0.78-0.84), and MRI (0.78-0.90). Intraclass correlation coefficients were higher than 0.95 for each modality. CONCLUSIONS: SII improves detectability and measurability of tumor size and DOI in patients with oral tongue squamous cell carcinoma, thus increasing the diagnostic potential. SII may also be beneficial for cases unevaluable on MRI due to artifacts or for patients with contraindications to MRI.

Predisposing conditions for bacterial meningitis in children: what radiologists need to know.

A variety of underlying diseases can predispose infants and children to bacterial meningitis (BM). For the diagnosis, treatment, and prevention of its recurrence, radiologists should be familiar with its predisposing conditions so that they can suggest the appropriate imaging approach. Predisposing conditions of BM can be broadly classified into two categories: infection spread from the adjacent tissue to the cerebrospinal fluid (CSF) space and immunodeficiency. Diseases in the former category are further divided according to regardless of whether there is a structural defect between the CSF space and the adjacent tissue. When a structural defect is suspected in a patient with BM, computed tomography (CT) of the head and magnetic resonance (MR) imaging are first-line imaging examinations. Radionuclide cisternography should be implemented as a second-line step to identify the CSF leak site. In patients with suspected parameningeal infection without any structural defect, such as sinusitis or otitis media/mastoiditis, CT or MR images can identify not only the disease itself but also the associated intracranial complications. The purpose of this article is to discuss the diagnostic approach and imaging findings associated with the variety of conditions predisposing patients to recurrent BM, focusing on the role of radiology in their management.

Radiation pneumonitis after palliative radiotherapy in cancer patients with interstitial lung disease.

PURPOSE: The risk of radiation pneumonitis (RP) after palliative radiotherapy (RT) in cancer patients with interstitial lung disease (ILD) remains unclear. This study aimed to investigate the incidence, severity, and predictive factors of RP among patients with ILD who received palliative RT. METHODS AND MATERIALS: The medical records of cancer patients with ILD who received palliative RT involving a lung field between January 2008 and December 2019 were retrospectively reviewed. Screening for ILD was performed by using the ICD-10 diagnosis code, and the ILD was evaluated on the basis of pretreatment computed tomography (CT). RP was scored using Common Terminology Criteria for Adverse Events, version 5.0. Associations between both clinical and dosimetric factors and RP were assessed by univariate and multivariate analyses. RESULTS: Sixty-two patients were included in the analysis. The median prescribed physical dose of RT was 25 Gy (range, 6-40 Gy). The RP was graded 1, 2, 3, 4, and 5 in 6 (10%), 3 (5%), 1 (2%), 2 (3%), and 6 (10%) patients, respectively. The median time to onset of grade 3 or more RP (≥Gr3 RP) was 39 days (range, 10-155). The results of the multivariate analysis indicated that ILD pattern was a significant predictive factor for ≥Gr3 RP (odds ratio, 12.0; 95% confidence interval, 1.02-1664; P < 0.05). CONCLUSIONS: RT involving a lung field, even when prescribed with palliative intent, should be administered carefully to ILD patients. Evaluation of the ILD pattern on pretreatment CT images may be of help in determining whether to perform RT.

Extra-nodal extension in head and neck cancer: how radiologists can help staging and treatment planning.

Extranodal extension (ENE) is a significant prognostic factor in p16-negative head and neck squamous-cell carcinoma and is classified as N3b by the American Joint Committee on Cancer 8th edition. While most previous radiological studies have focused on the diagnostic performance of pathological ENE, radiologists should be able to provide more clinically relevant information on this entity. The purpose of this article is to review the clinical implications of ENE, to describe key imaging features of ENE with clinical and histopathological correlations and to discuss evaluation of ENE for clinical staging, treatment planning, and predicting the response to treatment. First, we discuss the basics of ENE, including definitions of pathological and clinical ENE and its association with imaging findings. Second, we describe the ENE extension pattern at each location according to level system. The crucial structures determining the choice of treatment include the deep fascia in the deep cervical layer, internal and common carotid arteries, and mediastinal structures. Invasion of the muscles, internal jugular vein, nerves, or mandible also affect the surgical procedure. Finally, we discuss assessment of nodal metastasis after chemoradiotherapy.