Teaching Radiology to Medical Students in Canada; a Virtual, Integrative, Clinical Approach.

PURPOSE: To construct, apply, and evaluate a multidisciplinary approach in teaching radiology to Canadian medical students. METHODS: A multidisciplinary team of radiology and other disciplines experts designed an online 5-session course that was delivered to medical students. The topics of each session were clinical cases involving different systems. The target audience was medical students of Canadian schools. Pretests and post-tests were administered before and after each session respectively. An evaluation survey was distributed at the end of the course to gauge students' perceptions of this experience. RESULTS: An average of 425 medical students attended the live sessions. For each session, 405 students completed both the pre-tests and post-tests. In general, students scored an average of 56% higher on the post-test than on the pre-test. The final course survey was completed by 469 students. The survey results show that more than 98% of students found the course to meet or exceed their expectations. Over 80% of students agreed that the course increased their interest in radiology and about 81% agree that the topics presented were excellent and clinically important. The ratings in the final survey results also indicate that students increased their confidence in basic radiology skills after completing the course. CONCLUSIONS: The implementation of an integrative clinical approach to teaching radiology in a virtual setting is achievable. It provides efficient use of educational resources while being accessible by a large number of students across different medical schools.

Diagnostic Approach to Intrinsic Abnormality of Spinal Cord Signal Intensity.

Intramedullary cord hyperintensity at T2-weighted MRI is a common imaging feature of disease in the spinal cord, but it is nonspecific. Radiologists play a valuable role in helping narrow the differential diagnosis by integrating patient history and laboratory test results with key imaging characteristics. The authors present an algorithmic approach to evaluating intrinsic abnormality of spinal cord signal intensity (SI), which incorporates clinical evaluation results, time of onset (acute vs nonacute), cord expansion, and pattern of T2 SI abnormality. This diagnostic approach provides a practical framework to aid both trainees and practicing radiologists in workup of myelopathy.©RSNA, 2019.

Techniques and Approaches for Safe, High-Yield CT-Guided Suprahyoid Head and Neck Biopsies.

OBJECTIVE: The purpose of this article is to present imaging approaches and key technical, safety, and patient care best practices critical for safe, successful image-guided biopsy of head and neck masses. CONCLUSION: Image-guided sampling is an important adjunct to the diagnosis and management of head and neck masses and may be particularly useful when lesions are not accessible via an endoscope or by palpation-guided sampling. Appropriate workup is mandatory before the patient is scheduled for such a procedure. Once the procedure has been initiated, needle selection and technique are critical for increasing the diagnostic yield. Knowledge of the various head and neck biopsy approaches and their associated complications is important for optimal tissue sampling and minimization of morbidity.

The current role of diagnostic imaging in the preoperative workup for refractory neonatal brachial plexus palsy.

INTRODUCTION: Despite recent improvements in perinatal care, the incidence of neonatal brachial plexus palsy (NBPP) remains relatively common. CT myelography is currently considered to be the optimal imaging modality for evaluating nerve root integrity. Recent improvements in MRI techniques have made it an attractive alternative to evaluate nerve root avulsions (preganglionic injuries). AIM: We demonstrate the utility of MRI for the evaluation of normal and avulsed spinal nerve roots. We also show the utility of ultrasound in providing useful preoperative evaluation of the postganglionic brachial plexus in patients with NBPP.

Unusual Cause of Horner Syndrome 13 Years After In Situ Ductal Carcinoma.

Horner syndrome can be caused by a wide range of pathologies along the sympathetic nerve chain, from the hypothalamus to the orbit. Imaging workup of Horner syndrome is necessary given the potential for deadly lesions, especially in a patient with a previous cancer history. The authors report a case of a woman who presented with a preganglionic Horner syndrome secondary to vertebral metastasis from previously diagnosed breast cancer that involved the neural foramina at T1 and T2.

Inborn errors of metabolism: combining clinical and radiologic clues to solve the mystery.

OBJECTIVE: Inborn errors of metabolism in children can be challenging to interpret because of the similarity of their appearances on imaging. There are important clues to the diagnosis based on clinical history, head circumference (e.g., macrocephaly), geographic distribution of lesions (e.g., subcortical vs deep white matter or frontal vs parietooccipital), and other imaging features (e.g., contrast enhancement, calcification, cysts, and cortical dysplasia). CONCLUSION: In this article, we present an algorithm-based approach to diagnosing pediatric metabolic disease with a discussion of key imaging features.

Lateral geniculate lesions causing reversible blindness in a pre-eclamptic patient with a variant of posterior reversible encephalopathy syndrome.

Bilateral lateral geniculate nucleus (LGN) injury is a rare cause of vision loss. We describe a patient with pre-eclampsia who developed profound but reversible bilateral vision loss, bilateral serous retinal detachments, and magnetic resonance imaging signs of a variant of posterior reversible encephalopathy syndrome (PRES) that affected both LGNs and spared the retrogeniculate pathways. We provide evidence that the visual loss was not from the chorioretinal lesions but from the LGN lesions. The concurrence of PRES and lesions attributed to choroidal hypoperfusion provides support for the notion that vasoconstriction also underlies the pathogenesis of PRES.

Adaptive statistical iterative reconstruction: reducing dose while preserving image quality in the pediatric head CT examination.

BACKGROUND: Over the last decade there has been escalating concern regarding the increasing radiation exposure stemming from CT exams, particularly in children. Adaptive statistical iterative reconstruction (ASIR) is a relatively new and promising tool to reduce radiation dose while preserving image quality. While encouraging results have been found in adult head and chest and body imaging, validation of this technique in pediatric population is limited. OBJECTIVE: The objective of our study was to retrospectively compare the image quality and radiation dose of pediatric head CT examinations obtained with ASIR compared to pediatric head CT examinations without ASIR in a large patient population. MATERIALS AND METHODS: Retrospective analysis was performed on 82 pediatric head CT examinations. This group included 33 pediatric head CT examinations obtained with ASIR and 49 pediatric head CT examinations without ASIR. Computed tomography dose index (CTDIvol) was recorded on all examinations. Quantitative analysis consisted of standardized measurement of attenuation and the standard deviation at the bilateral centrum semiovale and cerebellar white matter to evaluate objective noise. Qualitative analysis consisted of independent assessment by two radiologists in a blinded manner of gray-white differentiation, sharpness and overall diagnostic quality. RESULTS: The average CTDIvol value of the ASIR group was 21.8 mGy (SD = 4.0) while the average CTDIvol for the non-ASIR group was 29.7 mGy (SD = 13.8), reflecting a statistically significant reduction in CTDIvol in the ASIR group (P < 0.01). There were statistically significant reductions in CTDI for the 3- to 12-year-old ASIR group as compared to the 3- to 12-year-old non-ASIR group (21.5 mGy vs. 30.0 mGy; P = 0.004) as well as statistically significant reductions in CTDI for the >12-year-old ASIR group as compared to the >12-year-old non-ASIR group (29.7 mGy vs. 49.9 mGy; P = 0.0002). Quantitative analysis revealed no significant difference in the homogeneity of variance in the ASIR group compared to the non-ASIR group. Radiologist assessment of gray-white differentiation, sharpness and overall diagnostic quality in ASIR examinations was not substantially different compared to non-ASIR examinations. CONCLUSION: The use of ASIR in pediatric head CT examinations allows for a 28% CTDIvol reduction in the 3- to 12-year-old age group and a 48% reduction in the >12-year-old age group without substantially affecting image quality.

MRI to delineate the gross tumor volume of nasopharyngeal cancers: which sequences and planes should be used?

BACKGROUND: Magnetic resonance imaging (MRI) has been found to be better than computed tomography for defining the extent of primary gross tumor volume (GTV) in advanced nasopharyngeal cancer. It is routinely applied for target delineation in planning radiotherapy. However, the specific MRI sequences/planes that should be used are unknown. METHODS: Twelve patients with nasopharyngeal cancer underwent primary GTV evaluation with gadolinium-enhanced axial T1 weighted image (T1) and T2 weighted image (T2), coronal T1, and sagittal T1 sequences. Each sequence was registered with the planning computed tomography scans. Planning target volumes (PTVs) were derived by uniform expansions of the GTVs. The volumes encompassed by the various sequences/planes, and the volumes common to all sequences/planes, were compared quantitatively and anatomically to the volume delineated by the commonly used axial T1-based dataset. RESULTS: Addition of the axial T2 sequence increased the axial T1-based GTV by 12% on average (p = 0.004), and composite evaluations that included the coronal T1 and sagittal T1 planes increased the axial T1-based GTVs by 30% on average (p = 0.003). The axial T1-based PTVs were increased by 20% by the additional sequences (p = 0.04). Each sequence/plane added unique volume extensions. The GTVs common to all the T1 planes accounted for 38% of the total volumes of all the T1 planes. Anatomically, addition of the coronal and sagittal-based GTVs extended the axial T1-based GTV caudally and cranially, notably to the base of the skull. CONCLUSIONS: Adding MRI planes and sequences to the traditional axial T1 sequence yields significant quantitative and anatomically important extensions of the GTVs and PTVs. For accurate target delineation in nasopharyngeal cancer, we recommend that GTVs be outlined in all MRI sequences/planes and registered with the planning computed tomography scans.

Extended nnU-Net for Brain Metastasis Detection and Segmentation in Contrast-Enhanced Magnetic Resonance Imaging With a Large Multi-Institutional Data Set.

PURPOSE: The purpose of this study was to investigate an extended self-adapting nnU-Net framework for detecting and segmenting brain metastases (BM) on magnetic resonance imaging (MRI). METHODS AND MATERIALS: Six different nnU-Net systems with adaptive data sampling, adaptive Dice loss, or different patch/batch sizes were trained and tested for detecting and segmenting intraparenchymal BM with a size ≥2 mm on 3 Dimensional (3D) post-Gd T1-weighted MRI volumes using 2092 patients from 7 institutions (1712, 195, and 185 patients for training, validation, and testing, respectively). Gross tumor volumes of BM delineated by physicians for stereotactic radiosurgery were collected retrospectively and curated at each institute. Additional centralized data curation was carried out to create gross tumor volumes of uncontoured BM by 2 radiologists to improve the accuracy of ground truth. The training data set was augmented with synthetic BMs of 1025 MRI volumes using a 3D generative pipeline. BM detection was evaluated by lesion-level sensitivity and false-positive (FP) rate. BM segmentation was assessed by lesion-level Dice similarity coefficient, 95-percentile Hausdorff distance, and average Hausdorff distance (HD). The performances were assessed across different BM sizes. Additional testing was performed using a second data set of 206 patients. RESULTS: Of the 6 nnU-Net systems, the nnU-Net with adaptive Dice loss achieved the best detection and segmentation performance on the first testing data set. At an FP rate of 0.65 ± 1.17, overall sensitivity was 0.904 for all sizes of BM, 0.966 for BM ≥0.1 cm3, and 0.824 for BM <0.1 cm3. Mean values of Dice similarity coefficient, 95-percentile Hausdorff distance, and average HD of all detected BMs were 0.758, 1.45, and 0.23 mm, respectively. Performances on the second testing data set achieved a sensitivity of 0.907 at an FP rate of 0.57 ± 0.85 for all BM sizes, and an average HD of 0.33 mm for all detected BM. CONCLUSIONS: Our proposed extension of the self-configuring nnU-Net framework substantially improved small BM detection sensitivity while maintaining a controlled FP rate. Clinical utility of the extended nnU-Net model for assisting early BM detection and stereotactic radiosurgery planning will be investigated.

Utility of dual-energy CT virtual keV monochromatic series for the assessment of spinal transpedicular hardware-bone interface.

OBJECTIVE: Our aim was to evaluate the utility of dual-energy CT (DECT) virtual kilo-electron volt (keV) monochromatic images for the visualization of the transpedicular screw-bone interface after spinal fusion. MATERIALS AND METHODS: This retrospective study included postfusion spine CT studies performed from October 2011 through April 2012 on a dual-energy 64-MDCT unit (Discovery CT750 HD). Studies were postprocessed on an Advantage Windows workstation (version 4.4) by two neuroradiologists with creation of monochromatic images from 40 to 140 keV. Each reader graded the screw-bone interfaces on the 70-keV images (used for clinical interpretation) and on the monochromatic series using a 5-point scale (1 [uninterpretable] to 5 [excellent]). The grades of the interfaces were compared using the Wilcoxon signed rank test to detect differences between the 70-keV image and the monochromatic series. RESULTS: Ninety-two transpedicular screws in 10 patients were studied. Significant improvement in the visibility of the hardware-bone interface was seen on the monochromatic series compared with the 70-keV images: The median grade for the monochromatic series was 4 (range, 2-5) for both readers, whereas the median grade for the 70-keV images was 3 (range, 2-4) for reader 1 and 2 (range, 2-3) for reader 2 (both, p < 0.001). The interobserver agreement using weighted kappa was 0.51 for grading screw-bone interface visualization. The volume CT dose index was 29.5 mGy in all patients and the mean dose-length product was 805.2 mGy × cm. CONCLUSION: Monochromatic images generated on gemstone spectral DECT are beneficial in the reduction of metallic streak artifact and enable better visualization of the hardware-bone interface than the 70-keV series in patients treated with spinal transpedicular screw fixation.

Differentiation of benign and malignant neck pathologies: preliminary experience using spectral computed tomography.

PURPOSE: The objective of this study was to evaluate spectral Hounsfield unit (HU) curves and effective Z (atomic number) generated on dual-energy gemstone spectral imaging computed tomography (CT) in the differentiation of benign and malignant neck pathologic findings. METHODS: This was a retrospective review of 38 patients who underwent neck CT on a gemstone spectral imaging dual-energy CT (Lightspeed CT750 HD 64-slice CT scanner; GE Medical Systems, Milwaukee, Wis) from November 2009 to June 2012 with identifiable masses. One board-certified radiologist placed regions of interest within the mass (19 benign, 19 malignant) and in paraspinal muscles (PSMs) to create 2 spectral HU curves in each patient. The curve parameters compared between the benign and malignant groups included range (conceptually, the difference between the highest and lowest HU), asymptote, decay, and the differences and ratios (of lesion to PSM) of each of these 3 parameters. A logistic regression model was built with these parameters and effective Z. RESULTS: The difference in ranges (between lesion and PSM) was the best predictor of malignancy, with a threshold of 75 or greater demonstrating 95% sensitivity, 89% specificity, and 91.8% area under the curve (AUC). Adding other spectral HU parameters and effective Z to the model did not substantially increase the AUC (93.3%, difference between the 2 models not statistically significant, P > 0.25). The effective Z showed a 79.9% AUC with 68% sensitivity and 68% specificity at an 8.80 cutoff. CONCLUSIONS: The spectral HU curve is promising for differentiating benign and malignant neck pathologic findings, with the difference in range between the lesion and PSM showing the best predictive value.

Magnetic resonance imaging of a temporal lobe cerebral amyloidoma.

Amyloidomas are focal solitary amyloid masses without systemic involvement that have been observed to occur in various body locations. When presenting intracranially, they pose a challenging diagnostic and therapeutic course given their location and rarity. We report a case of a 62-year-old man with a 4-year history of seizure and headaches. Magnetic resonance imaging was initially inconclusive but revealed an ill-defined right temporal lobe lesion. Biopsy later confirmed a cerebral amyloidoma. We also review the current literature on the pathogenesis, imaging findings, prognosis, and treatment of cerebral amyloidomas.

Subdural hematoma prevalence and long-term developmental outcomes in patients with benign expansion of the subarachnoid spaces.

OBJECTIVE: Benign expansion of the subarachnoid spaces (BESS) is a condition seen in macrocephalic infants. BESS is associated with mild developmental delays which tend to resolve within a few years. It is accepted that patients with BESS are at increased risk of spontaneous subdural hematomas (SDHs), although the exact pathophysiology is not well understood. The prevalence of spontaneous SDH in BESS patients is poorly defined, with only a few large single-center series published. In this study the authors aimed to better define BESS prevalence and developmental outcomes through the longitudinal review of a large cohort of BESS patients. METHODS: A large retrospective review was performed at a single institution from 1995 to 2020 for patients 2 years of age or younger with a diagnosis of BESS by neurology or neurosurgery and head circumference > 85th percentile. Demographic data, head circumference, presence of developmental delay, occurrence of SDH, and need for surgery were extracted from patient charts. The subarachnoid space (SAS) size was measured from the available MR images, and the sizes of those who did and did not develop SDH were compared. RESULTS: Free text search revealed BESS mentioned within the medical records of 1410 of 2.6 million patients. After exclusion criteria, 480 patients remained eligible for the study. Thirty-two percent (n = 154) of patients were diagnosed with developmental delay, most commonly gross motor delay (53%). Gross motor delay resolved in 86% of patients at a mean age of 22.2 months. The prevalence of spontaneous SDH in this BESS population over a period of 25 years was 8.1%. There was no significant association between SAS size and SDH formation. CONCLUSIONS: This study represents results for one of the largest cohorts of patients with BESS at a single institution. Gross motor delay was the most common developmental delay diagnosed, and a majority of patients had resolution of their delay. These data support that children with BESS have a higher prevalence of SDH than the general pediatric population, although SAS size was not significantly associated with SDH development.

Contrast Pediatric Brain Perfusion: Dynamic Susceptibility Contrast and Dynamic Contrast-Enhanced MR Imaging.

Magnetic resonance (MR) perfusion is a robust imaging technique that assesses the passage of blood through the cerebral vascular network using a variety of techniques. The applications of MR perfusion have been expanded and is well suited to investigate cerebrovascular diseases and cerebral neoplastic processes in pediatric patients. Assessment of brain perfusion can augment the information obtained on conventional MR imaging and provides additional information on the biological and physiologic features of pediatric brain tumors. Similarly, MR perfusion can help guide the management of a variety of pediatric cerebrovascular diseases, including acute ischemic stroke and Moyamoya syndrome.

MRI evaluation of nerve root avulsion in neonatal brachial plexus palsy: understanding the presence of isolated dorsal/ventral rootlet disruption.

OBJECTIVE: The evaluation, treatment, and prognosis of neonatal brachial plexus palsy (NBPP) continues to have many areas of debate, including the use of ancillary testing. Given the continued improvement in imaging, it is important to revisit its utility. Nerve root avulsions have historically been identified by the presence of pseudomeningoceles or visible ruptures. This "all-or-none" definition of nerve root avulsions has many implications for the understanding and management of NBPP, especially as characterization of the proximal nerve root as a potential donor remains critical. This study examined the ability of high-resolution MRI to more specifically define the anatomy of nerve root avulsions by individually examining the ventral and dorsal rootlets as they exit the spinal cord. METHODS: This is a retrospective review of patients who had undergone brachial plexus protocol MRI for clinical evaluation of NBPP at a single institution. Each MR image was independently reviewed by a board-certified neuroradiologist, who was blinded to both established diagnosis/surgical findings and laterality. Each dorsal and ventral nerve rootlet bilaterally from C5 to T1 was evaluated from the spinal cord to its exit in the neuroforamen. Each rootlet was classified as avulsed, intact, or undeterminable. RESULTS: Sixty infants underwent brachial plexus protocol MRI from 2010 to 2018. All infants were included in this study. Six hundred individual rootlets were analyzed. There were 49 avulsed nerve rootlets in this cohort. Twenty-nine (59%) combined dorsal/ventral avulsions involved both the ventral and dorsal rootlets, and 20 (41%) were either isolated ventral or isolated dorsal rootlet avulsions. Of the isolated avulsion injuries, 13 (65%) were dorsal only, meaning that the motor rootlets were intact. CONCLUSIONS: A closer look at nerve root avulsions with MRI demonstrates a significant prevalence (approximately 41%) of isolated dorsal or ventral nerve rootlet disruptions. This finding implies that nerve roots previously labeled as "avulsed" but with only isolated dorsal (sensory) rootlet avulsion can yet provide donor fascicles in reconstruction strategies. A majority (99%) of the rootlets can be clearly visualized with MRI. These findings may significantly impact the clinical understanding of neonatal brachial plexus injury and its treatment.

Development and Assessment of a Model for Predicting Individualized Outcomes in Patients With Oropharyngeal Cancer.

Importance: Recent insights into the biologic characteristics and treatment of oropharyngeal cancer may help inform improvements in prognostic modeling. A bayesian multistate model incorporates sophisticated statistical techniques to provide individualized predictions of survival and recurrence outcomes for patients with newly diagnosed oropharyngeal cancer. Objective: To develop a model for individualized survival, locoregional recurrence, and distant metastasis prognostication for patients with newly diagnosed oropharyngeal cancer, incorporating clinical, oncologic, and imaging data. Design, Setting, and Participants: In this prognostic study, a data set was used comprising 840 patients with newly diagnosed oropharyngeal cancer treated at a National Cancer Institute-designated center between January 2003 and August 2016; analysis was performed between January 2019 and June 2020. Using these data, a bayesian multistate model was developed that can be used to obtain individualized predictions. The prognostic performance of the model was validated using data from 447 patients treated for oropharyngeal cancer at Erasmus Medical Center in the Netherlands. Exposures: Clinical/oncologic factors and imaging biomarkers collected at or before initiation of first-line therapy. Main Outcomes and Measures: Overall survival, locoregional recurrence, and distant metastasis after first-line cancer treatment. Results: Of the 840 patients included in the National Cancer Institute-designated center, 715 (85.1%) were men and 268 (31.9%) were current smokers. The Erasmus Medical Center cohort comprised 300 (67.1%) men, with 350 (78.3%) current smokers. Model predictions for 5-year overall survival demonstrated good discrimination, with area under the curve values of 0.81 for the model with and 0.78 for the model without imaging variables. Application of the model without imaging data in the independent Dutch validation cohort resulted in an area under the curve of 0.75. This model possesses good calibration and stratifies patients well in terms of likely outcomes among many competing events. Conclusions and Relevance: In this prognostic study, a multistate model of oropharyngeal cancer incorporating imaging biomarkers appeared to estimate and discriminate locoregional recurrence from distant metastases. Providing personalized predictions of multiple outcomes increases the information available for patients and clinicians. The web-based application designed in this study may serve as a useful tool for generating predictions and visualizing likely outcomes for a specific patient.

CT and FDG-PET radiologic biomarkers in p16+ oropharyngeal squamous cell carcinoma patients treated with definitive chemoradiotherapy.

PURPOSE: To assess associations between imaging biomarkers from standard of care pre-treatment CT and FDG-PET scans and locoregional (LR) and distant metastatic (DM) recurrences in patients with p16+ oropharyngeal squamous cell carcinoma (OPSCC) treated with definitive chemoradiotherapy (CRT). METHODS: An institutional database from a single NCI-designated cancer center identified 266 patients with p16+ OPSCC treated with definitive CRT in our department from 2005 to 2016 with evaluable pre-treatment FDG-PET scans. Quantitative SUV metrics and qualitative imaging metrics were determined from FDG-PET and CT scans, while clinical characteristics were abstracted from the medical record. Associations between clinical/imaging features and time to LR (TTLRF) or DM (TTDMF) failure and overall survival (OS) were assessed using univariable Cox regression and penalized stepwise regression for multivariable analyses (MVA). RESULTS: There were 27 LR and 32 DM recurrences as incident failures. Imaging biomarkers were significantly associated with TTLRF, TTDMF and OS. FDG-PET metrics outperformed CT and clinical metrics for TTLRF, with metabolic tumor volume being the only significant feature selected on MVA: C-index = 0.68 (p = 0.01). Radiographic extranodal extension (rENE), positive retropharyngeal nodes (RPN+), and clinical stage were significant on MVA for TTDMF: C-index = 0.84 (p < 0.001). rENE, group stage, and RPN+ were significant on MVA for OS: C-index = 0.77 (p < 0.001). CONCLUSIONS: In the largest study to date of uniformly treated patients with CRT to evaluate both pretreatment CT and FDG-PET, radiographic biomarkers were significantly associated with TTLRF, TTDMF and OS among patients with p16+ OPSCC treated with CRT. CT metrics performed best to predict TTDMF, while FDG-PET metrics showed improved prediction for LRRFS. These metrics may help identify candidates for treatment intensification or de-escalation of therapy. STATEMENT OF TRANSLATIONAL RELEVANCE: Pre-treatment imaging features from standard-of-care PET/CT imaging show promise for predicting long-term outcomes following HPV-associated oropharynx cancer (HPV-OPC) therapy. This study comprehensively characterizes qualitative and quantitative pre-treatment imaging metrics associated with time to pattern-specific failure in a cohort of 266 patients treated uniformly with definitive chemoradiation. Multivariate analysis (MVA) for time to locoregional failure (TTLRF), time to distant metastatic failure (TTDMF), and overall survival (OS) was performed. FDG-PET metrics outperformed CT and clinical metrics for TTLRF. CT radiographic extranodal extension, positive retropharyngeal nodes, and stage strongly predicted TTDMF (combined C-index = 0.84, log rank p < 0.001). Number of smoking pack-years complemented clinical and imaging features only in patients without radiographic extranodal extension or positive retropharyngeal nodes. Time to pattern-specific failure is important for guiding treatment de-escalation strategies, which intend to reduce treatment-related toxicity in patients with relatively long expected survival times. This study suggests that PET/CT features should play a crucial role in future de-escalation trials and management of HPV-OPC patients.

Congenital spine and spinal cord malformations--self-assessment module.

The educational objectives of this self-assessment module are for the participants to exercise, self-assess, and improve their understanding of the most important features of congenital spine and spinal cord malformations.

Head and neck cancers on CT: preliminary study of treatment response assessment based on computerized volume analysis.

OBJECTIVE: The objective of our study was to investigate the feasibility of computerized segmentation of lesions on head and neck CT scans and evaluate its potential for estimating changes in tumor volume in response to treatment of head and neck cancers. MATERIALS AND METHODS: Twenty-six CT scans were retrospectively collected from the files of 13 patients with 35 head and neck lesions. The CT scans were obtained from an examination performed before treatment (pretreatment scan) and an examination performed after one cycle of chemotherapy (posttreatment scan). Thirteen lesions were primary site cancers and 22 were metastatic lymph nodes. An experienced radiologist (radiologist 1) marked the 35 lesions and outlined each lesion's 2D contour on the best slice on both the pre- and posttreatment scans. Full 3D contours were also manually extracted for the 13 primary tumors. Another experienced radiologist (radiologist 2) verified and modified, if necessary, all manually drawn 2D and 3D contours. An in-house-developed computerized system performed 3D segmentation based on a level set model. RESULTS: The computer-estimated change in tumor volume and percentage change in tumor volume between the pre- and posttreatment scans achieved a high correlation (intraclass correlation coefficient [ICC] = 0.98 and 0.98, respectively) with the estimates from manual segmentation for the 13 primary tumors. The average error in estimating the percentage change in tumor volume by automatic segmentation relative to the radiologists' average error was -1.5% +/- 5.4% (SD). For the 35 lesions, the ICC between the automatic and manual estimates of change in pre- to posttreatment tumor area was 0.93 and of percentage change in pre- to posttreatment tumor area was 0.85. The average error in estimating the percentage change in tumor area by automatic segmentation was -3.2% +/- 15.3%. CONCLUSION: Preliminary results indicate that this computerized segmentation system can reliably estimate changes in tumor size on CT scans relative to radiologists' manual segmentation. This information can be used to calculate changes in tumor size on pre- and posttreatment scans to assess response to treatment.