Mohannad Ibrahim

Prevalence of pineal cysts in children and young adults. Clinical article.

OBJECT Pineal cysts are a frequent incidental finding on intracranial imaging. In adults, the prevalence of pineal cysts is estimated to be 1.1-4.3%. However, the prevalence is not well established in younger patients. METHODS The authors retrospectively reviewed a consecutive series of 14,516 patients 25 years of age and younger, who underwent brain MR imaging at a single institution over an 11-year period. In patients identified with pineal cysts, the authors analyzed the images according to cyst size, signal characteristics, enhancement pattern, and evidence of local mass effect. Patient characteristics including demographics and other intracranial diagnoses were collected in the pineal cyst population and compared with a randomly selected age- and sex-matched control patient population. The data were evaluated using univariate and multivariate logistic regression, linear regression, and ANOVA. RESULTS The authors identified 288 pineal region cysts (2.0%). The prevalence of pineal cysts was higher in female (2.4%) than in male patients (1.5%; p < 0.001). Pineal cysts were identified in patients of all ages, with an increased prevalence found in older patients (p < 0.001). Pineal cyst size was similar for all age and sex groups. CONCLUSIONS Pineal cysts are common in the pediatric population, with an increased prevalence in girls and in older patients.

Matted nodes: Poor prognostic marker in oropharyngeal squamous cell carcinoma independent of HPV and EGFR status

Despite better prognosis, there is a group of oropharyngeal squamous cell carcinoma (SCC) human papillomavirus (HPV)+ patients who experience treatment failure and succumb to distant metastasis.

Refining Risk Stratification for Locoregional Failure after Chemoradiotherapy in Human Papillomavirus-Associated Oropharyngeal Cancer

BACKGROUND To determine whether the addition of molecular and imaging biomarkers to established clinical risk factors could help predict locoregional failure (LRF) after chemoradiation in human papillomavirus (HPV)-related (+) oropharyngeal cancer (OPC) and improve patient selection for locoregional treatment de-intensification. METHODS HPV status was determined for 198 consecutive patients with stage III/IV OPC treated with definitive chemoradiation from 5/2003 to 10/2010. The impact of pre-therapy epidermal growth factor receptor (EGFR) overexpression; imaging biomarkers including primary tumor and nodal maximum standardized uptake values on FDG-PET, gross tumor volumes, and matted nodes; and clinical factors on LRF (including residual disease at adjuvant neck dissection) was assessed. RESULTS Primary tumors were HPV+ in 184 patients and HPV-negative in 14. EGFR overexpression was related to HPV-negative status and was univariately associated with LRF in the overall population, but was neither retained in the multivariate model after adjustment for HPV status, nor associated with LRF in HPV+ patients. Similarly, imaging biomarkers were univariately associated with LRF, but correlated with T-stage and/or N-stage and did not remain predictive in HPV+ patients after adjustment for T4- and N3-stages, which were the only significant predictors of LRF on multivariate analysis. Among HPV+ patients with non-T4- or N3-stages, only minimal smoking was associated with decreased LRF. CONCLUSIONS The prognostic impact of EGFR overexpression and imaging biomarkers on LRF was predominantly related to their association with HPV-negative status and T- or N-stage, respectively. Among HPV+ OPC patients treated with uniform chemoradiation, only T4-stage, N3-stage, and smoking contributed to risk-stratification for LRF.

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.

Congenital spine and spinal cord malformations--pictorial review.

Congenital abnormalities of the spine and spinal cord are referred to as spinal dysraphisms. This article reviews normal embryological development of the spine and spinal cord and the imaging findings of congenital abnormalities of the spine and spinal cord with particular focus on MRI.

Automated volume analysis of head and neck lesions on CT scans using 3D level set segmentation

The authors have developed a semiautomatic system for segmentation of a diverse set of lesions in head and neck CT scans. The system takes as input an approximate bounding box, and uses a multistage level set to perform the final segmentation. A data set consisting of 69 lesions marked on 33 scans from 23 patients was used to evaluate the performance of the system. The contours from automatic segmentation were compared to both 2D and 3D gold standard contours manually drawn by three experienced radiologists. Three performance metric measures were used for the comparison. In addition, a radiologist provided quality ratings on a 1 to 10 scale for all of the automatic segmentations. For this pilot study, the authors observed that the differences between the automatic and gold standard contours were larger than the interobserver differences. However, the system performed comparably to the radiologists, achieving an average area intersection ratio of 85.4% compared to an average of 91.2% between two radiologists. The average absolute area error was 21.1% compared to 10.8%, and the average 2D distance was 1.38 mm compared to 0.84 mm between the radiologists. In addition, the quality rating data showed that, despite the very lax assumptions made on the lesion characteristics in designing the system, the automatic contours approximated many of the lesions very well.

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.

Prevalence and natural history of pineal cysts in adults

OBJECT We reviewed our experience with pineal cysts to define the natural history and clinical relevance of this common intracranial finding. METHODS The study population consisted of 48,417 consecutive patients who underwent brain MR imaging at a single institution over a 12-year interval and who were over 18 years of age at the time of imaging. Patient characteristics, including demographic data and other intracranial diagnoses, were collected from cases involving patients with a pineal cyst. We then identified all patients with pineal cysts who had been clinically evaluated at our institution and who had at least 6 months of clinical and imaging follow-up. All inclusion criteria for the natural history analysis were met in 151 patients. RESULTS Pineal cysts measuring 5 mm or larger in greatest dimension were found in 478 patients (1.0%). Of these, 162 patients were male and 316 were female. On follow-up MR imaging of 151 patients with pineal cyst at a mean interval of 3.4 years from the initial study, 124 pineal cysts remained stable, 4 increased in size, and 23 decreased in size. Cysts that were larger at the time of initial diagnosis were more likely to decrease in size over the follow-up interval (p = 0.004). Patient sex, patient age at diagnosis, and the presence of septations within the cyst were not significantly associated with cyst change on follow-up. CONCLUSIONS Follow-up imaging and neurosurgical evaluation are not mandatory for adults with asymptomatic pineal cysts.

Skin cancer of the head and neck with perineural invasion: defining the clinical target volumes based on the pattern of failure.

PURPOSE To analyze patterns of failure in patients with head-and-neck cutaneous squamous cell carcinoma (HNCSCC) and clinical/radiologic evidence of perineural invasion (CPNI), in order to define neural clinical target volume (CTV) for treatment planning. METHODS AND MATERIALS Patients treated with three-dimensional (3D) conformal or intensity-modulated radiotherapy (IMRT) for HNCSCC with CPNI were included in the study. A retrospective review of the clinical charts, radiotherapy (RT) plans and radiologic studies has been conducted. RESULTS Eleven consecutive patients with HNCSCCs with CPNI were treated from 2000 through 2007. Most patients underwent multiple surgical procedures and RT courses. The most prevalent failure pattern was along cranial nerves (CNs), and multiple CNs were ultimately involved in the majority of cases. In all cases the involved CNs at recurrence were the main nerves innervating the primary tumor sites, as well as their major communicating nerves. We have found several distinct patterns of disease spread along specific CNs depending on the skin regions harboring the primary tumors, including multiple branches of CN V and VII. These patterns and the pertinent anatomy are detailed in the this article. CONCLUSIONS Predictable disease spread patterns along cranial nerves supplying the primary tumor sites were found in this study. Awareness of these patterns, as well as knowledge of the relevant cranial nerve anatomy, should be the basis for CTV definition and delineation for RT treatment planning.

Patterns of Nodal Metastasis and Prognosis in Human Papillomavirus Positive Oropharyngeal Squamous Cell Carcinoma

The current American Joint Committee on Cancer (AJCC) staging system may not accurately reflect survival in patients with human papillomavirus (HPV)‐positive oropharyngeal squamous cell carcinoma (SCC). The purpose of this study was to develop a system that more precisely predicts survival.