Conventional Computed Tomography Scans Research Articles

Dual-Energy Computed Tomography Applications for the Evaluation of Cervical Lymphadenopathy.

There is recent interest in the use of dual-energy computed tomography (CT) in head and neck imaging, and the results are encouraging. This article reviews dual-energy CT applications as complementary tools to conventional CT scanning in the evaluation of cervical lymphadenopathy. The article cites the most relevant studies and highlights their results. Single-source and dual-source dual-energy applications including virtual noncontrast images, linear and nonlinear image blending, monochromatic images, iodine quantification, and spectral Hounsfield unit attenuation curve analysis are reviewed. Future directions and research suggestions are discussed in brief.

Simultaneous head and facial computed tomography scans for assessing facial fractures in patients with traumatic brain injury

IntroductionPatients with traumatic brain injury (TBI) may have concomitant facial fractures. While most head injury patients receive head computed tomography (CT) scans for initial evaluation, the objective of our study was to investigate the value of simultaneous facial CT scans in assessing facial fractures in patients with TBI. MethodsFrom January 1, 2015 to December 31, 2015, 1649 consecutive patients presenting to our emergency department (ED) with a TBI who received CT scans using the protocol for head and facial bones were enrolled. The clinical data and CT images were reviewed via a standardized format. ResultsIn our cohort, 200 patients (12.1%) had at least one facial fracture shown on the CT scans. Patients with facial fractures were more likely to have initial loss of consciousness (ILOC; p<0.001), a Glasgow coma scale of 8 or less (p<0.001), moderate or severe degrees of head injury severity scale (p<0.001), positive physical examination findings (p<0.001), and positive CT cranial abnormalities (p<0.001). A total of 166 (83.0%) patients with facial fractures required further facial CT scans instead of conventional head CT scans alone. Surgical intervention was mandatory in 73 (44.0%) of the 166 patients, who more frequently exhibited fractures of the lower third of the face (p<0.001) and orbital fractures (p=0.019). ConclusionsTBI patients with risk factors may have a higher probability of concomitant facial fractures. Fractures of the lower third of the face and orbit are easily overlooked in routine head CT scans but often require surgical intervention. Therefore, simultaneous head and facial CT scans are suggested in selected TBI patients.

Assessing Foraminal Stenosis in the Cervical Spine: A Comparison of Three-Dimensional Computed Tomographic Surface Reconstruction to Two-Dimensional Modalities.

Study Design:Retrospective radiographic study.Objective:The optimal radiographic modality for assessing cervical foraminal stenosis is unclear. Determination on conventional axial cuts is made difficult due in part to the complex, oblique orientation of the cervical neuroforamen. The utility of 3-dimensonal (3D) computed tomography (CT) reconstruction in improving neuroforaminal assessment is not well understood. The objective of this study is to determine inter-rater variability in grading cervical foraminal stenosis using 3 different CT imaging modalities: 3D CT surface reconstructions (3DSR), 2D sagittal oblique multiplanar reformations (2D-SOMPR), and conventional 2D axial CT imaging.Methods:Pretreatment CT scans of 25 patients undergoing surgery for cervical spondylotic radiculopathy were analyzed at 2 levels: C5-C6 and C6-C7. Simple interrater agreement and kappa-Fleiss coefficients were calculated for each imaging modality and stenosis grade. Image reviewers (attending spine surgeon, attending neuroradiologist, spine fellow) interpreted each CT scan in 3 different formats: axial, 2D-SOMPR, and 3DSR. Four cervical foramina at 2 spinal levels were graded as normal (no stenosis), mild (≤25% stenosis), moderate (25%-50% stenosis), or severe (>50% stenosis).Results:Across all imaging modalities, interrater reliability was fair when grading foraminal stenosis (κ < 0.4). Agreement was lowest for the axial images (κ = 0.119) and highest for the 3D CT reconstructions (κ = 0.334). 2D-SOMPR images also led to improved interrater reliability when compared with axial images (κ = 0.255).Conclusion:Grading cervical foraminal stenosis using conventional axial CT imaging is difficult with low interrater reliability. CT modalities that provide a circumferential view of the cervical foramen, such as 2D-SOMPR and 3D CT reconstruction, had higher rates of interobserver reliability in grading foraminal stenosis than conventional axial cuts, with 3D having the highest. As these 3D reconstructions can be obtained at no additional cost or radiation exposure over a conventional CT scan, and because they can provide useful information in determining levels being considered for surgical decompression, we recommend they be utilized when evaluating cervical foramina.

Measuring of Abdominal Aortic Aneurysm with Three-Dimensional Computed Tomography Reconstruction before Endovascular Aortic Aneurysm Repair.

PurposeConventional computed tomography (CT) is the gold standard method for case planning for endovascular aortic aneurysm repair (EVAR). However, aortography with a marking catheter is needed for measuring the actual length of an aneurysm. With advances in imaging technology, a 3-dimensional (3D) workstation can obviate the need for the aortography. The objective of this study was to determine whether a 3D workstation could obviate the need for aortography for EVAR.Materials and MethodsOne vascular surgeon and 1 interventional radiologist retrospectively assessed axial CT scans and reformatted the 3D CT scans by using the iNtuition workstation (TeraRecon Inc., San Mateo, CA, USA) for 25 patients who underwent EVAR. Four measurements of diameter and length were obtained from each modality. The actual length of an aneurysm for the proper graft was decided by 2 observers by reviewing the aortography with a marking catheter.ResultsThe measurements from the 2 modalities were reproducible with intraobserver correlation coefficients of 0.89 to 1.0 for conventional CT and 0.98 to 1.0 for 3D workstation. Interobserver correlation coefficients were 0.29 to 0.95 for conventional CT and 0.85 to 0.99 for the 3D workstation. The length of the aneurysm for proper main graft coincided in 18 and 14 patients according to the conventional CT scan and in 21 and 18 patients according to the 3D workstation, respectively.ConclusionThe interobserver agreement in planning EVAR was significantly better with the iNtuition 3D workstation. But aortography with a marking catheter may still be needed for selecting the proper graft.

Validation and accuracy of intraoperative CT scan using the Philips AlluraXper FD20 angiography suite for assessment of spinal instrumentation

Background: With the concept of the hybrid operating room gaining popularity, the authors adapted a hybrid angiographic suite with intraoperative computed tomography (iCT) to evaluate accuracy of pedicle screw placement in spinal fusion. This retrospective review examines how well iCT detected extrapedicular screw violation, to then allow repositioning and potentially avoid revision surgery.Methods: A total of 36 consecutive patients underwent pedicle screw placement in posterior cervical, thoracic, and lumbosacral spinal fusions. All patients underwent iCT in the Philips AlluraXper FD20 angiography suite in the lumbar spine XperCT mode and postoperative conventional computed tomography (CT) scanning. Primary endpoints included the sensitivity and specificity of iCT in detecting pedicular violation characterized as minor, moderate, or severe when compared with postoperative CT. Secondary endpoint included the incidence of replaced screws during surgery and number of revision surgeries.Results: Of 241 screws placed in 16 males and 20 females, iCT detected severe pedicle violation in 25 screws (10.4%); 16 screws were then repositioned during surgery. Sensitivity and specificity of iCT to detect severe screw malposition were 92.3% and 99.1%, respectively. No revision surgeries were performed in this series.Conclusions: In our series, iCT had high sensitivity and specificity in detecting severe screw malposition. As a valuable adjunct for intraoperative assessment of pedicle screw position, immediate intraoperative correction of misplaced screws then eliminated any revision surgery for our patients.

Radiolucent Skull Clamps for Intra-Operative Imaging: A Technical Note.

Conventionally, surgery and procedural-based radiology are performed on different premises. With advances in imaging technology, the operating room is rapidly being transformed into an intraoperative imaging suite. Diagnostic imaging in conjunction with surgery has great utility and by all accounts has great future potential. During the last decade, cone beam computed tomography (CT) scanners have been introduced and have made intraoperative imaging more feasible because these scanners can be made less bulky. The current usefulness of intraoperative magnetic resonance imaging (MRI) or CT for neurosurgery, however, is impaired by the lack of completely radiolucent skull clamps, causing image artifacts. Metal artifacts are particularly problematic, given that they lead to a considerably higher image quality degradation factor for cone beam CT scanners than for conventional CT scanners. Here, we describe our experience with near-radiolucent skull clamps and their associated problems and discuss future improvements to facilitate high-quality image guidance in the field of neurosurgery.

Development of a prototype chest digital tomosynthesis (CDT) R/F system with fast image reconstruction using graphics processing unit (GPU) programming

Digital tomosynthesis offers the advantage of low radiation doses compared to conventional computed tomography (CT) by utilizing small numbers of projections (~80) acquired over a limited angular range. It produces 3D volumetric data, although there are artifacts due to incomplete sampling. Based upon these characteristics, we developed a prototype digital tomosynthesis R/F system for applications in chest imaging. Our prototype chest digital tomosynthesis (CDT) R/F system contains an X-ray tube with high power R/F pulse generator, flat-panel detector, R/F table, electromechanical radiographic subsystems including a precise motor controller, and a reconstruction server. For image reconstruction, users select between analytic and iterative reconstruction methods. Our reconstructed images of Catphan700 and LUNGMAN phantoms clearly and rapidly described the internal structures of phantoms using graphics processing unit (GPU) programming. Contrast-to-noise ratio (CNR) values of the CTP682 module of Catphan700 were higher in images using a simultaneous algebraic reconstruction technique (SART) than in those using filtered back-projection (FBP) for all materials by factors of 2.60, 3.78, 5.50, 2.30, 3.70, and 2.52 for air, lung foam, low density polyethylene (LDPE), Delrin® (acetal homopolymer resin), bone 50% (hydroxyapatite), and Teflon, respectively. Total elapsed times for producing 3D volume were 2.92s and 86.29s on average for FBP and SART (20 iterations), respectively. The times required for reconstruction were clinically feasible. Moreover, the total radiation dose from our system (5.68mGy) was lower than that of conventional chest CT scan. Consequently, our prototype tomosynthesis R/F system represents an important advance in digital tomosynthesis applications.

Comparison of a Novel Weightbearing Cone Beam Computed Tomography Scanner Versus a Conventional Computed Tomography Scanner for Measuring Patellar Instability.

Background:Conventional computed tomography (CT) images are routinely used for diagnosing patellofemoral instability and are obtained with the patient in a supine position, nonweightbearing, with the knee in full extension, and with leg muscles relaxed. A new portable extremity cone beam CT (CBCT) scanner has been developed that may allow for more accurate diagnosis, as imaging can be performed with the patient standing, the knee flexed, and with leg muscles active.Purpose/Hypothesis:The purpose of this study was to compare CT measurements of patellar alignment on a prototype scanner versus conventional scanner in patients with known patellar instability. The hypothesis was that the measurements obtained with the knee flexed and the patient weightbearing would be less than those obtained from the conventional CT scan.Study Design:Cross-sectional study; Level of evidence, 3.Methods:Twenty patients with a diagnosis of lateral patellar instability were imaged on both a conventional CT scanner and on a prototype CBCT scanner. Objective measures of patellofemoral alignment (tilt angle, congruence angle, tibial tuberosity–trochlear groove [TT-TG] offset) were assessed on images obtained from the prototype and conventional CT scans by 2 independent reviewers. Paired t tests were calculated to compare the mean measurement of patellofemoral alignment obtained from the prototype versus conventional CT. Interrater reliability was assessed using a 2-way mixed-effects model intraclass correlation coefficient (ICC) for tilt angle, congruence angle, and TT-TG offset on the prototype and conventional CT scans.Results:Measurements of patellofemoral alignment were significantly less when acquired by the new prototype CBCT scanner while subjects were weightbearing on a flexed knee. On the images from the prototype CBCT scan, the tilt angle averaged 18.2° ± 11.6° compared with 28.1° ± 7.1° on the conventional CT scan (P < .0001). The congruence angle was 3.0° ± 30.1° compared with 26.7° ± 18.1° on the conventional CT scan (P = .0002). Finally, the TT-TG offset distance averaged 12.3 ± 6.3 mm when measured on the CBCT scan compared with 20.1 ± 4.2 mm on the conventional CT scan (P < .0001). Good interrater reliability was found for tilt angle, congruence angle, and TT-TG offset on conventional and CBCT scans (ICC range, 0.79-0.96).Conclusion:In patients with patellar instability, measurements of patellofemoral alignment are reduced on images obtained from a new weightbearing extremity CBCT scanner on a flexed knee versus conventional CT in the supine position with a fully extended knee. Improvement in objective measurements of patellar alignment should lead to improved clinical and surgical care of patients with this condition.

Creation of an idealized nasopharynx geometry for accurate computational fluid dynamics simulations of nasal airflow in patient-specific models lacking the nasopharynx anatomy.

Virtual surgery planning based on computational fluid dynamics (CFD) simulations has the potential to improve surgical outcomes for nasal airway obstruction patients, but the benefits of virtual surgery planning must outweigh the risks of radiation exposure. Cone beam computed tomography (CT) scans represent an attractive imaging modality for virtual surgery planning due to lower costs and lower radiation exposures compared with conventional CT scans. However, to minimize the radiation exposure, the cone beam CT sinusitis protocol sometimes images only the nasal cavity, excluding the nasopharynx. The goal of this study was to develop an idealized nasopharynx geometry for accurate representation of outlet boundary conditions when the nasopharynx geometry is unavailable. Anatomically accurate models of the nasopharynx created from 30 CT scans were intersected with planes rotated at different angles to obtain an average geometry. Cross sections of the idealized nasopharynx were approximated as ellipses with cross-sectional areas and aspect ratios equal to the average in the actual patient-specific models. CFD simulations were performed to investigate whether nasal airflow patterns were affected when the CT-based nasopharynx was replaced by the idealized nasopharynx in 10 nasal airway obstruction patients. Despite the simple form of the idealized geometry, all biophysical variables (nasal resistance, airflow rate, and heat fluxes) were very similar in the idealized vs patient-specific models. The results confirmed the expectation that the nasopharynx geometry has a minimal effect in the nasal airflow patterns during inspiration. The idealized nasopharynx geometry will be useful in future CFD studies of nasal airflow based on medical images that exclude the nasopharynx.

Reliability and Validity of Lower Extremity Computed Tomography as a Screening Tool for Osteoporosis

Category: Ankle Introduction/Purpose: Although previous studies have demonstrated the potential of conventional computed tomography (CT) as a screening tool for osteoporosis, the assessment correlation of BMD in those studies was limited to the spine. This study aimed to evaluate the reliability and validity of CT as a screening tool for osteoporosis and to estimate the correlation between central BMD and peripheral bone attenuation using lower extremity CT. Methods: In total, 292 patients who underwent a lower extremity, lumbar spine, or abdomen and pelvic CT scan within a 3- month interval of a dual-energy X-ray absorptiometry (DEXA) examination were included (Fig 1). Following reliability testing, bone attenuation of the L1, L2, L3, L4, femoral head, femoral neck, greater trochanter, distal femur, proximal tibia, distal tibia, and talus was measured by placing a circular region of interest on the central part of each bony region on a coronal CT image (Fig 2 and 3). Partial correlation was used to assess the correlation between CT and DEXA, after adjusting for age and body mass index. Results: In terms of reliability, all bone attenuation measurements, except the femoral neck, showed good to excellent interobserver reliability (intraclass correlation coefficients, 0.691–0.941). In terms of validity, bone attenuation of the L1 to L4, femoral neck, and greater trochanter on CT showed significant correlations with BMD of each area on DEXA (correlation coefficients, 0.399–0.613). Bone attenuation of the distal tibia and talus on CT showed significant correlations with BMD of all parts on DEXA (correlation coefficients, 0.493–0.581 for distal tibia, 0.396–0.579 for talus). Conclusion: Lower extremity CT is a useful screening tool for osteoporosis, and peripheral bone attenuation on lower extremity CT adequately reflects central BMD on DEXA.

Differential diagnosis of solitary pulmonary nodules with dual-source spiral computed tomography.

The aim of the present study was to analyze the value of applying dual-source 64-layer spiral computed tomography (CT) in the differential diagnosis of solitary pulmonary nodules (SPNs). Mediastinal windows from 45 cases were selected to study SPNs (maximum diameter, ≤3 cm), and the pathological nature of lesions was determined by clinical and pathological diagnosis. Conventional 64-layer spiral CT scanning, local enhancement and 3D recombination technologies were used to determine the occurrence rate, lesion diameter, degree of enhancement, lobular sign, spicule sign, pleural indentation sign, vessel convergence sign and bronchus sign. The final diagnoses indicated 34 cases of malignant SPNs (75.6%) and 11 benign cases (24.4%). When the nodule diameter in the malignant group was compared with that of the benign group, the difference was not statistically significant (P>0.05). Nodules in the malignant group showed inhomogeneous enhancement while nodules in the benign group showed homogeneous enhancement. The enhanced CT values in the malignant group were higher than those in the benign group, and the difference was statistically significant (P<0.05). The proportion of nodules with lobular sign in the malignant group was significantly higher than that in the benign group (P<0.05). The proportion of nodules with calcification, vessel convergence sign and bronchus sign in the malignant group were significantly higher than those in the benign group, and the differences were statistically significant (P<0.05). A comparison of vacuole sign, pleural indentation sign, spiculate protuberance and fat occurrence between the two groups yielded no statistically significant differences (P>0.05). The sensitivity of CT enhancement was 85.6%, specificity was 79.6%, positive predicated value was 92.3%, and the negative predicted value was 85.2%. In conclusion, SPNs diagnosed by CT enhancement manifested with enhancement degree, lobular sign, calcification, vessel convergence sign and bronchus sign with high diagnostic accuracy.

Role of FDG-PET scan in the management of pediatric mature B cell non-Hodgkin’s lymphoma. CCHE experience

Aim of workTo evaluate the sensitivity (Se), specificity (Sp), and predictive values (PV) of PET scan during management of pediatric mature B cell non-Hodgkin’s lymphoma (NHL) in comparison with conventional computed tomography (CT) scan. Patients and methodsA retrospective study enrolled on pediatric NHL patients at Children Cancer Hospital Egypt (CCHE) during the period from July 2007 to the end of June 2013. ResultsFor 115 pediatric patients diagnosed with mature B cell NHL, 152 PET and 152 CT scans were done simultaneously. Median age was 5.7years. They were 85 males (74%) and 30 females (26%). One hundred twenty six scans (82.9%) were done for 100 (87%) Burkitt lymphoma (BL) patients, while 26 scans (17.1%) were done for 15 (13.0%) patients with diffuse large B cell NHL (DLBC). Nineteen examination (12.5%) were done before starting chemotherapy (group 1), 107 (70.3%) at time of evaluation (group 2), and 26 (17.1%) during follow up (group C). Overall sensitivity was 91.6% for PET and 70.0% for conventional CT (p=0.02). Specificity was 84.1% for PET and 58.9% for CT (p<0.001). Positive predictive value (PPV) for PET was 50%, while was 22% for CT scan (p<0.001). Negative predictive value (NPV) for PET was 98%, and 92% for CT (p=0.01). ConclusionPET scan is significantly more sensitive than conventional CT in the management of aggressive pediatric mature B cell NHL. PET negativity is an excellent indicator of tumor response.

Dual-Energy CT-based Display of Bone Marrow Edema in Osteoporotic Vertebral Compression Fractures: Impact on Diagnostic Accuracy of Radiologists with Varying Levels of Experience in Correlation to MR Imaging.

Purpose To evaluate whether a dual-energy (DE) computed tomographic (CT) virtual noncalcium technique can improve the detection rate of acute thoracolumbar vertebral compression fractures in patients with osteoporosis compared with that at magnetic resonance (MR) imaging depending on the level of experience of the reading radiologist. Materials and Methods This retrospective study was approved by the institutional ethics committee. Informed consent was obtained from all patients. Forty-nine patients with osteoporosis who were suspected of having acute vertebral fracture underwent DE CT and MR imaging. Conventional linear-blended CT scans and corresponding virtual noncalcium reconstructions were obtained. Five radiologists with varying levels of experience evaluated gray-scale CT scans for the presence of fractures and their suspected age. Then, virtual noncalcium images were evaluated to detect bone marrow edema. Findings were compared with those from MR imaging (the standard of reference). Sensitivity and specificity analyses for diagnostic performance and matched pair analyses were performed on vertebral fracture and patient levels. Results Sixty-two fractures were classified as fresh and 52 as old at MR imaging. The diagnostic performance of all readers in the detection of fresh fractures improved with the addition of virtual noncalcium reconstructions compared with that with conventional CT alone. Although the diagnostic accuracy of the least experienced reader with virtual noncalcium CT (accuracy with CT alone, 61%; accuracy with virtual noncalcium technique, 83%) was within the range of that of the most experienced reader with CT alone, the latter improved his accuracy with the noncalcium technique (from 81% to 95%), coming close to that with MR imaging. The number of vertebrae rated as unclear decreased by 59%-90% or from 15-53 to 2-13 in absolute numbers across readers. The number of patients potentially referred to MR imaging decreased by 36%-87% (from 11-23 to 2-10 patients). Considering the gain in true decisions with the virtual noncalcium technique on a patient level, between 12 (most experienced reader) and 17 (least experienced reader) MR examinations could have been avoided. Conclusion The DE CT-based virtual noncalcium technique may enable depiction of bone marrow edema in thoracolumbar vertebral compression fractures in patients with osteoporosis, with good accordance with MR imaging when images are read by experienced radiologists. Although less experienced readers improved their diagnostic performance to some degree, the experienced reader's diagnostic performance approached that with MR imaging. (©) RSNA, 2016.

Preoperative Evaluation for Pelvic Discontinuity Using a New Reformatted Computed Tomography Scan Protocol

BackgroundThe identification of suspected pelvic discontinuity is important for preoperative planning in revision hip arthroplasty. Computed tomography (CT) of the pelvis with reconstructions in the axial, sagittal, and coronal planes has been previously described for the identification of pelvic discontinuity but fails to show some discontinuities. The purpose of this study was to determine whether reformatted 45° oblique CT scans of the pelvis, similar in projection to Judet views on plain films, provide advantages in detecting pelvic discontinuity preoperatively over standard reconstruction CT scans. We describe a new technique of reformatting conventional CT scans to present 45° oblique views of the pelvis. MethodsUsing an institutional joint registry, we retrospectively identified 22 patients who had intraoperative findings of pelvic discontinuity and also had a preoperative CT scan of the pelvis. The criterion for diagnosis of pelvic discontinuity was a continuous visible fracture line involving the entire width of the anterior and posterior columns. ResultsIn this study, standard reconstruction CT scans were 73% sensitive in identifying discontinuity based on these parameters and the addition of reformatted 45° oblique CT scans increased sensitivity to 91%. ConclusionUnique reconstructive techniques in revision hip arthroplasty can be used, and the operative plan may be modified if pelvic discontinuity is identified preoperatively. CT scans of the pelvis with reconstructions at 45° iliac oblique and obturator oblique views in patients with suspected pelvic discontinuity provide a high level of sensitivity when the diagnosis cannot be firmly established from plain films.

Comparison of Conventional Versus Spiral Computed Tomography with Three Dimensional Reconstruction in Chronic Otitis Media with Ossicular Chain Destruction.

Background:Chronic otitis media (COM) can be treated with tympanoplasty with or without mastoidectomy. In patients who have undergone middle ear surgery, three-dimensional spiral computed tomography (CT) scan plays an important role in optimizing surgical planning.Objectives:This study was performed to compare the findings of three-dimensional reconstructed spiral and conventional CT scan of ossicular chain study in patients with COM.Patients and Methods:Fifty patients enrolled in the study underwent plane and three dimensional CT scan (PHILIPS-MX 8000). Ossicles changes, mastoid cavity, tympanic cavity, and presence of cholesteatoma were evaluated. Results of the two methods were then compared and interpreted by a radiologist, recorded in questionnaires, and analyzed. Logistic regression test and Kappa coefficient of agreement were used for statistical analyses.Results:Sixty two ears with COM were found in physical examination. A significant difference was observed between the findings of the two methods in ossicle erosion (11.3% in conventional CT vs. 37.1% in spiral CT, P = 0.0001), decrease of mastoid air cells (82.3% in conventional CT vs. 93.5% in spiral CT, P = 0.001), and tympanic cavity opacity (12.9% in conventional CT vs. 40.3% in spiral CT, P=0.0001). No significant difference was observed between the findings of the two methods in ossicle destruction (6.5% conventional CT vs. 56.4% in spiral CT, P = 0.125), and presence of cholesteatoma (3.2% in conventional CT vs. 42% in spiral CT, P = 0.172). In this study, spiral CT scan demonstrated ossicle dislocation in 9.6%, decrease of mastoid air cells in 4.8%, and decrease of volume in the tympanic cavity in 1.6%; whereas, none of these findings were reported in the patients' conventional CT scans.Conclusion:Spiral-CT scan is superior to conventional CT in the diagnosis of lesions in COM before operation. It can be used for detailed evaluation of ossicular chain in such patients.

Prevalence of High-Riding Vertebral Artery and Morphometry of C2 Pedicles Using a Novel Computed Tomography Reconstruction Technique.

Study DesignCross-sectional, matched-pair comparative study.PurposeTo determine whether a thin-sliced pedicular-oriented computed tomography (TPCT) scan reconstructed from an existing conventional computed tomography (CCT) scan is more accurate for identifying vertebral artery groove (VAG) anomalies than CCT.Overview of LiteraturePosterior atlantoaxial transarticular screw fixation and C2 pedicle screws can cause vertebral artery (VA) injury. Two anatomic variations of VAG anomalies are associated with VA injury: a high-riding VA (HRVA) and a narrow pedicle of the C2 vertebra. CCT scan is a reliable method used to evaluate VAG anomalies; however, its accuracy level remains debatable. Literature comparing the prevalence of C2 VAG anomalies between CCT and TPCT is limited.MethodsA total of 200 computed tomography scans of the upper cervical spine obtained between January 2008 and December 2011 were evaluated for C2 VAG anomalies (HRVA and narrow pedicular width) using CCT and TPCT. The prevalence of C2 VAG anomalies was compared using these two different measurement methods via a McNemar's test.ResultsOf the 200 patients studied, 23 HRVA (6.01%; 95% confidence interval [CI], 3.61%–8.39%) were detected with CCT, whereas 66 HRVA (16.54%; 95% CI, 12.85%–20.23%) were detected with TPCT (p<0.001). Sixty-two narrow pedicles (15.58%; 95% CI, 11.99%–19.15%) were detected with CCT, whereas 90 narrow pedicles (22.83%; 95% CI, 18.58%–26.87%) were detected with TPCT (p<0.001).ConclusionsVAG anomalies are commonly observed. A preoperative evaluation using TPCT reconstructed from an existing CCT revealed a significantly higher prevalence of C2 VAG anomalies than did CCT and showed comparable prevalence to previously published studies using more sophisticated and higher risk techniques. Therefore, we propose TPCT as an alternative preoperative evaluation for C2 screw placement and trajectory planning.

Comparison of a novel weight bearing cone beam computed tomography (CT) scanner versus a conventional CT scanner for measuring

Comparison of a novel weight bearing cone beam computed tomography (CT) scanner versus a conventional CT scanner for measuring

Bedside computed tomography in traumatic brain injury: Experience of 10,000 consecutive cases in neurosurgery at a level 1 trauma center in India.

Patients with traumatic brain injury (TBI) need frequent computed tomography (CT) of the head for assessment and management. In view of the associated polytrauma, hemodynamic instability, and various in-dwelling catheters and tubes, shifting of patients for CT scans may be difficult. To assess the role of mobile CT (Ceretom®; NeuroLogica Corporation, Boston, MA, USA) in a trauma center with respect to patient management. In this retrospective study over 67 months (June 2009 to January 2015), the number of CT scans done, the time taken for CT and downtime were evaluated. Also, for the first 1000 mobile CT scans, the clinical and radiological records of all patients with TBI who underwent imaging using the mobile CT scanner in the intensive care units (ICUs) were analyzed. A total of 10,000 mobile CT scans were done on the mobile CT scanner till January 5, 2015. Of the first 1000 patients evaluated, 75.3% had severe TBI, 15.1% had moderate TBI, and 9.6% had mild TBI. 78.1% patients were on ventilator, with 80.2% requiring sedation and 8.4%, an inotropic support. An in situ intracranial pressure monitoring was present in 21.1% of patients. In all, 12.4% of patients had long-bone fractures requiring skeletal traction; and, the tube thoracostomy was in-situ in 7.4%. No adverse events related to line malfunction/pullout occurred. The mean time for the performance of imaging using the mobile CT scan was 11.6 minutes compared with 47.8 minutes when patients were shifted to a conventional CT scan suite. The machine was nonfunctional 94 times, with an average downtime of 4.2 hours (range 2-72 hours). The life-cycle cost per mobile CT scan was Rs. 1340. A mobile CT has considerably changed the management response time in the neurosurgical intensive care unit (ICU) setup and decreased patient transfer times and the associated complications. Inclusion of a mobile CT scanner in the armamentarium of a neurosurgeon as a "bedside tool" can dramatically change decision making and the response time. It should be considered as the standard of care in any large-volume emergency department or neurosurgical facility.

Reperfusion-Related Intracerebral Hemorrhage.

The efficacy of intravenous thrombolysis (IVT) for acute ischemic stroke patients has been well established worldwide, with endovascular therapy performed in patients who have failed or are ineligible for IVT and who have major vessel occlusion. The most feared complication of acute stroke reperfusion therapy is intracerebral hemorrhage (ICH), as these patients have a poor clinical outcome and high mortality. The fundamental mechanisms responsible for reperfusion-related ICH include increased permeability and disruption of the blood-brain barrier. Recombinant tissue plasminogen activator may exacerbate the blood-brain barrier disruption through its pharmacological action during IVT. Furthermore, interactions between the device and the vessel walls and contrast intoxication may also be related to ICH, which includes the occurrence of subarachnoid hemorrhage after endovascular therapy. Numerous factors have been reported to be associated with or to be able to predict ICH, and several scoring systems have been developed for predicting symptomatic ICH (sICH) after IVT. However, a scoring system with enough power to detect an unacceptably high risk of sICH or to provide information on when to withdraw IVT has yet to be definitively established. In current clinical practice, acute stroke patients without contraindications for IVT who have been identified by conventional computed tomography scans normally undergo IVT, irrespective of any clinical predictors of ICH after IVT. Strategies that have been suggested for preventing reperfusion-related ICH in high-risk patients include intensive blood pressure control, tight glycemic control, and the avoidance of early aggressive antithrombotic therapy. If sICH, and especially massive parenchymal hematoma, does occur, hematoma expansion needs to be prevented through the use of tight blood pressure control and other methods. Although evidence of efficacy has yet to be established, surgical removal is performed not only for the purpose of saving lives but also for improving the functional outcome. In order to develop therapeutic strategies for reperfusion-related ICH that will lead to an improved stroke prognosis, further studies are warranted.

Radiation dose measurements of an on-board imager X-ray unit using optically-stimulated luminescence dosimeters.

Cone beam computed tomography (CBCT) is now widely used to image radiotherapy patients prior to treatment for the purpose of accurate patient setup. However each CBCT image delivered to a patient increases the total radiation dose that they receive. The measurement of the dose delivered from the CBCT images is not readily performed in the clinic. In this study, we have used commercially available optically stimulated luminescence (OSLD) dosimeters to measure the dose delivered by the Varian OBI on a radiotherapy linear accelerator. Calibration of the OSLDs was achieved by using a therapeutic X-ray unit. The dose delivered by a head CBCT scan was found to be 3.2 ± 0.3 mGy which is similar in magnitude to the dose of a head computed tomography (CT) scan. The results of this study suggest that the radiation hazard associated with CBCT is of a similar nature to that of conventional CT scans. We have also demonstrated that the OSLDs are suitable for these low X-ray dose measurements.