Head Computed Tomography Imaging Research Articles

Automated Segmentation of Head Computed Tomography Images Using FSL.

The aim of this study was to investigate the use of one magnetic resonance image-processing tool, FSL, in its ability to perform automated segmentation of computed tomographic images of the brain. Head computed tomography (CT) images were brain extracted and segmented using the FSL tools BET and FAST, respectively. The products of segmentation were analyzed by histogram. The impact of image intensity inhomogeneity correction was investigated using simulated bias fields, 14 routine head CT scans, and selected illustrative clinical cases. FSL FAST performs direct segmentation of head CT images, permitting quantitation of gray and white matter densities and volumes, achieving a more complete segmentation than masking methods. "Bias field correction" reduced the covariance of image signal intensities of the total brain and gray matter images (P < 0.01). Correction is larger when the effects of beam hardening and radiation scatter are larger, resulting in improved segmentation. FSL FAST enables direct segmentation of head CT images.

Metastasis of Hepatocellular Carcinoma to the Membrane of Chronic Subdural Hematomas:A Case Report

An 81-year-old man presented with gait disturbance. Two months previously, he suffered from hepatocellular carcinoma and transarterial chemoembolization was performed. A head computed tomography(CT)scan revealed bilateral chronic subdural hematomas. The patient's gait disturbance was improved after achievement of bilateral burr hole drainage. A head CT two months after treatment revealed no recurrence of the hematomas. However, head CT images obtained four months after treatment revealed an abnormal mass in the right parietal region attached to the internal surface of the skull. The mass was located in the same region from where the chronic subdural hematomas were previously removed via burr hole drainage, and was suspected to have originated from the dura mater. We performed craniotomy and total removal of the mass. The dura mater was intact, and macroscopically, the mass originated from the organized membrane of the chronic subdural hematoma. A pathological examination revealed metastasis of hepatocellular carcinoma to the membrane of the chronic subdural hematomas. Head magnetic resonance imaging(MRI)performed 39 days after craniotomy presented a new lesion in the left parietal region attached to the internal surface of the skull. The patient subsequently died 46 days post-operation. When examining chronic subdural hematomas in cancer patients, histological examination of the dura mater, hematoma, and membrane of the hematoma are important. The possibility of metastasis to the capsule of the hematoma should be considered.

Robust head CT image registration pipeline for craniosynostosis skull correction surgery.

Craniosynostosis is a congenital malformation of the infant skull typically treated via corrective surgery. To accurately quantify the extent of deformation and identify the optimal correction strategy, the patient-specific skull model extracted from a pre-surgical computed tomography (CT) image needs to be registered to an atlas of head CT images representative of normal subjects. Here, the authors present a robust multi-stage, multi-resolution registration pipeline to map a patient-specific CT image to the atlas space of normal CT images. The proposed registration pipeline first performs an initial optimisation at very low resolution to yield a good initial alignment that is subsequently refined at high resolution. They demonstrate the robustness of the proposed method by evaluating its performance on 560 head CT images of 320 normal subjects and 240 craniosynostosis patients and show a success rate of 92.8 and 94.2%, respectively. Their method achieved a mean surface-to-surface distance between the patient and template skull of <2.5 mm in the targeted skull region across both the normal subjects and patients.

Head CT for Minor Head Injury Presenting to the Emergency Department in the Era of Choosing Wisely.

IntroductionThe Choosing Wisely campaign currently recommends avoiding computed tomography (CT) of the head in low-risk emergency department (ED) patients with minor head injury, based on validated decision rules. However, the degree of adherence to this guideline in clinical practice is unknown. The objective of this study was to evaluate adherence to the Choosing Wisely campaign’s recommendations regarding head CT imaging of patients with minor head injury in the ED.MethodsWe conducted a retrospective cohort study of adult ED patients at a Level I trauma center. Patients aged ≥ 18 years who presented to the ED with minor head injury were identified via International Classification of Diseases, 9th Revision, Clinical Modification codes. Medical record abstraction was conducted to determine the presence of clinical symptoms of the NEXUS II criteria, medical resource use, and head CT findings. We used descriptive statistics to characterize the study sample, and proportions were used to quantify guidelines adherence.ResultsA total of 489 subjects met inclusion criteria. ED providers appropriately applied the Choosing Wisely criteria for 75.5% of patients, obtaining head CTs when indicated by the NEXUS II rule (41.5%), and not obtaining head CTs when the NEXUS II criteria were not met (34.0%). However, ED providers obtained non-indicated CTs in 23.1% of patients. Less than 2% of the sample did not receive a head CT when imaging was indicated by NEXUS II.ConclusionED providers in our sample had variable adherence to the Choosing Wisely head-CT recommendation, especially for patients who did not meet the NEXUS II criteria.

Implementation of the Canadian CT Head Rule and Its Association With Use of Computed Tomography Among Patients With Head Injury

Approximately 1 in 3 computed tomography (CT) scans performed for head injury may be avoidable. We evaluate the association of implementation of the Canadian CT Head Rule on head CT imaging in community emergency departments (EDs). We conducted an interrupted time-series analysis of encounters from January 2014 to December 2015 in 13 Southern California EDs. Adult health plan members with a trauma diagnosis and Glasgow Coma Scale score at ED triage were included. A multicomponent intervention included clinical leadership endorsement, physician education, and integrated clinical decision support. The primary outcome was the proportion of patients receiving a head CT. The unit of analysis was ED encounter, and we compared CT use pre- and postintervention with generalized estimating equations segmented logistic regression, with physician as a clustering variable. Secondary analysis described the yield of identified head injuries pre- and postintervention. Included were 44,947 encounters (28,751 preintervention and 16,196 postintervention), resulting in 14,633 (32.6%) head CTs (9,758 preintervention and 4,875 postintervention), with an absolute 5.3% (95% confidence interval [CI] 2.5% to 8.1%) reduction in CT use postintervention. Adjusted pre-post comparison showed a trend in decreasing odds of imaging (odds ratio 0.98; 95% CI 0.96 to 0.99). All but one ED reduced CTs postintervention (0.3% to 8.7%, one ED 0.3% increase), but no interaction between the intervention and study site over time existed (P=.34). After the intervention, diagnostic yield of CT-identified intracranial injuries increased by 2.3% (95% CI 1.5% to 3.1%). A multicomponent implementation of the Canadian CT Head Rule was associated with a modest reductionin CT use and an increased diagnostic yield of head CTs for adult trauma encounters in community EDs.

Radiologic evaluation of orbital index among Ghanaians using CT scan

BackgroundOrbital index (OI) expresses the proportion of the orbital height to the orbital width and varies with race, regions within the same race and periods in evolution. This index is useful in forensic medicine, anthropology and surgery. However, the average OI among Ghanaian adults was unknown.AimThe aim of this study was to determine the orbital index of adult Ghanaians and classify them under one of the three predetermined groups.MethodThe study design was a retrospective cross-sectional. A systematic random sampling method was used for selecting 350 adult Ghanaian head computed tomography images available from 1 January to 31 December 2015 at KBTH Hospital. The orbital height and orbital width of each orbit were measured on a 3D CT skull. Data was analysed using Microsoft Excel and Statistical Package for Social Sciences version 20.ResultsThe study had more females than men (167, 47.71%, vs 183, 52.29%). The observed orbital index of Ghanaians in the study was 81.22 ± 4.22. The mean orbital index was 80.52 ± 4.66 in males and 82.15 ± 3.83 in females with their difference being statistically significant (p value <0.05). This placed both genders in the Microseme category of orbit. There was no significant difference between the orbital index of the two orbital sides (left and right orbits).ConclusionThe study found Ghanaians in the category of the Microseme and also indicated a strong sexual dimorphism. The outcome of this study may be useful in forensic medicine for skull classification and also for better surgical approach in neurosurgery as well as cosmetic surgery.

Computed tomography head imaging 24 hours following injury

Head injuries account for up to 1.4 million ED attendances in England and Wales every year.

Ondansetron-related hemorrhagic posterior reversible encephalopathy syndrome (PRES) following gastric bypass.

BackgroundPosterior reversible encephalopathy syndrome (PRES) is a clinical-radiographic syndrome formally recognized in 1996, which describes specific changes noted on neuroimaging thought to be related to impaired cerebral blood flow autoregulation and endothelial dysfunction. We report a case of PRES in the setting of increased ingestion of ondansetron; complicated by hemorrhagic transformation and refractory intracranial hypertension. We hypothesize an association of 5-HT3 antagonism and PRES.FindingsThis is a case study report; with review of previously published literature through PubMed search. We describe the case of a 25 year old man following bariatric surgery who increased his ingestion of ondansetron, taking up to 40 tablets/day due to excessive nausea and vomiting. The patient was hospitalized for progressively more severe headache of 1 week’s duration. Computed tomography (CT) revealed bilateral cerebral edema in the parietal and occipital lobes in the setting of elevated blood pressure (BP). Three days into his admission, following improvement in his BP with oral anti-hypertensive but continued use of the ondansetron, the patient developed near complete blindness. CT head imaging revealed progression of the posterior cerebral edema and intraparenchymal hemorrhage. He was admitted to our ICU and despite supportive treatment, his neurological examination worsened while CT head imaging findings remained stable. Invasive multimodality monitoring revealed elevated intracranial pressure. The patient was aggressively treated and after a prolonged hospitalization and rehabilitation course, made a significant recovery.ConclusionThis case highlights a very rare potential neurological complication of ondansetron, a commonly used medication. We hypothesize an underlying association between PRES and 5-HT3 antagonism, via the latter’s potential role in endothelial dysfunction. Prompt recognition and treatment of PRES is essential, in order to prevent secondary cerebral injury and the associated potentially grave consequences.

CT-LP Is Still the Appropriate Evaluation for Subarachnoid Hemorrhage

Head computed tomography (CT) imaging along with lumbar puncture (LP) has been the conventional evaluation for subarachnoid hemorrhage (SAH).

Validated automatic brain extraction of head CT images

BackgroundX-ray computed tomography (CT) imaging of the brain is commonly used in diagnostic settings. Although CT scans are primarily used in clinical practice, they are increasingly used in research. A fundamental processing step in brain imaging research is brain extraction — the process of separating the brain tissue from all other tissues. Methods for brain extraction have either been 1) validated but not fully automated, or 2) fully automated and informally proposed, but never formally validated. AimTo systematically analyze and validate the performance of FSL's brain extraction tool (BET) on head CT images of patients with intracranial hemorrhage. This was done by comparing the manual gold standard with the results of several versions of automatic brain extraction and by estimating the reliability of automated segmentation of longitudinal scans. The effects of the choice of BET parameters and data smoothing is studied and reported. MethodsAll images were thresholded using a 0–100Hounsfield unit (HU) range. In one variant of the pipeline, data were smoothed using a 3-dimensional Gaussian kernel (σ=1mm3) and re-thresholded to 0–100HU; in the other, data were not smoothed. BET was applied using 1 of 3 fractional intensity (FI) thresholds: 0.01, 0.1, or 0.35 and any holes in the brain mask were filled.For validation against a manual segmentation, 36 images from patients with intracranial hemorrhage were selected from 19 different centers from the MISTIE (Minimally Invasive Surgery plus recombinant-tissue plasminogen activator for Intracerebral Evacuation) stroke trial. Intracranial masks of the brain were manually created by one expert CT reader. The resulting brain tissue masks were quantitatively compared to the manual segmentations using sensitivity, specificity, accuracy, and the Dice Similarity Index (DSI). Brain extraction performance across smoothing and FI thresholds was compared using the Wilcoxon signed-rank test. The intracranial volume (ICV) of each scan was estimated by multiplying the number of voxels in the brain mask by the dimensions of each voxel for that scan. From this, we calculated the ICV ratio comparing manual and automated segmentation: ICVautomatedICVmanual.To estimate the performance in a large number of scans, brain masks were generated from the 6 BET pipelines for 1095 longitudinal scans from 129 patients. Failure rates were estimated from visual inspection. ICV of each scan was estimated and an intraclass correlation (ICC) was estimated using a one-way ANOVA. ResultsSmoothing images improves brain extraction results using BET for all measures except specificity (all p<0.01, uncorrected), irrespective of the FI threshold. Using an FI of 0.01 or 0.1 performed better than 0.35. Thus, all reported results refer only to smoothed data using an FI of 0.01 or 0.1. Using an FI of 0.01 had a higher median sensitivity (0.9901) than an FI of 0.1 (0.9884, median difference: 0.0014, p<0.001), accuracy (0.9971 vs. 0.9971; median difference: 0.0001, p<0.001), and DSI (0.9895 vs. 0.9894; median difference: 0.0004, p<0.001) and lower specificity (0.9981 vs. 0.9982; median difference: −0.0001, p<0.001). These measures are all very high indicating that a range of FI values may produce visually indistinguishable brain extractions. Using smoothed data and an FI of 0.01, the mean (SD) ICV ratio was 1.002 (0.008); the mean being close to 1 indicates the ICV estimates are similar for automated and manual segmentation.In the 1095 longitudinal scans, this pipeline had a low failure rate (5.2%) and the ICC estimate was high (0.929, 95% CI: 0.91, 0.945) for successfully extracted brains. ConclusionBET performs well at brain extraction on thresholded, 1mm3 smoothed CT images with an FI of 0.01 or 0.1. Smoothing before applying BET is an important step not previously discussed in the literature. Analysis code is provided.

Use of Public Data to Target Variation in Providers' Use of CT and MR Imaging among Medicare Beneficiaries.

To examine geographic variation in providers' use of diagnostic imaging to identify potential targets for quality improvement initiatives after adjusting for imaging referral across hospital referral regions (HRRs). Using two Centers for Medicare and Medicaid Services datasets, the authors included all claims for beneficiaries enrolled in the Medicare fee-for-service program. Diagnostic imaging procedures were selected on the basis of common procedure coding system codes, excluding interventional procedures. The authors assessed providers' use of imaging for each HRR after creating an imaging referral index (IRI) to adjust for imaging referral rates across HRRs. Relative risk statistics were used to assess geographic variation. The authors calculated two imaging measures for computed tomography (CT) and magnetic resonance (MR) imaging: IRI-adjusted utilization intensity (number of examinations per 1000 beneficiaries) and total payments (in dollars, after deducting deductibles and coinsurances) in each HRR. High-impact regions were defined as those in the highest deciles for both imaging intensity and payment. For 34 million Medicare beneficiaries, 124 million unique diagnostic imaging services (totaling $5.6 billion) were performed in 2012. The average adjusted CT utilization intensity ranged from 330.4 studies per 1000 beneficiaries in the lowest decile to 684.0 in the highest decile (relative risk, 2.1); adjusted MR imaging utilization intensity varied from 105.7 studies per 1000 beneficiaries to 256.3 (relative risk, 2.4). The most common CT and MR imaging procedures were head CT and lumbar spine MR imaging. With use of public data, the authors identified a wide variation in imaging use across the United States. Potential targets for future imaging quality improvement initiatives include head CT and lumbar spine MR imaging.

Retrospective analysis of head computed tomography imaging in forensic cases that are admitted to emergency room with minor head trauma

Retrospective analysis of head computed tomography imaging in forensic cases that are admitted to emergency room with minor head trauma

Missed strokes using computed tomography imaging in patients with vertigo: population-based cohort study.

The purpose of this study was to determine the proportion of emergency department (ED) patients with a diagnosis of peripheral vertigo who received computed tomography (CT) head imaging in the ED and to examine whether strokes were missed using CT imaging. This population-based retrospective cohort study assessed patients who were discharged from an ED in Ontario, Canada, with a diagnosis of peripheral vertigo, April 2006 to March 2011. Patients who received CT imaging (exposed) were matched by propensity score methods to patients who did not (unexposed). If performed, CT imaging was presumed to be negative for stroke because brain stem/cerebellar stroke would result in hospitalization. We compared the incidence of stroke within 30, 90, and 365 days subsequent to ED discharge between groups, to determine whether the exposed group had a higher frequency of early strokes than the matched unexposed group. Among 41 794 qualifying patients, 8596 (20.6%) received ED head CT imaging, and 99.8% of these patients were able to be matched to a control. Among exposed patients, 25 (0.29%) were hospitalized for stroke within 30 days when compared with 11 (0.13%) among matched nonexposed patients. The relative risk of a 30- and 90-day stroke among exposed versus unexposed patients was 2.27 (95% confidence interval, 1.12-4.62) and 1.94 (95% confidence interval, 1.10-3.43), respectively. There was no difference between groups at 1 year. Strokes occurred at a median of 32.0 days (interquartile range, 4.0-33.0 days) in exposed patients, compared with 105 days (interquartile range, 11.5-204.5) in unexposed patients. One fifth of patients diagnosed with peripheral vertigo in Ontario received imaging that is not recommended in guidelines, and that imaging was associated with missed strokes.

58 Head Trauma and CT Imaging: A Review of Relevant Case Law

Little is known about the liability risks emergency providers face when deciding whether to order head computed tomography (CT) in patients with head trauma. We describe the patient characteristics and legal outcomes of lawsuits levied against providers for their failure to order a CT in cases of head trauma and describe the potential impact of available clinical decision rules (CDRs) on each case.

Orbital size measurement based on computed tomography imaging for surgical safety

Determining the orbital size makes it possible to manoeuvre safely within theorbit during a surgical procedure. Based on the measurements performed ona multi-layer head computed tomography images, the length was determined of the medial, superior, inferior and lateral orbital walls. Also angles were determined between the superior and inferior walls, between the medial and lateral walls, between the inferior wall and Frankfurt plane and between the anterior and posterior segments of the orbital wall. With these measurements it was possible to establish that the safe space for surgical exploration of the orbit (that is the space between the orbital margin and optic canal) is approximately 40 mm. Moreover, it was determined that the medial wall is parallel to the vertical axis of the body and that the angle between the inferior wall and the Frankfurt plane is 19.7°. The angle between the posterior segment of the inferior wall (posterior to the inferior orbital fissure) and the anterior segment is 130.8°. These data will significantly increase the safety of orbital surgeries.

Diagnostic yield of head computed tomography for the hospitalized medical patient with delirium.

Delirium is common in hospitalized patients and warrants early diagnosis and treatment. Often the evaluation of delirium includes head computed tomography imaging. However, in hospitalized medical patients, the yield of head computed tomography is unknown. To determine the diagnostic yield of head computed tomography when evaluating a hospitalized medical patient with delirium in the absence of a recent fall, head trauma, or new neurologic deficit. Retrospective medical record review at a large academic medical center in Boston, Massachusetts. We reviewed all medical records for head computed tomography scans performed from January 2010 through November 2012 in patients on the general medicine or medical subspecialties units. A "positive" head computed tomography was defined as an intracranial process that could explain delirium. An "equivocal" head computed tomography was defined as the presence of a finding of unclear significance in relation to delirium. There were 398 patients hospitalized for >24 hours who underwent head computed tomography for delirium. Two hundred twenty head computed tomography studies met eligibility criteria, with 6 (2.7%) positive and 4 (1.8%) equivocal results. All positive and equivocal findings resulted in change in management. The diagnostic yield of head computed tomography in determining the cause of delirium in hospitalized patients is low. Due to the low rate of positive findings, head imaging is unnecessary in the majority of cases of delirium. However, there may be a subset of high-risk individuals in which head imaging is indicated.

Computed tomography in management of patients with non-localizing headache.

To assess the usefulness of a computed tomography scan in patients with non-localized headache. One-hundred and forty-two patients with non-localized headache were included in a retrospective study after reviewing the medical records of 896 patients at the Radiology Department, Sultan Qaboos University Hospital. Patients with neurological deficits, head injury, previous intracranial intervention, or malignancy were excluded. Radiological findings of all patients were reviewed and results were divided into 3 groups: 1) no intracranial abnormality; 2) with clinically significant intracranial abnormality; and 3) positive without clinical significance or with extracranial abnormality. All patient history records were reviewed for a period of six months following their initial computed tomography scan to assess their clinical outcomes. The cost of computed tomography examination and patient radiation dose were calculated. Of the 142 patients, 64% were females and 36% males (7% pediatric) with an age range of 4-87 years (mean: 36.2 years). Among the patients, 70% demonstrated negative computed tomography findings (grade 1), only 4% showed clinically significant findings (grade 2), and 26% demonstrated incidental positive findings with no clinical significance (grade 3). The average cost of computed tomography head examination was approximately 60 Omani Riyal ($156). The clinically significant positive cases were fewer than expected. The average estimated radiation dose for these patients was calculated and found to be around 5 times the radiation from computed tomography of the sinuses (approximately 1.84 mSv). Computed tomography head imaging in patients with non-localized headache has a low likelihood for any significant intracranial lesion. Therefore, it is essential to develop local standard operating procedures to promote better utilization of this type of imaging service.

Combined multi-kernel head computed tomography images optimized for depicting both brain parenchyma and bone.

The hybrid convolution kernel technique for computed tomography (CT) is known to enable the depiction of an image set using different window settings. Our purpose was to decrease the number of artifacts in the hybrid convolution kernel technique for head CT and to determine whether our improved combined multi-kernel head CT images enabled diagnosis as a substitute for both brain (low-pass kernel-reconstructed) and bone (high-pass kernel-reconstructed) images. Forty-four patients with nondisplaced skull fractures were included. Our improved multi-kernel images were generated so that pixels of >100 Hounsfield unit in both brain and bone images were composed of CT values of bone images and other pixels were composed of CT values of brain images. Three radiologists compared the improved multi-kernel images with bone images. The improved multi-kernel images and brain images were identically displayed on the brain window settings. All three radiologists agreed that the improved multi-kernel images on the bone window settings were sufficient for diagnosing skull fractures in all patients. This improved multi-kernel technique has a simple algorithm and is practical for clinical use. Thus, simplified head CT examinations and fewer images that need to be stored can be expected.

Infection Rates, Fevers, and Associated Factors in Pediatric Severe Traumatic Brain Injury

Abstract Infections can increase medical costs and worsen patient outcomes. Our aims in pediatric severe traumatic brain injury (sTBI) patients were to determine the infection and fever rates, and to report on associated clinical, imaging, treatment, and outcome factors. We included 180 sTBI patients (presedation Glasgow Coma Scale ≤ 8 and Maximum Abbreviated Injury Scale ≥ 4) admitted to our pediatric intensive care unit. Overall, 17% of sTBI patients (n=30 of 180) developed 36 infections, consisting primarily of urinary tract infections (UTIs; n=13 of 36) and ventilator-associated pneumonias (n=11 of 36). Most infections were nosocomial, occurring >2 days after admission. Fever was found in 36% of sTBI patients during the first few hospital days, but fewer than 7% of patients had infections. Infections occurred more frequently in sTBI patients who were older, heavier, and with a higher injury severity score (ISS; p<0.05). Admission head computed tomography imaging abnormalities (subarachnoid hemorrhage, intraventricular hemorrhage, and diffuse axonal injury), placement of an intracranial pressure (ICP) monitor, and administration of ICP-lowering therapies (hypertonic saline, mannitol, and thiopental) were associated with infections (p<0.05). Those with infections had fewer ventilator-free days, greater hospital lengths of stays, and were less likely to be discharged home. Logistic regression demonstrated that infections were independently associated with use of hypertonic saline (odds ratio [OR], 4.46; p=0.001) and higher ISS (OR, 1.05; p=0.028). In summary, infections were prevalent in sTBI patients and were associated with greater head-imaging abnormalities and use of ICP-lowering therapies. Hypertonic saline administration was strongly associated with infection, but further analyses are required to determine the nature of this relationship. Fever was a poor indicator of infection after sTBI.

Parental Knowledge of Potential Cancer Risks From Exposure to Computed Tomography

Computed tomography (CT) imaging of children is increasing in emergent settings without an understanding of parental knowledge of potential cancer risks. In children with head injuries, our primary objective was to determine the proportion of parents who were aware of the potential of CT to increase a child's lifetime risk of malignancy. We also examined willingness to proceed with recommended CT after risk disclosure and preference to be informed of potential risks. This was a prospective cross-sectional survey of parents whose children presented to a tertiary care pediatric emergency department with a head injury. Survey questions were derived and validated by using expert opinion, available literature, and pre- and pilot testing of questions with the target audience. Of the 742 enrolled parents, 454 (61.2%) were female and 594 (80.0%) were aged 31 to 50 years. Importantly, 357 (46.8%) were aware of the potential for an increased lifetime malignancy risk from CT. Before risk estimate provision, the proportion of parents "very willing/willing" to proceed with head CT was 90.4%; after disclosure, willingness decreased to 69.6% (P < .0001), and 42 (5.6%) would refuse the CT. Of note, 673 (90.3%) wished to be informed of potential malignancy risks. Approximately half of the participating parents were aware of the potential increased lifetime malignancy risk associated with head CT imaging. Willingness to proceed with CT testing was reduced after risk disclosure but was a significant barrier for a small minority of parents. Most parents wanted to be informed of potential malignancy risks before proceeding with imaging.