Comparative anatomy of dissected optic lobes, optic ventricles, midbrain tectum, collicular ventricles, and aqueduct: evolutionary modifications as potential explanation for non-tumoral aqueductal anomalies in humans.

PURPOSE: An extensive literature has postulated multiple etiologies for aqueductal stenosis. No publications were found, discussing that evolutionary modifications might explain aqueductal anomalies. This study's objectives were to review the evolutionary modifications of vertebrates' tectum structures that might explain human aqueduct anomalies. Undertaking vertebrate comparative study is currently not feasible in view of limitations in obtaining vertebrate material. Thus, vertebrate material collected, injected, dissected, and radiographed in the early 1970s was analyzed, focusing on the aqueduct and components of the midbrain tectum. METHODS: Photographs of brain dissections and radiographs of the cerebral ventricles and arteries of adult shark, frog, iguana, rabbit, cat, dog, and primate specimens, containing a barium-gelatin radiopaque compound, were analyzed focusing on the aqueduct, the optic ventricles, the quadrigeminal plate, and collicular ventricles. The anatomic information provided by the dissections and radiographs is not reproducible by any other radiopaque contrast currently available. RESULTS: Dissected and radiographed cerebral ventricular and arterial systems of the vertebrates demonstrated midbrain tectum changes, including relative size modifications of the mammalian components of the tectum, simultaneously with the enlargement of the occipital lobe. There is a transformation of pre-mammalian optic ventricles to what appear to be collicular ventricles in mammals, as the aqueduct and collicular ventricle form a continuous cavity. CONCLUSIONS: The mammalian tectum undergoes an evolutionary cephalization process consisting of relative size changes of the midbrain tectum structures. This is associated with enlargement of the occipital lobe, as part of overall neocortical expansion. Potentially, aqueductal anomalies could be explained by evolutionary modifications.

Utility of MRI for cervical spine clearance after blunt traumatic injury: a meta-analysis.

OBJECTIVES: To quantify the rate of unstable injuries detected by MRI missed on CT in blunt cervical spine (CS) trauma patients and assess the utility of MRI in CS clearance. METHODS: We undertook a systematic review of worldwide evidence across five major medical databases and performed a meta-analysis. Studies were included if they reported the number of unstable injuries or gave enough details for inference. Variables assessed included severity, CT/MRI specifications, imaging timing, and outcome/follow-up. Pooled incidences of unstable injury on follow-up weighted by inverse-of-variance among all included and obtunded or alert patients were reported. RESULTS: Of 428 unique citations, 23 proved eligible, with 5,286 patients found, and 16 unstable injuries reported in five studies. The overall pooled incidence is 0.0029 %. Among studies reporting only obtunded patients, the pooled incidence is 0.017 %. In alert patients, the incidence is 0.011 %. All reported positive findings were critically reviewed, and only 11 could be considered truly unstable. CONCLUSIONS: There is significant heterogeneity in the literature regarding the use of imaging after a negative CT. The finding rate on MRI for unstable injury is extremely low in obtunded and alert patients. Although MRI is frequently performed, its utility and cost-effectiveness needs further study. KEY POINTS: • There were 16 unstable injuries on follow-up MRI among 5286 patients. • The positive finding rate among obtunded patients was 0.12 %. • The positive finding rate among alert, awake patients was 0.72 %. • MRI has a high false-positive rate; its utility mandates further studies. • The use and role of "confirmatory" tests shows wide variations.

Cost-Effectiveness of Tomosynthesis in Annual Screening Mammography.

OBJECTIVE: The purpose of this study was to evaluate the cost-effectiveness of the addition of annual screening tomosynthesis to 2D digital mammography alone for women beginning at 40 years old and to determine differences for age decade subgroups. MATERIALS AND METHODS: Decision-tree analysis comparing annual tomosynthesis versus 2D mammography alone from a federal payer perspective and lifetime horizon was created from published multiinstitutional data, published institutional data, literature values, and Medicare reimbursement rates. Cost-effectiveness was calculated through incremental cost-effectiveness ratios and net monetary benefit calculations. Sensitivity analyses were performed to determine the implication of different variables including changes in recall rate and disutility for false-positives. RESULTS: Base-case analysis showed an incremental cost per quality-adjusted life year gained for tomosynthesis over 2D alone for all ages (≥ 40 years old) of $20,230, 40- to 49-year-old subgroup of $20,976, 50- to 59-year-old subgroup of $49,725, 60- to 69-year-old subgroup of $44,641, and ≥ 70-year-old subgroup of $82,500. Net monetary benefit per decade in the 40- to 49-year-old subgroup was $1,598, 50- to 59-year-old subgroup of $546, 60- to 69-year-old subgroup of $535, and ≥ 70-year-old subgroup of $501. Tomosynthesis was the better strategy in 63.2% of the iterations according to probabilistic sensitivity analysis. CONCLUSION: Addition of annual screening tomosynthesis to 2D mammography beginning at the age of 40 years was cost-effective compared with 2D mammography alone in our analysis. Three times greater net monetary benefits were found in women 40-49 years old compared with those 50-59 years old.

Cerebral function monitoring on a general paediatric ward: feasibility and potential.

UNLABELLED: Cerebral function monitoring is widely used in neonatal intensive care, but its potential role in assessment of older infants is scarcely reported. We reviewed the use of cerebral function monitoring on a general paediatric ward in a series of young infants admitted with abnormal movements. Review of the amplitude-integrated EEG obtained by cerebral function monitoring revealed electrographic seizures in four of seven infants monitored. We also surveyed general paediatric wards in hospitals in our region of the UK to ask about current use of cerebral function monitoring and local availability of formal electroencephalography services. Cerebral function monitoring was not being used in the 16 other paediatric departments surveyed, and there was very limited provision for obtaining a full-array electroencephalogram out-of-hours. CONCLUSION: With adequate training and education, it is feasible to undertake cerebral function monitoring on a general paediatric ward. Continuous cerebral function monitoring is a tool that has potential use for detecting clinical seizures and augmenting clinical neuro-observations of young children admitted to a general paediatric ward. WHAT IS KNOWN: • In intensive care settings, cerebral function monitoring (CFM) has long been used for the continuous bedside monitoring of brain function in critically ill neonates, children and adults. • Very few studies have looked at the use of CFM outside of the intensive care setting, and it is presently unclear if CFM is used in the general paediatric ward. What is new: • CFM is presently not widely used in the general paediatric setting. • With appropriate training and support, CFM can be successfully introduced to the general paediatric ward with the potential to enhance the clinical monitoring of young infants admitted with abnormal movements.

Utility analysis of management strategies for suspected subarachnoid haemorrhage in patients with thunderclap headache with negative CT result.

PURPOSE: To determine the most effective follow-up strategy for evaluation of patients with thunderclap headache and negative initial non-contrast CT for acute subarachnoid haemorrhage (SAH). MATERIALS AND METHODS: Institutional review was performed to assess the frequency of CT angiography (CTA) in screening patients with negative non-contrast CT. A comparative effectiveness analysis based on decision tree modelling was subsequently performed to assess three different strategies--no follow-up, lumbar puncture (LP) and CTA. The clinical probabilities and utilities from literature were used to design the decision tree. Base-case scenario utility calculations, sensitivity analyses and probabilistic Monte Carlo simulation were performed. RESULTS: Institutional review of recent data in the last two years demonstrates frequent use of CTA in patients with thunderclap headache with limited utility. The decision tree analysis shows CT with LP follow-up to be the most effective strategy with the highest expected utility of 0.79926 quality-adjusted life-year (QALY) compared with 0.79875 QALY for no follow-up and 0.79869 QALY for CTA follow-up. Monte Carlo simulation showed LP was the best strategy in 86.4% of all iterations. Sensitivity analyses demonstrate that CT without follow-up is the best strategy only when the sensitivity of CT is very high (99.6%) or the pre-test probability of SAH in a patients with thunderclap headache with negative initial CT is low (1.6%). CONCLUSIONS: CT with no follow-up was shown to be the best strategy when the pre-test probability of SAH is low (<1.6%) or the sensitivity of initial non-contrast CT for blood is high (>99.6%). Otherwise, LP should be the preferred strategy for follow-up.

Radiographic and Pathologic Manifestations of Uncommon and Rare Pulmonary Lesions.

Pulmonary opacities/nodules are common findings on computed tomography examinations, which may represent an underlying infections or malignancy. However, not every pulmonary nodule or opacity represents malignancy or infection. We present a pictorial essay illustrating common as well as obscure noninfectious, nonmalignant pulmonary lesions. Lesions discussed include organizing pneumonia, Langerhans cell histiocytosis, pulmonary amyloidosis, hyalinizing granuloma, tumourlet (benign localized neuroendocrine cell proliferations), atypical alveolar hyperplasia, inflammatory myofibroblastic tumour, papillary alveolar adenoma, plasma cell granuloma, juvenile xanthogranuloma, and sclerosing hemangiomas. We discuss the clinical presentation, prevalence, radiographic clues, pathology, and diagnostic pitfalls of these rare lesions.

Use of follow-up imaging in isolated perimesencephalic subarachnoid hemorrhage: a meta-analysis.

BACKGROUND AND PURPOSE: Multiple studies have shown that negative computed tomographic angiograms (CTAs) are reliable in excluding aneurysms in patients with isolated perimesencephalic subarachnoid hemorrhage (pSAH). We evaluate the use of digital subtraction angiography versus CTA for initial diagnosis and of angiographic follow-ups in patients with pSAH by performing an institutional analysis and a meta-analysis of literature. METHODS: Retrospective institutional analysis of patients with pSAH was performed from 2008 to 2014. The number and types of follow-up imaging studies were tabulated. Initial and follow-up studies were evaluated by an experienced neuroradiologist for intracranial aneurysm. Meta-analysis of literature was performed to assess the use of initial digital subtraction angiography and of follow-up imaging. RESULTS: Our institutional review revealed no additional use of initial digital subtraction angiography or of any angiographic follow-up after initial negative CTA in patients with pSAH on noncontrast CT. Meta-analysis of 40 studies yielded a total of 1031 patients. Only 8 aneurysms were first diagnosed on follow-ups (0.78%). Careful review showed that some of these aneurysms reported on follow-up are of questionable validity. Initial digital subtraction angiography and follow-up imaging after a negative initial CTA showed no statistically significant benefits. CONCLUSIONS: In patients meeting the strict imaging criteria of pSAH, initial negative CTA is reliable in excluding aneurysms. A critical review of the literature through meta-analysis shows no foundation for multiple follow-up studies in patients with pSAH.

Organ laceration grading adherence by radiologists.

American Association for the Surgery of Trauma (AAST) abdominopelvic organ laceration grading is used to determine which patients can be managed non-operatively. We assess a change in the use of AAST grading system by radiologists at a single, large, academic institution before and after a one-time departmental intervention and reviewed non-graded reports evaluating if grading could be inferred. After IRB approval, a keyword search for "laceration" identified traumatic abdominopelvic CT reports in a 2-year period before and after the one-time intervention. Reports were reviewed to determine if an organ laceration was seen, if it was graded by AAST criteria, and if grading could be inferred for non-graded reports. T test was performed to assess statistical significance. Before the intervention, 348 reports contained the keyword "laceration," 81 with lacerations, 31 graded (38 %). After the intervention, 302 reports were found, 79 with lacerations, 59 graded (75 %). The increase was statistically significant (p < 0.0001). A decreasing trend in grading was seen over time following the intervention. Two out of 50 (4 %) pre-intervention and four out of 20 (20 %) post-intervention reports gave enough detailed descriptions for the grading to be inferred when it was not explicitly stated. Non-graded reports did not describe laceration parenchymal depth and subcapsular hematoma surface area percentage; however, the presence/absence of active extravasation, omitted in the 20-year-old AAST grading scheme, was described in every report. One-time departmental intervention yielded a significant increase in adherence to AAST laceration grading. Lack of perfect compliance, which diminished over time, suggests a need for further reinforcement.

Cost-effectiveness of angiographic imaging in isolated perimesencephalic subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: The purpose of this study is to perform a comprehensive cost-effectiveness analysis of all possible permutations of computed tomographic angiography (CTA) and digital subtraction angiography imaging strategies for both initial diagnosis and follow-up imaging in patients with perimesencephalic subarachnoid hemorrhage on noncontrast CT. METHODS: Each possible imaging strategy was evaluated in a decision tree created with TreeAge Pro Suite 2014, with parameters derived from a meta-analysis of 40 studies and literature values. Base case and sensitivity analyses were performed to assess the cost-effectiveness of each strategy. A Monte Carlo simulation was conducted with distributional variables to evaluate the robustness of the optimal strategy. RESULTS: The base case scenario showed performing initial CTA with no follow-up angiographic studies in patients with perimesencephalic subarachnoid hemorrhage to be the most cost-effective strategy ($5422/quality adjusted life year). Using a willingness-to-pay threshold of $50 000/quality adjusted life year, the most cost-effective strategy based on net monetary benefit is CTA with no follow-up when the sensitivity of initial CTA is >97.9%, and CTA with CTA follow-up otherwise. The Monte Carlo simulation reported CTA with no follow-up to be the optimal strategy at willingness-to-pay of $50 000 in 99.99% of the iterations. Digital subtraction angiography, whether at initial diagnosis or as part of follow-up imaging, is never the optimal strategy in our model. CONCLUSIONS: CTA without follow-up imaging is the optimal strategy for evaluation of patients with perimesencephalic subarachnoid hemorrhage when modern CT scanners and a strict definition of perimesencephalic subarachnoid hemorrhage are used. Digital subtraction angiography and follow-up imaging are not optimal as they carry complications and associated costs.

Comparison of tomosynthesis plus digital mammography and digital mammography alone for breast cancer screening.

PURPOSE: To compare screening recall rates and cancer detection rates of tomosynthesis plus conventional digital mammography to those of conventional digital mammography alone. MATERIALS AND METHODS: All patients presenting for screening mammography between October 1, 2011, and September 30, 2012, at four clinical sites were reviewed in this HIPAA-compliant retrospective study, for which the institutional review board granted approval and waived the requirement for informed consent. Patients at sites with digital tomosynthesis were offered screening with digital mammography plus tomosynthesis. Patients at sites without tomosynthesis underwent conventional digital mammography. Recall rates were calculated and stratified according to breast density and patient age. Cancer detection rates were calculated and stratified according to the presence of a risk factor for breast cancer. The Fisher exact test was used to compare the two groups. Multivariate logistic regression was used to assess the effect of screening method, breast density, patient age, and cancer risk on the odds of recall from screening. RESULTS: A total of 13 158 patients presented for screening mammography; 6100 received tomosynthesis. The overall recall rate was 8.4% for patients in the tomosynthesis group and 12.0% for those in the conventional mammography group (P < .01). The addition of tomosynthesis reduced recall rates for all breast density and patient age groups, with significant differences (P < .05) found for scattered fibroglandular, heterogeneously dense, and extremely dense breasts and for patients younger than 40 years, those aged 40-49 years, those aged 50-59 years, and those aged 60-69 years. These findings persisted when multivariate logistic regression was used to control for differences in age, breast density, and elevated risk of breast cancer. The cancer detection rate was 5.7 per 1000 in patients receiving tomosynthesis versus 5.2 per 1000 in patients receiving conventional mammography alone (P = .70). CONCLUSION: Patients undergoing tomosynthesis plus digital mammography had significantly lower screening recall rates. The greatest reductions were for those younger than 50 years and those with dense breasts. A nonsignificant 9.5% increase in cancer detection was observed in the tomosynthesis group.

Loeys-Dietz syndrome: cardiovascular, neuroradiological and musculoskeletal imaging findings.

Loeys-Dietz syndrome (LDS) is an increasingly recognized autosomal-dominant connective tissue disorder with distinctive radiological manifestations, including arterial tortuosity/aneurysms, craniofacial malformations and skeletal abnormalities. LDS exhibits a more aggressive course than similar disorders, such as Marfan or the vascular subtype of Ehlers-Danlos syndrome, with morbidity and mortality typically resulting from complications of aortic/arterial dissections. Early diagnosis, short-interval follow-up imaging and prophylactic surgical intervention are essential in preventing catastrophic cardiovascular complications. This review focuses on the cardiovascular, neuroradiological and musculoskeletal imaging findings in this disorder and recommendations for follow-up imaging.

Neuroimaging of Meckel's cave in normal and disease conditions.

Meckel's cave is a dural recess in the posteromedial portion of the middle cranial fossa that acts as a conduit for the trigeminal nerve between the prepontine cistern and the cavernous sinus, and houses the Gasserian ganglion and proximal rootlets of the trigeminal nerve. It serves as a major pathway in perineural spread of pathologies such as head and neck neoplasms, automatically upstaging tumours, and is a key structure to assess in cases of trigeminal neuralgia. The purpose of this pictorial review is threefold: (1) to review the normal anatomy of Meckel's cave; (2) to describe imaging findings that identify disease involving Meckel's cave; (3) to present case examples of trigeminal and non-trigeminal processes affecting Meckel's cave. TEACHING POINTS: • Meckel's cave contains the trigeminal nerve between prepontine cistern and cavernous sinus. • Assessment is essential for perineural spread of disease and trigeminal neuralgia. • Key imaging: neural enhancement, enlargement, perineural fat/CSF effacement, skull base foraminal changes.

Cost-effectiveness of Magnetic Resonance Imaging in Cervical Clearance of Obtunded Blunt Trauma After a Normal Computed Tomographic Finding.

Importance: Magnetic resonance imaging (MRI) continues to be performed for cervical clearance of obtunded blunt trauma, despite poor evidence regarding its utility after a normal computed tomographic (CT) finding. Objective: To evaluate the utility and cost-effectiveness of MRI vs no follow-up after a normal cervical CT finding in patients with obtunded blunt trauma. Design, Setting and Participants: This cost-effectiveness analysis evaluated an average patient aged 40 years with blunt trauma from an institutional practice. The analysis used a Markov decision model over a lifetime horizon from a societal perspective with variables from systematic reviews and meta-analyses and reimbursement rates from the Centers for Medicare & Medicaid Services, National Spinal Cord Injury Database, and other large published studies. Data were collected from the most recent literature available. Interventions: No follow-up vs MRI follow-up after a normal cervical CT finding. Results: In the base case of a 40-year-old patient, the cost of MRI follow-up was $14 185 with a health benefit of 24.02 quality-adjusted life-years (QALY); the cost of no follow-up was $1059 with a health benefit of 24.11 QALY, and thus no follow-up was the dominant strategy. Probabilistic sensitivity analysis showed no follow-up to be the better strategy in all 10 000 iterations. No follow-up was the better strategy when the negative predictive value of the initial CT was relatively high (>98%) or the risk of an injury treated with a cervical collar turning into a permanent neurologic deficit was higher than 25% or when the risk of a missed injury turning into a neurologic deficit was less than 58%. The sensitivity and specificity of MRI were varied simultaneously in a 2-way sensitivity analysis, and no follow-up remained the optimal strategy. Conclusions and Relevance: Magnetic resonance imaging had a lower health benefit and a higher cost compared with no follow-up after a normal CT finding in patients with obtunded blunt trauma to the cervical spine, a finding that does not support the use of MRI in this group of patients. The conclusion is robust in sensitivity analyses varying key variables in the model. More literature on these key variables is needed before MRI can be considered to be beneficial in the evaluation of obtunded blunt trauma.

Ectopic intracranial germinoma.

Intracranial ectopic germinomas are often associated with synchronous midline disease. Germinomas involving the corpus callosum are exceedingly rare. The reported imaging appearance is not as varied as one might expect and a review of the literature reveals a few common imaging features amongst most ectopic lesions, including cyst formation. We report a 24-year-old man with panhypopituitarism. Neuroimaging revealed three enhancing lesions involving the pituitary infundibulum, the pineal region, and a parenchymal lesion involving the genu of the corpus callosum. The described ectopic mass, a parenchymal lesion, was associated with small peripheral cysts. Stereotactic biopsy and histopathological evaluation revealed this mass to be a germinoma. Following chemotherapy and radiation therapy, there was near-total resolution of the intracranial disease. Preoperative imaging plays an important role, not only in delineating the extent of disease, but also in assisting in generating an appropriate differential diagnosis. Germinomas in the corpus callosum are exceedingly rare but should be considered in the differential of any young patient with a characteristic cystic and solid intra-axial mass.

Cost-effectiveness Analysis of Follow-up Strategies for Thunderclap Headache Patients With Negative Noncontrast CT.

OBJECTIVES: Accurate diagnosis of acute subarachnoid hemorrhage (SAH) is critical in thunderclap headache patients due to high morbidity and mortality associated with missed aneurysmal bleeds. The objective of this study was to determine the utility of computed tomography angiography (CTA) in managing patients with acute, severe headaches and negative noncontrast CT and assess the cost-effectiveness of three different screening strategies-no follow up, CTA, and lumbar puncture (LP). METHODS: A modeling-based economic evaluation was performed with a time horizon of 1 year for thunderclap headache patients in the emergency department with negative noncontrast CT for SAH. Sensitivity analyses were performed to determine the effect of sensitivity of CT and the prevalence of SAH on cost-effectiveness. RESULTS: Lumbar puncture follow-up has the lowest cost and the highest utility in the mathematical model. The Monte Carlo simulation shows noncontrast CT with LP follow-up to be the most cost-effective strategy in 85.3% of all cases even at a $1 million/quality-adjusted life-years willingness-to-pay. Sensitivity analyses demonstrate that LP follow-up should be performed, except for when CT sensitivity exceeds 99.2% and the SAH prevalence is below 3.2%, where no follow-up may be considered. CONCLUSIONS: Although CTA is frequently used for evaluation of thunderclap headache patients, its utility is not clearly defined. LP follow-up is shown to be the most cost-effective strategy for evaluation of thunderclap headache patients in most clinical settings.

Cost-effectiveness analysis of CTA and LP for evaluation of suspected SAH after negative non-contrast CT.

OBJECTIVES: Diagnostic workup of patients presenting with thunderclap headache and negative initial head CT remains a challenge, with most commonly employed strategies being lumbar puncture (LP) and CT angiography (CTA). The objective of this study was to determine the cost-effectiveness of these options. PATIENTS AND METHODS: A decision model was designed using clinical probabilities, costs, and utilities from published values in the literature. Base case analysis and Monte Carlo simulation were performed using the model to determine the cost-effectiveness of both options. RESULTS: CTA was associated with an expected cost of $747 and an expected utility of 0.798603029. In comparison, LP was associated with a cost of $504 and an expected utility of 0.799259526, making it the optimal strategy from both the cost and the utility perspectives. LP was also the more cost-effective strategy in all iterations in the Monte Carlo simulation. A sensitivity analysis showed that with the 2014 US Medicare reimbursement values, LP would remain the more cost-effective strategy unless its cost exceeded 4 times its current value. CONCLUSION: LP should remain the preferred strategy for evaluation of SAH in patients presenting with thunderclap headache and negative non-contrast head CT. CTA is not an effective replacement, from either a utility or cost perspective.

Thoracic Presentations of Small Round Blue Cell Tumors.

The term "small round blue cell" is frequently used as a cursory radiologic pathological correlation of aggressive tumors throughout the body. We present a pictorial essay of common and uncommon subtypes of small round blue cell tumors in the chest illustrating the characteristic radiologic findings of each lesion. In addition, we review the pathologic findings of each tumor subtype with characteristic hematoxylin- and eosin-stained photomicrographs and immunohistochemical and molecular studies. Represented tumors include small cell carcinoma, Ewing sarcoma, extranodal marginal zone B-cell lymphoma, embryonal rhabdomyosarcoma, desmoplastic small round cell tumor, and posttransplant lymphoproliferative disorder. Understanding and ability to recognize these lesions are essential to broaden the radiologist's differential diagnosis and help guide patient care.