The use of mobile computed tomography in intensive care: regulatory compliance and radiation protection

Limited Evaluation of Image Quality Produced by a Portable Head CT Scanner (CereTom) in a Neurosurgery Centre

INTRODUCTION

Computed tomography (CT) is the preferred diagnostic toolkit for head and brain imaging of head injury. A recent development is the invention of a portable CT scanner that can be beneficial from a clinical point of view.

AIM

To compare the quality of CT brain images produced by a fixed CT scanner and a portable CT scanner (CereTom).

METHODS

This work was a single-centre retrospective study of CT brain images from 112 neurosurgical patients. Hounsfield units (HUs) of the images from CereTom were measured for air, water and bone. Three assessors independently evaluated the images from the fixed CT scanner and CereTom. Streak artefacts, visualisation of lesions and grey-white matter differentiation were evaluated at three different levels (centrum semiovale, basal ganglia and middle cerebellar peduncles). Each evaluation was scored 1 (poor), 2 (average) or 3 (good) and summed up to form an ordinal reading of 3 to 9.

RESULTS

HUs for air, water and bone from CereTom were within the recommended value by the American College of Radiology (ACR). Streak artefact evaluation scores for the fixed CT scanner was 8.54 versus 7.46 (Z = -5.67) for CereTom at the centrum semiovale, 8.38 (SD = 1.12) versus 7.32 (SD = 1.63) at the basal ganglia and 8.21 (SD = 1.30) versus 6.97 (SD = 2.77) at the middle cerebellar peduncles. Grey-white matter differentiation showed scores of 8.27 (SD = 1.04) versus 7.21 (SD = 1.41) at the centrum semiovale, 8.26 (SD = 1.07) versus 7.00 (SD = 1.47) at the basal ganglia and 8.38 (SD = 1.11) versus 6.74 (SD = 1.55) at the middle cerebellar peduncles. Visualisation of lesions showed scores of 8.86 versus 8.21 (Z = -4.24) at the centrum semiovale, 8.93 versus 8.18 (Z = -5.32) at the basal ganglia and 8.79 versus 8.06 (Z = -4.93) at the middle cerebellar peduncles. All results were significant with P-value < 0.01.

CONCLUSIONS

Results of the study showed a significant difference in image quality produced by the fixed CT scanner and CereTom, with the latter being more inferior than the former. However, HUs of the images produced by CereTom do fulfil the recommendation of the ACR.

Pediatric neurocritical care: a neurology consultation model and implication for education and training

Pediatric neurocritical care is developing specialization within pediatric intensive care and pediatric neurology practice, and the evolving clinical expertise has relevance to training and education in both fields. We describe a model of service using a Neurology Consulting Team in the intensive care unit setting. Medical records were reviewed from a 32-month cohort of Neurology Consulting Team referrals. Six hundred eighty-nine (19%) of 3719 patients admitted to the intensive care unit were assessed by the team. The most common diagnostic categories were seizures, neurosurgical, cerebrovascular, or central nervous system infection. Fifty-seven percent (350 of 615 patients) required mechanical ventilation. Cohort mortality was 7% vs 2% for the general intensive care population (P < 0.01). The team provided 4592 initial and subsequent consultations; on average there were five to six new consultations per week. Each patient had a median of two (interquartile range, 1 to 6) consultations during admission. Three quarters of the cohort required neurodiagnostic investigation (1625 tests), with each patient undergoing a median of two (range, 0 to 3) studies. Taken together, the subset of pediatric intensive care unit patients undergoing neurology consultation, investigation, and management represents a significant practice experience for trainees, which has implications for future curriculum development in both pediatric critical care medicine and pediatric neurology.

Head computed tomography scanning during pediatric neurocritical care: diagnostic yield and the utility of portable studies

BACKGROUND

We report our use of portable head computed tomography (CT) and the diagnostic yield and radiation dose from head CT in the pediatric intensive care unit (PICU).

METHODS

204 PICU patients underwent head CT during 2008-2009. Therapeutic interventions and resource intensity during CT were categorized. Severity of illness was summarized using the pediatric risk of mortality (PRISM-III) model. Estimates of patient radiation dose were based on dose measurements made in four anthropomorphic head phantoms.

RESULTS

242 (62%) out of 391 head CT studies were portable. New pathology was identified on 80 (40%) scans. CT findings prompted a change in management in 46 (23%) patients; 25 of these resulted in life-extending treatments and 21 had forgoing of life-sustaining treatments within 24 hours. 26 patients with PRISM score greater than 30% underwent CT; 23 (88%) of these were portable. More portable versus fixed examinations were performed in patients requiring extracorporeal membrane oxygenation, inhaled nitric oxide, high levels of positive end expiratory pressure, and those with high vasopressor scores (P < 0.05). Estimated patient dose from portable CT was 83 ± 6 mGy compared to 72 ± 5 mGy for patients imaged on a fixed scanner (P < 0.0001).

CONCLUSION

Two-thirds of CT scans obtained in the PICU were portable because of patients' intensity of therapy and illness severity. Portable CT showed major new pathology in greater than 1/3 and led to a change in management in 1/4 of higher acuity patients scanned. The estimated radiation dose from portable CT is within the current national guidelines.