CT scan exposure in children with ventriculo-peritoneal shunts: single centre experience and review of the literature

Reducing radiation exposure and costs: CT body scout views with an enhanced protocol versus conventional radiography after shunt surgery

OBJECTIVE

Ventriculoperitoneal shunt implantation has become standard treatment for cerebrospinal fluid diversion, besides endoscopic third ventriculostomy for certain indications. Postoperative X-ray radiography series of skull, chest and abdomen combined with cranial CT are obtained routinely in many institutions to document the shunt position and valve settings in adult patients. Measures to reduce postoperative radiation exposure are needed, however, there is only limited experience with such efforts. Here, we aim to compare routine postoperative cranial CT plus conventional radiography series (retrospective arm) with cranial CT and body scout views only (prospective arm) concerning both diagnostic quality and radiation exposure.

PATIENTS AND METHODS

After introduction of an enhanced CT imaging protocol, routine skull and abdomen radiography was no longer obtained after VP shunt surgery. The image studies of 25 patients with routine postoperative cranial CT and conventional radiography (retrospective arm of study) were then compared to 25 patients with postoperative cranial CT and CT body scout views (prospective arm of study). Patient demographics such as age, sex and primary diagnosis were collected. The image quality of conventional radiographic images and computed tomography scout views images were independently analyzed by one neurosurgeon and one neuroradiologist.

RESULTS

There were no differences in quality assessments according to three different factors determined by two independent investigators for both groups. There was a statistically significant difference, however, between the conventional radiography series group and the CT body scout view imaging group with regard to radiation exposure. The effective dose estimation calculation yielded a difference of 0.05 mSv (two-tailed t-test, p = 0.044) in favor of CT body scout view imaging. Furthermore, the new enhanced protocol resulted in a reduction of cost and the use of human resources.

CONCLUSION

CT body scout view imaging provides sufficient imaging quality to determine shunt positioning and valve settings. With regard to radiation exposure and costs, we suggest that conventional postoperative shunt series may be abandoned.

Three-Dimensional Visualization of Shunt Valves with Photon Counting CT and Comparison to Traditional X-ray in a Simple Phantom Model

This study introduces an application of innovative medical technology, Photon Counting Computer Tomography (PC CT) with novel detectors, for the assessment of shunt valves. PC CT technology offers enhanced visualization capabilities, especially for small structures, and opens up new possibilities for detailed three-dimensional imaging. Shunt valves are implanted under the skin and redirect excess cerebrospinal fluid, for example, to the abdominal cavity through a catheter. They play a vital role in regulating cerebrospinal fluid drainage in various pathologies, which can lead to hydrocephalus. Accurate imaging of shunt valves is essential to assess the rate of drainage, as their precise adjustment is a requirement for optimal patient care. This study focused on two adjustable shunt valves, the proGAV 2.0® and M. blue® (manufactured by Miethke, Potsdam, Germany). A comprehensive comparative analysis of PC CT and traditional X-ray techniques was conducted to explore this cutting-edge technology and it demonstrated that routine PC CT can efficiently assess shunt valves' adjustments. This technology shows promise in enhancing the accurate management of shunt valves used in settings where head scans are already frequently required, such as in the treatment of hydrocephalus.

The Utilization of Computed Tomography in the Pediatric Emergency Department for Patients With Ventriculoperitoneal Shunts

Introduction Despite all the advantages of computed tomography (CT) scanning, there is a significant concern due to the rising use of CT scans in children with ventriculoperitoneal (VP) shunts. High doses of radiation are absorbed by patients, raising their chance of acquiring cancer. Evaluating a potential VP shunt malfunction is a frequent encounter in the pediatric emergency room, often necessitating the utilization of a CT scan. This study aims to recognize and quantify the utilization of CT scans in an emergency setting for pediatric patients with a clinical suspicion of VP shunt malfunction. Methods This retrospective chart review was conducted on patients who visited the emergency department with suspected VP shunt malfunction in a pediatric tertiary care hospital (King Abdullah Specialist Children Hospital), Riyadh, Saudi Arabia. The study included the files of children between the years 2018 and 2019. Results A total of 119 children were included; the main indication for VP shunt insertion was congenital hydrocephalus at 46.8% (n=52). The median number of CT scans done per patient was seven (IQR=3-9). CT findings were abnormal among 55.6% (n=60). The univariate analysis examining the impact of different factors on CT findings showed an association between an abnormal CT finding and female gender (P=0.017), younger age (P=0.03), and the presence of a cerebral cyst (P=0.001); however, subsequent multivariate analysis was not significant for any of these factors. Twenty-two point three percent (n=25) of the patients required neurosurgical intervention, and the associated factors with neurosurgical intervention included changes in activity level (P=0.04), weakness (P=0.004), and altered mental status (P=0.001). Conclusion Children with VP shunts are susceptible to significant radiation exposure through the utilization of CT scans whenever they present to the ER with suspected shunt malfunction during their lifespan, which puts them at risk of radiation-related complications, such as cancers. CT imaging remains a helpful tool aiding physicians in making accurate decisions. However, in this study, almost half of the children had unremarkable CT findings. Thus, it is imperative to rationalize its use by establishing tailored guidelines that delineate the appropriate circumstances warranting its application.

Computed tomography scan radiation and brain cancer incidence

BACKGROUND

Computed tomography (CT) scans make substantial contributions to low-dose ionizing radiation exposures, raising concerns about excess cancers caused by diagnostic radiation.

METHODS

Deidentified medicare records for all Australians aged 0-19 years between 1985-2005 were linked to national death and cancer registrations to 2012. The National Cancer Institute CT program was used to estimate radiation doses to the brain from CT exposures in 1985-2005, Poisson regression was used to model the dependence of brain cancer incidence on brain radiation dose, which lagged by 2 years to minimize reverse causation bias.

RESULTS

Of 10 524 842 young Australians, 611 544 were CT-exposed before the age of 20 years, with a mean cumulative brain dose of 44 milligrays (mGy) at an average follow-up of 13.5 years after the 2-year lag period. 4472 were diagnosed with brain cancer, of whom only 237 had been CT-exposed. Brain cancer incidence increased with radiation dose to the brain, with an excess relative risk of 0.8 (95% CI 0.57-1.06) per 100 mGy. Approximately 6391 (95% CI 5255, 8155) persons would need to be exposed to cause 1 extra brain cancer.

CONCLUSIONS

For brain tumors that follow CT exposures in childhood by more than 2 years, we estimate that 40% (95% CI 29%-50%) are attributable to CT Radiation and not due to reverse causation. However, because of relatively low rates of CT exposure in Australia, only 3.7% (95% CI 2.3%-5.4%) of all brain cancers are attributable to CT scans. The population-attributable fraction will be greater in countries with higher rates of pediatric scanning.

Establishing proof of concept for sonolucent cranioplasty and point of care ultrasound imaging after posterior fossa decompression for Chiari malformation

BACKGROUND

Evaluation after posterior fossa decompression for Chiari malformation can require repeated imaging, particularly with persistent symptoms. Typically, CT or MRI is used. However, CT carries radiation risk and MRI is costly. Ultrasound is an inexpensive, radiation-free, point-of-care modality that has, thus far, been limited by intact skull and traditional cranioplasty materials. Ultrasound also allows for imaging in different head positions and body postures, which may lend insight into cause for persistent symptoms despite adequate decompression on traditional neutral static CT or MRI. We evaluate safety and feasibility of ultrasound as a post-operative imaging modality in patients reconstructed with sonolucent cranioplasty during posterior fossa decompression for Chiari malformation.

METHODS

Outcomes were analyzed for 26 consecutive patients treated with a Chiari-specific sonolucent cranioplasty. This included infection, need for revision, CSF leak, and pseudomeningocele. Ultrasound was performed point-of-care in the outpatient clinic by the neurosurgery team to assess feasibility.

RESULTS

In eight months mean follow up, there were no surgical site infections or revisions with this novel sonolucent cranioplasty. Posterior fossa anatomy was discernable via transcutaneous ultrasound obtained point-of-care in the clinic setting at follow up visits.

CONCLUSION

We demonstrate proof of concept for ultrasound as a post-operative imaging modality after posterior fossa decompression for Chiari malformation. With further investigation, ultrasound may prove to serve as an alternative to CT and MRI in this patient population, or as an adjunct to provide positional and dynamic information. Use of sonolucent cranioplasty is safe. This technique deserves further study.

First Experience With Postoperative Transcranial Ultrasound Through Sonolucent Burr Hole Covers in Adult Hydrocephalus Patients

BACKGROUND

Managing patients with hydrocephalus and cerebrospinal fluid (CSF) disorders requires repeated head imaging. In adults, it is typically computed tomography (CT) or less commonly magnetic resonance imaging (MRI). However, CT poses cumulative radiation risks and MRI is costly. Ultrasound is a radiation-free, relatively inexpensive, and optionally point-of-care alternative, but is prohibited by very limited windows through an intact skull.

OBJECTIVE

To describe our initial experience with transcutaneous transcranial ultrasound through sonolucent burr hole covers in postoperative hydrocephalus and CSF disorder patients.

METHODS

Using cohort study design, infection and revision rates were compared between patients who underwent sonolucent burr hole cover placement during new ventriculoperitoneal shunt placement and endoscopic third ventriculostomy over the 1-year study time period and controls from the period 1 year before. Postoperatively, trans-burr hole ultrasound was performed in the clinic, at bedside inpatient, and in the radiology suite to assess ventricular anatomy.

RESULTS

Thirty-seven patients with sonolucent burr hole cover were compared with 57 historical control patients. There was no statistically significant difference in infection rates between the sonolucent burr hole cover group (1/37, 2.7%) and the control group (0/57, P = .394). Revision rates were 13.5% vs 15.8% (P = 1.000), but no revisions were related to the burr hole or cranial hardware.

CONCLUSION

Trans-burr hole ultrasound is feasible for gross evaluation of ventricular caliber postoperatively in patients with sonolucent burr hole covers. There was no increase in infection rate or revision rate. This imaging technique may serve as an alternative to CT and MRI in the management of select patients with hydrocephalus and CSF disorders.

Pediatric ventriculoperitoneal shunt: a comparative study between anterior fontanel ultrasound-guided versus conventional cranial end insertion

PURPOSE

Ventriculoperitoneal (V-P) shunt is one of the most common neurosurgical procedures in pediatrics for the treatment of hydrocephalus. Shunt failure is one of the common mechanical complications which lead to major morbidities. This study aims to compare between cranial part insertions of the V-P shunts guided by trans-anterior fontanel ultrasound versus conventional insertion.

METHODS

A prospective comparative randomized study was conducted on 60 pediatric patients aged ≤ 2 years who suffered hydrocephalus and allocated into 2 groups. In the first group (n = 30), the cranial parts of the ventriculoperitoneal shunts were inserted guided by trans-anterior fontanel ultrasound, and in the second group (n = 30), the insertions were by the conventional method. The follow-up duration of the patients was 3 months.

RESULTS

Proximal part obstruction of the V-P shunt was found in 3 cases of the conventional group during follow-up with statistical insignificance (p = 0.237) while adequate proximal part location recorded statistical significance (p = 0.0005) in favor of ultrasound-guided group.

CONCLUSION

The use of the anterior fontanel ultrasound guide during ventriculoperitoneal shunt insertion is a feasible, safe, and effective technique for the placement of ventricular catheters in pediatric patients with a patent anterior fontanel.

Global Irradiation in Children Treated for Hydrocephalus and Its Change over Time—A Single Institutional Analysis

Radiation exposure early in life is associated with greater incidences of malignancy. Our goal was to quantify radiation exposure in shunt-treated hydrocephalus patients and study changes in the diagnostic modalities used. A single-center, retrospective analysis was performed, and 41 children treated for hydrocephalus using an adjustable ventriculoperitoneal shunt were identified. Diagnostics associated with hydrocephalus and other comorbidities were analyzed and radiation exposure was calculated. During 330.09 total shunt years, patients were exposed to a mean hydrocephalus-associated radiation dose of 3.93 mSv (range: 0–24.38 mSv), which amounted to a mean rate of 0.49 mSv per shunt year, respectively. Radiation exposure was greatest after shunt insertion in the first year of life. A continuous change from CT scans to MRIs could be seen over the study period, such that patients who underwent shunt insertion after 2017 were not exposed to additional hydrocephalus-associated radiation during their first year of life. Nevertheless, our patients, and a few individuals especially, seemed to be at higher risk for radiation sequelae. Our results suggest that CT scans should be substituted with MRIs, which decrease overall radiation exposure and can lead to zero additional radiation exposure during the first year of life after shunt insertion.

Accuracy of Pedicle Screw Placement Methods in Pediatrics and Adolescents Spinal Surgery: A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVE

Various methods of pedicle screw (PS) placement in spinal fusion surgery existed, which can be grouped into conventional freehand (FH), modified freehand (MF), and image-guided methods (including fluoroscopy-based navigation (FL), computed tomography-based navigation (CT-nav), robot-assisted (RA), and ultrasound-guided (UG)). However, the literature showed mixed findings regarding their accuracy and complications. This review aimed to discover which method of PS placement has the highest accuracy and lowest complication rate in pediatric and adolescent spinal fusion surgery.

METHODS

A comprehensive search in MEDLINE (PubMed), EMBASE (OVID), CENTRAL, and Web of Science was conducted until May 2020 by 2 independent reviewers, followed by bias assessment with ROB 2 and ROBINS-I tools and quantification with meta-analysis. Overall evidence quality was determined with GRADE tool.

RESULTS

Four RCTs and 2 quasi-RCTs/CCTs comprising 3,830 PS placed in 291 patients (4-22 years old) were analyzed. The lowest accuracy was found in FH (78.35%) while the highest accuracy was found in MF (95.86%). MF was more accurate than FH (OR 3.34 (95% CI, 2.33-4.79), P < .00 001, I² = 0%). Three-dimensional printed drill template (as part of MF) was more accurate than FH (OR 3.10 (95% CI, 1.98-4.86), P < .00 001, I² = 14%). Overall, complications occurred in 5.84% of the patients with 0.34% revision rate. Complication events in MF was lower compared to FH (OR 0.47 (95% CI, 0.10-2.15), P = .33, I² = 0%).

CONCLUSIONS

Meta-analysis shows that MF is more accurate than FH in pediatric and adolescent requiring PS placement for spinal fusion surgery.

Variation in radiation dosing among pediatric trauma patients undergoing head computed tomography scan

BACKGROUND

When head injured children undergo head computed tomography (CT), radiation dosing can vary considerably between institutions, potentially exposing children to excess radiation, increasing risk for malignancies later in life. We compared radiation delivery from head CTs at a level 1 pediatric trauma center (PTC) versus scans performed at referring adult general hospitals (AGHs). We hypothesized that children at our PTC receive a significantly lower radiation dose than children who underwent CT at AGHs for similar injury profiles.

METHODS

We retrospectively reviewed the charts of all patients younger than 18 years who underwent CT for head injury at our PTC or at an AGH before transfer between January 1 and December 31, 2019. We analyzed demographic and clinical data. Our primary outcome was head CT radiation dose, as calculated by volumetric CT dose index (CTDIvol) and dose-length product (DLP; the product of CTDIvol and scan length). We used unadjusted bivariate and multivariable linear regression (adjusting for age, weight, sex) to compare doses between Children's Hospital Los Angeles and AGHs.

RESULTS

Of 429 scans reviewed, 193 were performed at our PTC, while 236 were performed at AGHs. Mean radiation dose administered was significantly lower at our PTC compared with AGHs (CTDIvol 20.3/DLP 408.7 vs. CTDIvol 30.6/DLP 533, p < 0.0001). This was true whether the AGH was a trauma center or not. After adjusting for covariates, findings were similar for both CTDIvol and DLP. Patients who underwent initial CT at an AGH and then underwent a second CT at our PTC received less radiation for the second CT (CTDIvol 25.6 vs. 36.5, p < 0.0001).

CONCLUSIONS

Head-injured children consistently receive a lower radiation dose when undergoing initial head CT at a PTC compared with AGHs. This provides a basis for programs aimed at establishing protocols to deliver only as much radiation as necessary to children undergoing head CT.

LEVEL OF EVIDENCE

Care Management/Therapeutic, level IV.