Associated (Parallel) Tomographic Findings in Patients With Single-Sutural Synostosis

Evaluation of ultra-low-dose CT with tin filter for craniosynostosis

INTRODUCTION

CT has replaced skull radiography as the gold standard for assessment of craniosynostosis in children. To minimise the risks of ionising radiation in this radiosensitive population, low-dose CT protocols are increasingly being adopted. This study evaluates the effectiveness of an ultra-low-dose CT protocol with a tin filter in reducing radiation exposure whilst maintaining diagnostic quality for craniosynostosis, and its utility in the evaluation of other findings not appreciable on skull radiography.

METHODS

Twenty-seven patients who underwent ultra-low-dose CT for craniosynostosis were compared with an age-matched control group who received standard-dose CT for indications other than craniosynostosis. Differences in radiation dosimetry and quantitative image quality parameters were analysed using independent two-tailed t-tests. Radiologist reports were also examined for the frequency of other incidental radiological findings.

RESULTS

Mean effective dose for the 27 ultra-low-dose CT scans was 0.14 mSv, a 92% reduction compared with the control group. Image quality, measured by contrast-to-noise ratio, was significantly lower in the ultra-low-dose scans compared with the standard-dose scans; however, all scans were diagnostic for detecting or excluding craniosynostosis. Hydrocephalus was able to be ruled out in all 27 ultra-low-dose scans.

CONCLUSION

Ultra-low-dose CT with a tin filter allows for the diagnosis of craniosynostosis with a 92% dose reduction compared with the standard CT protocol. Despite lower image quality with the ultra-low-dose protocol when compared to standard CT, all 27 scans were adequate for craniosynostosis diagnosis. Additionally, it allowed for the assessment of other relevant findings not appreciable with skull radiography, highlighting its advantages as the new clinical standard for craniosynostosis assessment.

Preoperative imaging patterns and intracranial findings in single-suture craniosynostosis: a study from the Synostosis Research Group

OBJECTIVE

The diagnosis of single-suture craniosynostosis can be made by physical examination, but the use of confirmatory imaging is common practice. The authors sought to investigate preoperative imaging use and to describe intracranial findings in children with single-suture synostosis from a large, prospective multicenter cohort.

METHODS

In this study from the Synostosis Research Group, the study population included children with clinically diagnosed single-suture synostosis between March 1, 2017, and October 31, 2020, at 5 institutions. The primary analysis correlated the clinical diagnosis and imaging diagnosis; secondary outcomes included intracranial findings by pathological suture type.

RESULTS

A total of 403 children (67% male) were identified with single-suture synostosis. Sagittal (n = 267), metopic (n = 77), coronal (n = 52), and lambdoid (n = 7) synostoses were reported; the most common presentation was abnormal head shape (97%), followed by a palpable or visible ridge (37%). Preoperative cranial imaging was performed in 90% of children; findings on 97% of these imaging studies matched the initial clinical diagnosis. Thirty-one additional fused sutures were identified in 18 children (5%) that differed from the clinical diagnosis. The most commonly used imaging modality by far was CT (n = 360), followed by radiography (n = 9) and MRI (n = 7). Most preoperative imaging was ordered as part of a protocolized pathway (67%); some images were obtained as a result of a nondiagnostic clinical examination (5.2%). Of the 360 patients who had CT imaging, 150 underwent total cranial vault surgery and 210 underwent strip craniectomy. The imaging findings influenced the surgical treatment 0.95% of the time. Among the 24% of children with additional (nonsynostosis) abnormal findings on CT, only 3.5% required further monitoring.

CONCLUSIONS

The authors found that a clinical diagnosis of single-suture craniosynostosis and the findings on CT were the same with rare exceptions. CT imaging very rarely altered the surgical treatment of children with single-suture synostosis.

Otitis Media and Hearing Loss in Patients With Nonsyndromic Craniosynostosis: A Multicenter Study

OBJECTIVES

The objectives of this study were to: (1) determine the prevalence of otitis media with effusion in patients with nonsyndromic craniosynostosis; (2) determine the prevalence of hearing loss in patients with nonsyndromic craniosynostosis; and (3) identify potential patterns and outcomes in patients with nonsyndromic craniosynostosis.

METHODS

A retrospective chart review was conducted at 2 academic institutions, St Christopher's Hospital for Children and SUNY Upstate Medical University, from January 2015 through August 2018, to identify patients having nonsyndromic craniosynostosis with a concurrent diagnosis of otitis media and/or hearing loss. The demographic data and categorical variables were analyzed using descriptive statistics and chi-square testing, respectively.

RESULTS

In the entire cohort of patients (N = 113, age range 0-123 months), 36% had otitis media with effusion on either history, physical examination, tympanometry, and/or imaging. Half (50%) of patients with coronal synostosis had otitis media with effusion compared to sagittal (40.7%), metopic (26.3%), multiple (25%), and lambdoid (0%). However, these differences were not statistically significant (P = .190). Most patients had normal hearing (91%), while a minority had either conductive (7%) or sensorineural (2%) hearing loss.

CONCLUSION

The presence of otitis media in our cohort of patients with nonsyndromic craniosynostosis appears to be at the upper limit of normal when compared to historical rates in normocephalic children. Synostosis subtype did not appear to predict the presence of otitis media. Only 9% of patients with nonsyndromic craniosynostosis were found to have a hearing loss.

The Role of Preoperative Computed Tomography in Nonsyndromic Craniosynostosis

BACKGROUND

There is currently no consensus on the utility of preoperative computed tomography (CT) in nonsyndromic craniosynostosis. This systematic review and meta-analysis examines the evidence available on the necessity of preoperative CT for the treatment of nonsyndromic craniosynostosis.

METHODS

A comprehensive literature review of the National Library of Medicine (PubMed) database was performed. The following variables were analyzed: concordance of findings between clinical examinations and CT, incidental findings reported on imaging, and the effect of imaging on subsequent management. Concordance between clinical examination/CT and the presence of incidental findings were collected and displayed as descriptive data. The effect of imaging on subsequent diagnosis/management was analyzed by meta-analysis.

RESULTS

Eleven studies met the inclusion criteria for a total of 728 patients. Overall, physical examination concordance with CT diagnosis was 97.9% (371/379). Overall, incidental findings led to additional imaging/workup in 1.79% of cases (5/278). The results of the meta-analysis revealed that, in the absence of alternative imaging modalities, CT scans significantly altered diagnosis or led to additional investigations in 12 cases (4.8%, 95% confidence interval = 3%-8%). Preoperative CT scans led to additional investigations in 5 cases and detected incomplete/wrong diagnoses in 7 cases.

CONCLUSIONS

The results of the present meta-analysis support the use of preoperative CT scans for nonsyndromic craniosynostosis in the absence of alternative imaging modalities. The results also suggest that in properly selected patients, alternative imaging modalities may be appropriate, potentially obviating the need for CT scans.

Comparing the Use of 3D Photogrammetry and Computed Tomography in Assessing the Severity of Single-Suture Nonsyndromic Craniosynostosis

PURPOSE

Single-suture nonsyndromic craniosynostosis is diagnosed using clinical assessment and computed tomography (CT). With increasing awareness of the associated risks of radiation exposure, the use of CT is particularly concerning in patients with craniosynostosis since they are exposed at a younger age and more frequently than the average child. Three-dimensional (3D) photogrammetry is advantageous-it involves no radiation, is conveniently obtainable within clinic, and does not require general anaesthesia. This study aims to assess how 3D photogrammetry compares to CT in the assessment of craniosynostosis severity, to quantify surgical outcomes, and analyze the validity of 3D photogrammetry in craniosynostosis.

METHODS

Computed tomography images and 3D photographs of patients who underwent craniosynostosis surgery were assessed and aligned to best fit. The intervening area between the CT and 3D photogrammetry curves at the supraorbital bar (bandeau) level in axial view was calculated. Statistical analysis was performed using Student t test. Ninety-five percent confidence intervals were determined and equivalence margins were applied.

RESULTS

In total, 41 pairs of CTs and 3D photographs were analyzed. The 95% confidence interval was 198.16 to 264.18 mm² and the mean was 231.17 mm². When comparisons were made in the same bandeau region omitting the temporalis muscle, the 95% confidence interval was 108.94 to 147.38 mm², and the mean was 128.16 mm². Although statistically significant difference between the modalities was found, they can be attributable to the dampening effect of soft tissue.

CONCLUSION

Within certain error margins, 3D photogrammetry is comparable to CT in assessing the severity of single-suture nonsyndromic craniosynostosis. However, a dampening effect can be attributable to the soft tissue. Three-dimensional photogrammetry may be more applicable for severe cases of craniosynostosis but not milder deformity. It may also be beneficial for assessing the overall appearance and aesthetics but not for determining underlying bony severity.

Photometric evaluation of cranial and facial symmetry in hemicoronal single suture synostosis treated with surgical fronto-orbital remodeling

OBJECTIVE

Evaluation of frontal vault symmetry and progressive facial symmetrization in a cohort of patients with hemicoronal single suture synostosis treated with a standardized cranioplasty and rigid fixation.

PATIENTS AND METHODS

Fifty-four patients with hemicoronal synostosis operated between 1999 and 2014 were reviewed retrospectively. Pre, immediately postoperative and yearly photographs from the top of the skull and frontal views of the face were taken with the same head position and projection. A photogrammetric method was applied to quantify the pre and postoperative contour changes. The anterior skull hemispheres were traced, divided into two equal parts and the areas were compared. Angular measurements obtained by the intersection of the interpupillary line and the glabella perpendicular vertical line were calculated. The average photographic follow-up was 6.8 years. Range 1-14 years.

RESULTS

The average advancement on the affected side was 18 mm (range: 16-23 mm). The pre-surgical cranial area on the affected side was increased on average 14.6 + 2.4% (range: 10-18%). The angular measurements documented the frontal symmetry obtained and the progressive improvement of facial symmetry.

CONCLUSION

Cranioplasty with rigid fixation achieved a stable correction of anterior plagiocephaly leading to subsequent symmetrical facial growth. Photogrammetry allowed fora quantitative long-term validation.

Skull base development and craniosynostosis

Abnormal skull shape resulting in craniofacial deformity is a relatively common clinical finding, with deformity either positional (positional plagiocephaly) or related to premature ossification and fusion of the skull sutures (craniosynostosis). Growth restriction occurring at a stenosed suture is associated with exaggerated growth at the open sutures, resulting in fairly predictable craniofacial phenotypes in single-suture non-syndromic pathologies. Multi-suture syndromic subtypes are not so easy to understand without imaging. Imaging is performed to define the site and extent of craniosynostosis, to determine the presence or absence of underlying brain anomalies, and to evaluate both pre- and postoperative complications of craniosynostosis. Evidence for intracranial hypertension may be seen both pre- and postoperatively, associated with jugular foraminal stenosis, sinovenous occlusion, hydrocephalus and Chiari 1 malformations. Following clinical assessment, imaging evaluation may include radiographs, high-frequency US of the involved sutures, low-dose (20-30 mAs) CT with three-dimensional reformatted images, MRI and nuclear medicine brain imaging. Anomalous or vigorous collateral venous drainage may be mapped preoperatively with CT or MR venography or catheter angiography.

Value of preoperative imaging in the diagnostics of isolated metopic suture synostosis: a risk-benefit analysis

Radiographic evaluation including plain radiographies and computed tomographic (CT) scans are considered as a necessary tool for diagnosis of craniosynostosis. As recently concerns about harmful effects of ionising radiation in children have been raised, some authors have suggested the use of magnetic resonance imaging (MRI) as a helpful alternative in preoperative imaging of patients with isolated metopic synostosis. Besides confirming the diagnosis of trigonocephaly, MRI is the superior technique for the evaluation of underlying brain anomalies. However, if the benefit of preoperative imaging justifies possible side effects is still discussed controversially. Hence, this study investigated the value of preoperative imaging for the diagnosis of isolated synostosis of the metopic suture compared to a sole clinical examination. In a series of 63 cases with isolated metopic craniosynostosis operated at the Department of Oral and Maxillofacial Surgery, 48 (76.2%) patients received additional radiography or MRI investigation, while in 15 (23.8%) patients the diagnosis was based on clinical examinations only. In all patients, diagnosis was confirmed intra-operatively by a fused metopic suture. CT scans with three-dimensional reconstruction (12.5%) or plain radiographs (39.6%) did not provide any additional benefit for the diagnosis or the surgical treatment. In 23 patients (47.9%), MRI showed the typical soft-tissue alterations like triangular brain deformation in the frontal area. Besides these findings, no brain or other underlying anomalies were diagnosed which had required any additional treatment. The incidence of underlying brain abnormalities in isolated metopic synostosis seemed not to be different from that of the general population. As the characteristic clinical manifestations were sufficient for an accurate diagnosis of isolated metopic synostosis, and with respect to the biological effects of ionising radiation and risks of sedation especially in infants, preoperative imaging should be reduced to a minimum.