Evaluation of ultra-low dose CT in the diagnosis of pediatric-like fractures using an experimental animal study

Effectiveness of low dose computed tomography to detect fractures in paediatric suspected physical abuse: a systematic review

PURPOSE

The skeletal survey X-ray series is the current 'gold standard' when investigating suspected physical abuse (SPA) of children, in addition to a non-contrast computed tomography (CT) brain scan. This systematic literature review synthesised findings of published research to determine if low dose computed tomography (LDCT) could detect subtle fractures and therefore replace the skeletal survey X-ray series in the investigation of SPA in children aged under 3 years.

METHODS

Five electronic databases and grey literature were systematically searched from their inception to 28 April 2022. Primary studies were included where the population comprised paediatric patients up to 16 years and LDCT was used to detect fractures associated with SPA. Studies involving imaging investigations of the head, standard dose CT examinations or accidental trauma were excluded.

RESULTS

Three studies met the inclusion criteria, all of which were case series. These studies did not report many of the criteria required to compare the accuracy of LDCT to X-ray, i.e. they did not meet the criteria for a diagnostic accuracy test. Therefore, it is difficult to conclude from the case series if LDCT is accurate enough to replace X-rays.

CONCLUSION

Due to the gap in current literature, a phantom study and subsequent post-mortem CT study are recommended as the primary investigative methods to assess the ability of low-dose CT to identify the subtle fractures associated with SPA and to calculate how low the achievable CT dose can be.

Clinical value of low-dose three-dimensional reconstruction by multi-slice spiral computed tomography and by traditional X-ray in the diagnosis of distal radius epiphyseal injury in children

OBJECTIVE

To compare the clinical value of multi-slice spiral computed tomography (MSCT) low-dose three-dimensional reconstruction and traditional X-ray in the auxiliary diagnosis of distal radius epiphyseal injury in children.

METHODS

A retrospective analysis was performed on 105 children with distal radius bone scale injury (classified by Salter-Harris classification) admitted from March 2020 to June 2022. All children underwent MSCT three-dimensional reconstruction examination and traditional X-ray examination. The detection rate of epiphyseal injury of the distal radius was compared, along with the resolution, sensitivity and specificity. The image clarity and display degree of bone structure were analyzed. The radiation dose-related indicators and the time required for diagnosis were compared.

RESULTS

The detection rate and diagnostic accuracy of MSCT (100%, 92.38%) was significantly higher than that of X-ray (76.19%, 64.76%). In terms of radiation dose index, the volume dose index CTDI of MSCT ranged from 1-5 mGy while the X-ray group ranged from 5-10 mGy. The dose length product (DLP) value of the MSCT group was lower than in the X-ray group (20-100 mGy·cm vs. 50-150 mGy·cm). The diagnostic scan time for MSCT was shorter than that of conventional X-ray. The acceptance rate with MSCT was 99%, significantly higher than that with conventional X-ray (85%).

CONCLUSIONS

Low-dose three-dimensional reconstruction of MSCT in the diagnosis of epiphyseal injury of distal radius in children shows significant advantages over traditional CT in the detection rate, diagnostic accuracy, postoperative reduction quality evaluation, and radiation dose.

Ultra-low-dose CT is feasible for torsion measurement of the lower limb in patients with metal implants

OBJECTIVES

Patients who need torsion measurement of the lower limb often have metal implants hindering e.g. MRI. A new ultra-low-dose (ULD-)CT protocol might be feasible for torsion measurement at cost of relatively low radiation exposure.

METHODS

We retrospectively included all patients with clinically indicated torsion measurement in the period July 2019 to June 2021 and metal implants in the scanning field. The ULD-CT protocol comprised automated tube current time product and automated tube voltage with reference settings of 100kV/20mAs (hip), 80kV/20mAs (knee) and 80kV/10mAs (ankle). Femoral neck anteversion, tibial, intra-articular knee and overall leg torsion measurements were performed by two radiologists independently. Diagnostic confidence regarding the delineation of the relevant cortical bone was rated on a 5-point Likert scale (1 = non-diagnostic, 5 = excellent).

RESULTS

102 consecutive patients could be included (BMI 27.38 ± 5.85) with 154 metal implants. Median total dose length product of the ULD-CT-torsion measurement was 16.5mGycm [11-39]. Both readers showed high agreement with a maximum torsional difference of 4.1°. Diagnostic confidence was rated best (5/5) in 92.2% (reader 1) and 93.1% (reader 2) with a worst rating of 3/5.

CONCLUSION

The new ULD-CT protocol is feasible for torsion measurement of the lower limb - even in patients with metal implants.

ADVANCES IN KNOWLEDGE

Metal implants are not an obstacle for ULD-CT torsion measurements of the lower limb.

Ultra-low-dose computed tomography and its utility in wrist trauma in the emergency department

BACKGROUND

The use and frequency of computed tomography (CT) are increasing day by day in emergency departments (ED). This increases the amount of radiation exposed.

PURPOSE

To evaluate the image quality obtained by ultra-low-dose CT (ULDCT) in patients with suspected wrist fractures in the ED and to investigate whether it is an alternative to standard-dose CT (SDCT).

MATERIAL AND METHODS

This is a study prospectively examining 336 patients who consulted the ED for wrist trauma. After exclusion criteria were applied, the patients were divided into the study and control groups. Then, SDCT (120 kVp and 100 mAs) and ULDCT (80 kVp and 5 mAs) wrist protocols were applied simultaneously. The images obtained were evaluated for image quality and fracture independently by a radiologist and an emergency medical specialist using a 5-point scale.

RESULTS

The effective radiation dose calculated for the control group scans was 41.1 ± 2.1 µSv, whereas the effective radiation dose calculated for the study group scans was 0.5 ± 0.0 µSv. The effective radiation dose of the study group was significantly lower than that of the control group (P < 0.01). The CT images in the study group showed no significant differences in the mean image quality score between observer 1 and observer 2 (3.4 and 4.3, respectively; P = 0.58). Both observers could detect all fractures using the ULDCT images.

CONCLUSION

ULDCT provides high-quality images in wrist traumas while reducing the radiation dose by approximately 98% compared to SDCT without any changes in diagnostic accuracy.

Postoperative Computed Tomography for Facial Fractures

In order for a radiologist to create reports that are meaningful to facial reconstructive surgeons, an understanding of the principles that guide surgical management and the hardware employed is imperative. This article is intended to promote efficient and salient reporting by illustrating surgical approaches and rationale. Hardware selection can be inferred and a defined set of potential complications anticipated when assessing the adequacy of surgical reconstruction on postoperative computed tomography for midface, internal orbital, and mandible fractures.

Computed tomography with low-dose radiation versus standard-dose radiation for diagnosing fractures: systematic review and meta-analysis

BACKGROUND

Computed tomography (CT) accounts for 13% of all radiological examinations in the United States and 40-70% of the radiation that patients receive. Even with the advent of magnetic resonance imaging (MRI), CT continues to be the gold standard for diagnosing bone fractures. There is uncertainty as to whether CT with a low radiation dose has a fracture detection rate similar to that of standard-dose CT.

OBJECTIVE

To determine the detection rate of low-dose radiation CT and standard-dose radiation CT for fractures, in patients with suspected fractures.

DESIGN AND SETTING

Systematic review of comparative studies on diagnostic accuracy within the evidence-based health program at a federal university in São Paulo (SP), Brazil.

METHODS

We searched the electronic databases Cochrane Library, MEDLINE, EMBASE and LILACS up to June 29, 2020, for studies evaluating the detection rates of low-dose CT and standard-dose CT for diagnosing bone fractures. The Research Triangle Institute (RTI) item bank tool was used for methodological quality evaluation.

RESULTS

The fracture detection rate according to the number of bones evaluated, using CT with low-dose radiation was 20.3%, while with standard-dose radiation it was 19.2%, and the difference between the methods was not significant. The fracture detection rate according to the number of patients, using CT with low-dose radiation was 56.0%, while with standard-dose radiation it was 58.7%, and this difference between the methods was not significant, either.

CONCLUSION

CT with low-dose radiation presented detection rates similar to those of CT with standard-dose radiation, regardless of the bones evaluated.

REGISTRATION NUMBER

CRD42019148491 at the PROSPERO database.

New and emerging patient-centered CT imaging and image-guided treatment paradigms for maxillofacial trauma

This article reviews the conceptual framework, available evidence, and practical considerations pertaining to nascent and emerging advances in patient-centered CT-imaging and CT-guided surgery for maxillofacial trauma. These include cinematic rendering-a novel method for advanced 3D visualization, incorporation of quantitative CT imaging into the assessment of orbital fractures, low-dose CT imaging protocols made possible with contemporary scanners and reconstruction techniques, the rapidly growing use of cone-beam CT, virtual fracture reduction with design software for surgical pre-planning, the use of 3D printing for fabricating models and implants, and new avenues in CT-guided computer-aided surgery.

Radiation dose reduction in multidetector CT in fracture evaluation

OBJECTIVE

To evaluate whether multidetector CT with low-dose radiation (low-dose CT) of joints can be useful when evaluating fractures.

METHODS

Our study included CT scans of 398 patients, 103 shoulder cases, 109 wrist cases, 98 pelvis cases and 88 ankle cases. There were 191 females and 207 males. The low-dose CTs were performed using identical voltage and parameters with the exception of decreased (half of standard dose) tube current. Low-dose and standard-dose images were compared with regards to objective image quality, subjective evaluation of image quality and diagnostic performance for the fractures.

RESULTS

There was no significant difference of image noise between standard-dose CT and low-dose CT in every joint (p > 0.05). Each mean value of subjective score did not show significant difference according to the dosage of the CT scan. There were no statistically significant differences in the sensitivity (96-100%), specificity (95.2-100%) or accuracy (97.9-100%) between standard-dose CT and low-dose CT (p values, 0.1336-1.000).

CONCLUSION

The evaluation of extremities for fractures using low-dose CT can reduce radiation exposure by about 50% compared with standard-dose CT without affecting image quality or diagnostic performance. Advances in knowledge: Low-dose CT of the extremities (shoulder, pelvis, ankle and wrist) can reduce radiation dose by about 50% compared with standard-dose CT and does not significantly affect image quality or diagnostic performance in fracture detection.

Usefulness of low dose chest CT for initial evaluation of blunt chest trauma

We aimed to compare the diagnostic performance and inter-observer consistency between low dose chest CT (LDCT) and standard dose chest CT (SDCT) in the patients with blunt chest trauma.A total of 69 patients who met criteria indicative of blunt chest trauma (77% of male; age range, 16-85) were enrolled. All patients underwent LDCT without intravenous (IV) contrast and SDCT with IV contrast using parameters as following: LDCT, 40 mAs with automatic tube current modulation (ATCM) and 100 kVp (BMI <25, n = 51) or 120 kVp (BMI>25, n = 18); SDCT, 180 mAs with ATCM and 120 kVp. Transverse, coronal, sagittal images were reconstructed with 3-mm slice thickness without gap and provided for evaluation of 3 observers. Reference standard images (transverse, coronal, sagittal) were reconstructed using SDCT data with 1-mm slice thickness without gap. Reference standard was established by 2 experienced thoracic radiologists by consensus. Three observers independently evaluated each data set of LDCT and SDCT.Multiple-reader receiver operating characteristic analysis for comparing areas under the ROC curves demonstrated that there was no significant difference of diagnostic performance between LDCT and SDCT for the diagnosis of pulmonary injury, skeletal trauma, mediastinal injury, and chest wall injury (P > 0.05). The intraclass correlation coefficient was measured for inter-observer consistency and revealed that there was good inter-observer consistency in each examination of LDCT and SDCT for evaluation of blunt chest injury (0.8601-1.000). Aortic and upper abdominal injury could not be appropriately compared as LDCT was performed without using contrast materials and this was limitation of this study.The effective radiation dose of LDCT (average DLP = 1.52 mSv⋅mGy cm) was significantly lower than those of SDCT (7.21 mSv mGy cm).There is a great potential benefit to use of LDCT for initial evaluation of blunt chest trauma because LDCT could maintain diagnostic image quality as SDCT and provide significant radiation dose reduction. A further study of LDCT with IV contrast for evaluation of aortic and upper abdominal injury is needed.

Ultralow-dose computed tomography imaging for surgery of midfacial and orbital fractures using ASIR and MBIR

The influence of dose reductions on diagnostic quality using a series of high-resolution ultralow-dose computed tomography (CT) scans for computer-assisted planning and surgery including the most recent iterative reconstruction algorithms was evaluated and compared with the fracture detectability of a standard cranial emergency protocol. A human cadaver head including the mandible was artificially prepared with midfacial and orbital fractures and scanned using a 64-multislice CT scanner. The CT dose index volume (CTDIvol) and effective doses were calculated using application software. Noise was evaluated as the standard deviation in Hounsfield units within an identical region of interest in the posterior fossa. Diagnostic quality was assessed by consensus reading of a craniomaxillofacial surgeon and radiologist. Compared with the emergency protocol at CTDIvol 35.3 mGy and effective dose 3.6 mSv, low-dose protocols down to CTDIvol 1.0 mGy and 0.1 mSv (97% dose reduction) may be sufficient for the diagnosis of dislocated craniofacial fractures. Non-dislocated fractures may be detected at CTDIvol 2.6 mGy and 0.3 mSv (93% dose reduction). Adaptive statistical iterative reconstruction (ASIR) 50 and 100 reduced average noise by 30% and 56%, and model-based iterative reconstruction (MBIR) by 93%. However, the detection rate of fractures could not be improved due to smoothing effects.

Multidetector computed tomography for the assessment of adnexal mass: is unenhanced CT scan necessary?

OBJECTIVE

To compare the diagnostic performance and radiation dose between contrast-enhanced CT (ECT) alone, and combined unenhanced and contrast-enhanced CT (UE + ECT) for the assessment of adnexal mass.

MATERIALS AND METHODS

This retrospective study was approved by the Institutional Review Board. A total of 146 consecutive patients (mean age, 41.1 years) who underwent preoperative unenhanced and contrast-enhanced multidetector CT of the pelvis and had adnexal masses found at surgery were included. Two readers independently evaluated the likelihood of adnexal malignancy on a 5-point scale on two different imaging datasets (ECT alone and UE + ECT). The area under the receiver operating characteristic curve (AUC) was used to evaluate diagnostic performance. Radiation dose to patients was calculated by the volume CT dose index (CTDIvol) and the dose length products (DLP) on each dataset.

RESULTS

Of the total 178 adnexal masses, 133 masses were benign and 45 masses were malignant. For both readers, there is no significant difference of AUC values between ECT alone and UE + ECT for the detection of adnexal malignancy (reader 1, 0.93 vs. 0.95; reader 2, 0.92 vs. 0.91) (p > 0.05). The mean CTDIvol (12.6 ± 2.2 mGy) and DLP (641.2 ± 137.2 mGy) of ECT alone was significantly lower than the mean CTDIvol (21.5 ± 2.7 mGy) and DLP (923.6 ± 158.8 mGy) of UE + ECT (p < 0.0001).

CONCLUSION

The use of unenhanced CT scan in addition to contrast-enhanced CT scan does not improve the detection of adnexal malignancy, but increases radiation exposure.

Radiation dose reduction via sinogram affirmed iterative reconstruction and automatic tube voltage modulation (CARE kV) in abdominal CT

Objective

To evaluate the feasibility of sinogram-affirmed iterative reconstruction (SAFIRE) and automated kV modulation (CARE kV) in reducing radiation dose without increasing image noise for abdominal CT examination.

Materials and Methods

This retrospective study included 77 patients who received CT imaging with an application of CARE kV with or without SAFIRE and who had comparable previous CT images obtained without CARE kV or SAFIRE, using the standard dose (i.e., reference mAs of 240) on an identical CT scanner and reconstructed with filtered back projection (FBP) within 1 year. Patients were divided into two groups: group A (33 patients, CT scanned with CARE kV); and group B (44 patients, scanned after reducing the reference mAs from 240 to 170 and applying both CARE kV and SAFIRE). CT number, image noise for four organs and radiation dose were compared among the two groups.

Results

Image noise increased after CARE kV application (p < 0.001) and significantly decreased as SAFIRE strength increased (p < 0.001). Image noise with reduced-mAs scan (170 mAs) in group B became similar to that of standard-dose FBP images after applying CARE kV and SAFIRE strengths of 3 or 4 when measured in the aorta, liver or muscle (p ≥ 0.108). Effective doses decreased by 19.4% and 41.3% for groups A and B, respectively (all, p < 0.001) after application of CARE kV with or without SAFIRE.

Conclusion

Combining CARE kV, reduction of mAs from 240 to 170 mAs and noise reduction by applying SAFIRE strength 3 or 4 reduced the radiation dose by 41.3% without increasing image noise compared with the standard-dose FBP images.