Cone-beam computed tomography: a new low dose, high resolution imaging technique of the wrist, presentation of three cases with technique

Cone-beam computed tomography in the treatment of distal radius fractures

Cone-beam computed tomography (CBCT) is a relatively new imaging technique in hand surgery. Being the most common fractures in adults, distal radius fractures are of special importance not only to hand surgeons. The quantity alone calls for fast, efficient and reliable diagnostic procedures. Surgical techniques and possibilities are progressing, especially regarding intra-articular fracture patterns. The demand for exact anatomic reduction is high. There is an overall consensus regarding the indication for preoperative three-dimensional imaging and it is frequently used. Typically, it is obtained by multi-detector computed tomography (MDCT). Postoperative diagnostic procedures are usually limited to plain x-rays. Commonly accepted recommendations regarding postoperative 3D imaging are not yet established. There is a lack of relevant literature. In case of an indication for a postoperative CT scan, it is generally also obtained by MDCT. CBCT for the wrist is not widely used as yet. This review focuses on the potential role of CBCT in the perioperative management of distal radius fractures. CBCT allows for high-resolution imaging with a potentially lower radiation dose compared with MDCT, both with and without implants. It is easily available and can be operated independently, thus being time-efficient and making daily practice easier. Due to its many advantages, CBCT is a recommendable alternative to MDCT in the perioperative management of distal radius fractures.

Photon-counting detector CT and energy-integrating detector CT for trabecular bone microstructure analysis of cubic specimens from human radius

Background

As bone microstructure is known to impact bone strength, the aim of this in vitro study was to evaluate if the emerging photon-counting detector computed tomography (PCD-CT) technique may be used for measurements of trabecular bone structures like thickness, separation, nodes, spacing and bone volume fraction.

Methods

Fourteen cubic sections of human radius were scanned with two multislice CT devices, one PCD-CT and one energy-integrating detector CT (EID-CT), using micro-CT as a reference standard. The protocols for PCD-CT and EID-CT were those recommended for inner- and middle-ear structures, although at higher mAs values: PCD-CT at 450 mAs and EID-CT at 600 (dose equivalent to PCD-CT) and 1000 mAs. Average measurements of the five bone parameters as well as dispersion measurements of thickness, separation and spacing were calculated using a three-dimensional automated region growing (ARG) algorithm. Spearman correlations with micro-CT were computed.

Results

Correlations with micro-CT, for PCD-CT and EID-CT, ranged from 0.64 to 0.98 for all parameters except for dispersion of thickness, which did not show a significant correlation (p = 0.078 to 0.892). PCD-CT had seven of the eight parameters with correlations ρ > 0.7 and three ρ > 0.9. The dose-equivalent EID-CT instead had four parameters with correlations ρ > 0.7 and only one ρ > 0.9.

Conclusions

In this in vitro study of radius specimens, strong correlations were found between trabecular bone structure parameters computed from PCD-CT data when compared to micro-CT. This suggests that PCD-CT might be useful for analysing bone microstructure in the peripheral human skeleton.

Radiological, Clinical and Functional Outcomes of Combined Dorsal and Volar Locking Plate Osteosynthesis for Complex Distal Radius Fractures

PURPOSE

The purpose of this study was to assess the short- to mid-term radiologic, clinical, and functional outcomes of patients treated with combined dorsal and volar locking plating for internal fixation of complex, comminuted, intra-articular, distal radius fractures.

METHODS

We performed a retrospective review of 34 patients treated with combined dorsal and volar locking plates for the internal fixation of complex, comminuted, intra-articular distal radius fractures. Radiographic and clinical parameters were recorded at a mean of 48 months after surgery. Activities of daily living and quality of life were assessed by the Disabilities of the Arm, Shoulder, and Hand and Patient-Rated Wrist Evaluation questionnaires.

RESULTS

Compared with the contralateral wrist, the treated wrist regained 73% of flexion, 81% of extension, 86% of ulnar deviation, 90% of radial deviation, 98% of pronation, 99% of supination, and 93% of grip strength. Mean Disabilities of the Arm, Shoulder, and Hand and Patient-Rated Wrist Evaluation scores were 11 (range, 0-78) and 11 (range, 0-77), respectively. Radial height and radial inclination were restored anatomically in 24% and 41% of patients, respectively, while volar tilt and ulnar variance were restored in 68% of patients.

CONCLUSION

The overall functional and radiologic outcome of patients with comminuted intra-articular complex distal radius fractures treated with the combined dorsovolar plate osteosynthesis was good to excellent.

LEVEL OF EVIDENCE

Therapeutic IV.

The effect of tin prefiltration on extremity cone-beam CT imaging with a twin robotic X-ray system

INTRODUCTION

While tin prefiltration is established in various CT applications, its value in extremity cone-beam CT relative to optimized spectra has not been thoroughly assessed thus far. This study aims to investigate the effect of tin filters in extremity cone-beam CT with a twin-robotic X-ray system.

METHODS

Wrist, elbow and ankle joints of two cadaveric specimens were examined in a laboratory setup with different combinations of prefiltration (copper, tin), tube voltage and current-time product. Image quality was assessed subjectively by five radiologists with Fleiss' kappa being computed to measure interrater agreement. To provide a semiquantitative criterion for image quality, contrast-to-noise ratios (CNR) were compared for standardized regions of interest. Volume CT dose indices were calculated for a 16 cm polymethylmethacrylate phantom.

RESULTS

Radiation dose ranged from 17.4 mGy in the clinical standard protocol without tin filter to as low as 0.7 mGy with tin prefiltration. Image quality ratings and CNR for tin-filtered scans with 100 kV were lower than for 80 kV studies with copper prefiltration despite higher dose (11.2 and 5.6 vs. 4.5 mGy; p < 0.001). No difference was ascertained between 100 kV scans with tin filtration and 60 kV copper-filtered scans with 75% dose reduction (subjective: p = 0.101; CNR: p = 0.706). Fleiss' kappa of 0.597 (95% confidence interval 0.567-0.626; p < 0.001) indicated moderate interrater agreement.

CONCLUSION

Considerable dose reduction is feasible with tin prefiltration, however, the twin-robotic X-ray system's low-dose potential for extremity 3D imaging is maximized with a dedicated low-kilovolt scan protocol in situations without extensive beam-hardening artifacts.

IMPLICATIONS FOR PRACTICE

Low-kilovolt imaging with copper prefiltration provides a superior trade-off between dose reduction and image quality compared to tin-filtered cone-beam CT scan protocols with higher tube voltage.

Evaluation of Ultra-High-Resolution Cone-Beam CT Prototype of Twin Robotic Radiography System for Cadaveric Wrist Imaging

RATIONALE AND OBJECTIVES

Cone-beam CT (CBCT) applications possess potential for dose reduction in musculoskeletal imaging. This study evaluates the ultra-high-resolution CBCT prototype of a twin robotic X-ray system in wrist examinations compared to high-resolution multidetector CT (MDCT).

MATERIALS AND METHODS

Sixteen wrists of body donors were examined with the CBCT scan mode and a 384 slice MDCT system. Radiation-equivalent low-dose (CTDI_vol(16cm)  = 3.3 mGy) and full-dose protocols (CTDI_vol(16cm)  = 13.8 mGy) were used for both systems. Two observers assessed image quality on a seven-point Likert scale. In addition, software-assisted quantification of signal intensity fractions in cancellous bone was performed. Fewer pixels with intermediate signal intensity were considered to indicate superior depiction of bone microarchitecture.

RESULTS

Subjective image quality in CBCT was superior to dose equivalent MDCT with p ≤ 0.03 for full-dose and p < 0.001 for low-dose scans, respectively. Median Likert values were 7/7 (reader 1 / reader 2) in full-dose CBCT, 6/6 in full-dose MDCT, 5/6 in low-dose CBCT and 3/3 in low-dose MDCT. Intraclass correlation coefficient was 0.936 (95% confidence interval, 0.897-0.961; p < 0.001), indicating excellent reliability. Objective analysis displayed smaller fractions of "indecisive" pixels with intermediate signal intensity for full-dose CBCT (0.57 [interquartile range 0.13]) compared to full-dose MDCT (0.68 [0.21]), low-dose CBCT (0.72 [0.19]), and low-dose MDCT (0.80 [0.15]) studies. No significant difference was observed between low-dose CBCT and full-dose MDCT.

CONCLUSION

The new CBCT prototype provides superior image quality for trabecula and bone marrow in cadaveric wrist studies and enables dose reduction up to 75% compared to high-resolution MDCT.

Advancements in Osteoporosis Imaging, Screening, and Study of Disease Etiology

PURPOSE OF REVIEW

The purpose of this review is to inform researchers and clinicians with the most recent imaging techniques that are employed (1) to opportunistically screen for osteoporosis and (2) to provide a better understanding into the disease etiology of osteoporosis.

RECENT FINDINGS

Phantomless calibration techniques for computed tomography (CT) may pave the way for better opportunistic osteoporosis screening and the retroactive analysis of imaging data. Additionally, hardware advances are enabling new applications of dual-energy CT and cone-beam CT to the study of bone. Advances in MRI sequences are also improving imaging evaluation of bone properties. Finally, the application of image registration techniques is enabling new uses of imaging to investigate soft tissue-bone interactions as well as bone turnover. While DXA remains the most prominent imaging tool for osteoporosis diagnosis, new imaging techniques are becoming more widely available and providing additional information to inform clinical decision-making.

High-Resolution Cone-Beam Computed Tomography is a Fast and Promising Technique to Quantify Bone Microstructure and Mechanics of the Distal Radius

Obtaining high-resolution scans of bones and joints for clinical applications is challenging. HR-pQCT is considered the best technology to acquire high-resolution images of the peripheral skeleton in vivo, but a breakthrough for widespread clinical applications is still lacking. Recently, we showed on trapezia that CBCT is a promising alternative providing a larger FOV at a shorter scanning time. The goals of this study were to evaluate the accuracy of CBCT in quantifying trabecular bone microstructural and predicted mechanical parameters of the distal radius, the most often investigated skeletal site with HR-pQCT, and to compare it with HR-pQCT. Nineteen radii were scanned with four scanners: (1) HR-pQCT (XtremeCT, Scanco Medical AG, @ (voxel size) 82 μm), (2) HR-pQCT (XtremeCT-II, Scanco, @60.7 μm), (3) CBCT (NewTom 5G, Cefla, @75 μm) reconstructed and segmented using in-house developed software and (4) microCT (VivaCT40, Scanco, @19 μm-gold standard). The following parameters were evaluated: predicted stiffness, strength, bone volume fraction (BV/TV) and trabecular thickness (Tb.Th), separation (Tb.Sp) and number (Tb.N). The overall accuracy of CBCT with in-house optimized algorithms in quantifying bone microstructural parameters was comparable (R² = 0.79) to XtremeCT (R² = 0.76) and slightly worse than XtremeCT-II (R² = 0.86) which were both processed with the standard manufacturer's technique. CBCT had higher accuracy for BV/TV and Tb.Th but lower for Tb.Sp and Tb.N compared to XtremeCT. Regarding the mechanical parameters, all scanners had high accuracy (R² [Formula: see text] 0.96). While HR-pQCT is optimized for research, the fast scanning time and good accuracy renders CBCT a promising technique for high-resolution clinical scanning.

Comparison of 3D X-ray tomography with computed tomography in patients with distal extremity fractures

OBJECTIVE

To compare fracture detection, image quality, and radiation dose in patients with distal extremity fractures using 3D tomography and computed tomography (CT).

MATERIALS AND METHODS

IRB approval was obtained including informed consent for this prospective study from June to December 2016. Patients diagnosed with an acute fracture at CT were consecutively scanned on the same day using 3D tomography. Anatomical location (effected bone and location within the bone) and morphological characteristics of fractures (avulsion, articular involvement, mono- vs. multifragmented, displacement), visibility of bone/soft tissue structures, and image quality were assessed independently by two blinded readers on a 5-point Likert scale. Dose-length-product (DLP; mGy*cm) was compared between both modalities. Descriptive statistics, Wilcoxon signed rank test (P < 0.05), Student's t test (P < 0.05), and Cohen's kappa (κ) for interreader reliability were calculated.

RESULTS

In 46 patients (28 males; 18 females; mean age, 53 ± 20 years) with 28 hand/wrist and 18 foot/ankle examinations, 86 out of 92 fractures were diagnosed with 3D tomography compared with CT. No false-positive finding occurred at 3D tomography. The six missed fractures on 3D tomography were five avulsion fractures of the carpals/metacarpals or tarsals/metatarsals, respectively, and one nondisplaced fracture of the capitate. Interreader agreement of anatomical location and morphological characteristics was substantial to almost perfect for upper (κ = 0.80-0.96) and lower (κ = 0.70-0.97) extremity fractures. Visibility of bone and soft tissue structures and image quality were slightly inferior using 3D tomography compared with CT (upper extremity P < 0.001-0.038 and lower extremity P < 0.001-0.035). DLP of a comparable scan coverage was significantly lower for 3D tomography (P < 0.001) for both upper (3D mean, 19.4 ± 5.9 mGy*cm; estimated CT mean, 336.5 ± 52.2 mGy*cm) and lower extremities (3D mean, 24.1 ± 11.1 mGy*cm; estimated CT mean, 182.9 ± 6.5 mGy*cm). Even the highest DLP with 3D tomography was < 30% of the mean estimated CT dose of a comparable area of coverage.

CONCLUSION

Fracture assessment of peripheral extremities is reliable utilizing a low-dose 3D tomography X-ray system, with slightly reduced image quality.

Evaluation of motion artifacts in cone-beam computed tomography with three different patient positioning

OBJECTIVES

Cone-beam computed tomography (CBCT), despite its advantages, has some drawbacks, such as artifacts and movement of the patient during scanning may lead to motion artifacts (MAs). This retrospective study aimed to evaluate the MAs in three different CBCT devices and to analyze their relationship with age, the gender of the patients, and scanning times.

METHODS

This study included 360 CBCT images from three institutions scanned in standing, sitting and supine positions. MAs presence, age, gender, and scanning times were recorded. Of the patients, 129 were scanned in standing position, 131 in sitting position, and 100 in supine position.

RESULTS

MAs were found in 6.7% of patients in total; 8%, 7.6%, and 4% in standing, sitting, and supine positions, respectively. No statistically significant relationship was observed between MAs presence and patient position. The mean age of the patients with MAs was higher than patients without, in total and in standing positions. Scanning time showed no correlation with artifact presence.

CONCLUSIONS

Patient position is not related to MAs presence. The age of the patient is a factor in movement, and has a high impact in standing position. Although insignificant, MAs were less common in supine position than sitting and standing positions. Sitting and supine positioning might reduce motion artifacts in older patients.

The Role of Cone-Beam Computed Tomography (CBCT) Scan for Detection and Follow-Up of Traumatic Wrist Pathologies

Emergency diagnostics demand fast, easily available, and cost-effective procedures. The higher the accuracy of radiological imaging, the better it supports the surgeon in decision-making for further treatment. Cone-beam computed tomography has been proven to be a reliable tool in diagnosing fractures of the hand and distal forearm. It can be easily installed, has a high spatial resolution, and a potentially lower radiation dose when compared with multislice computed tomography or a series of plain x-rays. This review focuses on the value of conventional radiography, cone-beam computed tomography, and multislice computed tomography for diagnosing traumatic wrist pathologies.

Correlation Between Cone-Beam Computed Tomography and High-Resolution Peripheral Computed Tomography for Assessment of Wrist Bone Microstructure

High-resolution peripheral quantitative computed tomography (HR-pQCT) is considered as the best technique to measure bone microarchitecture in vivo. However, a breakthrough for medical applications is inhibited because of the restricted field of view (∼9 mm) and a relatively long acquisition time (∼3 minutes). The goal of this study was to compare the accuracy of cone-beam computed tomography (CBCT) and HR-pQCT and to determine the agreement between CBCT and HR-pQCT in quantifying bone structural parameters. Nineteen trapezia of arthritic patients were scanned four times ex vivo: 1) CBCT (NewTom 5G, Cefla, at 75 μm); 2) HR-pQCT (XTremeCT-I, Scanco, at 82 μm); 3) HR-pQCT (XTremeCT-II, Scanco, at 60.7 μm); and 4) microCT (SkyScan1172, Bruker, at 19.84 μm). XTremeCT-I and XtremeCT-II were reconstructed, segmented, and analyzed following the manufacturer's guidelines. CBCT was reconstructed with in-house developed software and analyzed twice: once with an adaptive segmentation technique combined with a direct analysis method (AT-DM) and once with a Laplace-Hamming filtering technique combined with an indirect analysis method (LH-IM). Parameters of interest included bone volume fraction (BV/TV) and trabecular thickness (Tb.Th), separation (Tb.Sp), and number (Tb.N). The analyses of the CBCT data showed that the AT-DM analysis correlated better with microCT for BV/TV, Tb.Sp, and Tb.N, whereas the LH-IM technique correlated better for Tb.Th. Evaluated over all parameters, the coefficient of determination for XtremeCT-I, XtremeCT-II, and CBCT were higher as R²  = 0.68, 0.72, and 0.67, respectively. For CBCT, the correlations improved when three samples with very thin trabeculae close to each other were excluded and became similar to those for XtremeCT-I and XtremeCT-II. Interesting for clinical practice is that those bones could be identified automatically with the CBCT scanner. We conclude that CBCT produced similar accuracy as HR-pQCT in bone morphometric analyses of trapezia. The broader range of application, larger field of view, and shorter acquisition time make CBCT a valuable alternative to HR-pQCT. © 2019 American Society for Bone and Mineral Research.

Cone-beam computed tomography compared to X-ray in diagnosis of extremities bone fractures: A study of 198 cases

CBCT is an imaging technique consisting of X-ray computed tomography, in which the x-rays are divergent, forming a cone. During 2015, a new model of CBCT, New Tom 5G XL (Verona), was used in the Radiology Department of The University of Verona, in collaboration with the Orthopaedics Department. Our study was carried out from October 2015 to October 2016 (198 patients). We compared CBCT with standard x-ray in the diagnosis of foot and anke fractures (and Lisfranc lesions), tibial plateau fractures, wrist and scaphoid fractures, elbow fractures. All patients were analyzed, of which 143 were positive or had documented bone lesions, while 55 were with no fractures seen. Of the 55 negative patients, 19 were considered positive at Standard RX, thus in 34.5% of cases the X-ray Standard examination overestimated the disease (false positive cases). Similarly, of the 143 positive patients, 21 were negative at RX, resulting in 14.6% of false negatives. We can say that if compared to standard X-ray, CBCT has higher sensitivity and specificity in the proper identification and typing of these kind of lesions, with low exposition dose if compared to MDCT. The most common rx-unrecognized fractures were in small bones of carpus and tarsus.

Comparing the diagnostic performance of radiation dose-equivalent radiography, multi-detector computed tomography and cone beam computed tomography for finger fractures - A phantom study

PURPOSE

To compare the diagnostic performance and raters´confidence of radiography, radiography equivalent dose multi-detector computed tomography (RED-MDCT) and radiography equivalent dose cone beam computed tomography (RED-CBCT) for finger fractures.

METHODS

Fractures were inflicted artificially and randomly to 10 cadaveric hands of body donors. Radiography as well as RED-MDCT and RED-CBCT imaging were performed at dose settings equivalent to radiography. Images were de-identified and analyzed by three radiologists regarding finger fractures, joint involvement and confidence with their findings. Reference standard was consensus reading by two radiologists of the fracturing protocol and high-dose multi-detector computed tomography (MDCT) images. Sensitivity and specificity were calculated and compared with Cochrane´s Q and post hoc analysis. Rater´s confidence was calculated with Friedman Test and post hoc Nemenyi Test.

RESULTS

Rater´s confidence, inter-rater correlation, specificity for fractures and joint involvement were higher in RED-MDCT and RED-CBCT compared to radiography. No differences between the modalities were found regarding sensitivity.

CONCLUSION

In this phantom study, radiography equivalent dose computed tomography (RED-CT) demonstrates a partly higher diagnostic accuracy than radiography. Implementing RED-CT in the diagnostic work-up of finger fractures could improve diagnostics, support correct classification and adequate treatment. Clinical studies should be performed to confirm these preliminary results.

[Design and optimization of a cone-beam CT system for extremity imaging]

OBJECTIVE

To establish a cone beam computed tomography (ECBCT) system for high-resolution imaging of the extremities.

METHODS

Based on three-dimensional X-Ray CT imaging and high-resolution flat plate detector technique, we constructed a physical model and a geometric model for ECBCT imaging, optimized the geometric calibration and image reconstruction methods, and established the scanner system. In the experiments, the pencil vase phantom, image quality (IQ) phantom and a swine feet were scanned using this imaging system to evaluate its effectiveness and stability.

RESULTS

On the reconstructed image of the pencil vase phantom, the edges were well preserved with geometric calibrated parameters and no aliasing artifacts were observed. The reconstructed images of the IQ phantom showed a uniform distribution of the CT number, and the noise power spectra were stable in multiple scanning under the same condition. The reconstructed images of the swine feet had clearly displayed the bones with a good resolution.

CONCLUSIONS

The ECBCT system can be used for highresolution imaging of the extremities to provide important imaging information to assist in the diagnosis of bone diseases.

Quantification of bone microstructure in the wrist using cone-beam computed tomography

Due to the rising life expectancy, bone diseases (e.g. osteoporosis, osteoarthritis) and trauma (e.g. fracture) have become an important socio-economic burden. Accurate visualization and quantification of the bone microstructure in vivo is seen as an important step to enhance diagnosis and treatment. Micro-computed tomography (microCT) has become the gold standard in three-dimensional (3D) imaging of trabecular bone structure. Yet, usage is limited to ex vivo analyses, hence, it cannot be used to evaluate bone and bone adaptive responses in a patient. High-resolution peripheral computed tomography (HR-pQCT) is considered the best technique to measure the bone microarchitecture in vivo. By design HR-pQCT is limited to scanning extremities, such as the distal radius and distal tibia with a limited field of view and long scanning time (~2 à 3 min. for a stack of 0.9 cm). Cone-beam computed tomography (CBCT) is a promising alternative with a much larger field of view. Yet, CBCT is challenged by artefacts that reduce image contrast, such that it is currently being used for qualitative evaluation only. Therefore, the aims of this work were first to enhance image contrast and second to determine the accuracy of high-resolution CBCT for bone microarchitectural assessment. Trapezia of nineteen female arthritic patients were scanned twice ex vivo; once using CBCT (NewTom 5G, Cefla, Verona, Italy) at a nominal voxel size of 75 μm and once using microCT (SkyScan 1172, Bruker, Kontich, Belgium) at a voxel size of 19.84 μm. The CBCT-scans were reconstructed following 2 protocols: (1) using the commercial software delivered with the scanner and (2) using in-house developed software. After reconstruction and image processing, the images were segmented using adaptive thresholding. Bone morphometric parameters including bone volume (BV), total tissue volume (TV), bone volume fraction (BV/TV), bone surface density (BS/TV), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp) and trabecular number (Tb.N) were calculated. Statistical evaluations were made at a significance level of 5%. Significant correlations were found between the CBCT-based bone parameters and the microCT-based parameters with R² > 0.68 The in-house reconstructed software outperformed the commercial software. Smaller bias (overestimation of Tb.Th decreased from 114.24% to 59.96%) as well as higher correlations were observed for the in-house processed images. Still, a significant overestimation was observed for BV/TV and Tb. Th and an underestimation for Tb.N. We conclude that our CBCT image reconstruction improved image contrast which allowed for an accurate quantification of trabecular bone microarchitecture.

Morphofunctional evaluation of buccopharyngeal space using three-dimensional cone-beam computed tomography (3D-CBCT)

The present study aims to identify the anatomical functional changes of the buccopharyngeal space in case of singers with canto voice. The interest in this field is particularly important in view of the relation between the artistic performance level, phoniatry and functional anatomy, as the voice formation mechanism is not completely known yet. We conducted a morphometric study on three soprano voices that differ in type and training level. The anatomical soft structures from the superior vocal formant of each soprano were measured on images captured using the Cone-beam Computed Tomography (CBCT) technique. The results obtained, as well as the 3D reconstructions emphasize the particularities of the individual morphological features, especially in case of the experienced soprano soloist, which are found to be different for each anatomical soft structure, as well as for their integrity. The experimental results are encouraging and suggest further development of this study on soprano voices and also on other types of opera voices.

Comparison of the diagnostic accuracy of cone beam computed tomography and radiography for scaphoid fractures

The aim of this study was to evaluate and compare the diagnostic accuracy, the inter-rater agreement and raters’ certainty of cone beam computed tomography (CBCT) and radiography for the detection of scaphoid fractures. Our hypothesis is that the CBCT has a higher diagnostic accuracy for scaphoid fractures than radiography. We retrospectively analysed patients who underwent both radiography and CBCT examinations within 4 days to rule out a scaphoid fracture over a 2-year period in our institution. 4 blinded radiologists and orthopaedic surgeons independently rated the images regarding the presence of a scaphoid fracture. The reference standard was evaluated by two radiologists in a consensus reading. Inter-rater correlation was evaluated, pooled sensitivity, specificity, positive and negative predictive values were calculated and compared. 102 patients met the inclusion criteria. 52% of them had a scaphoid fracture. The inter-rater correlation was higher in the CBCT compared to radiography (P < 0.001). Sensitivity, specificity, positive and negative predictive values were higher for CBCT than for radiography (P < 0.019). Observers’ fracture classifications showed a higher correlation with the reference standard in the CBCT. Observers’ certainty for fracture detection and classification were higher in the CBCT. CBCT shows a higher diagnostic accuracy for scaphoid fractures than radiography.

Effect of patient anxiety on image motion artefacts in CBCT

BACKGROUND

Artefacts in images related to patient movement decrease image quality, potentially necessitating re-scanning, which leads to an extra radiation dose for the patient. Thus, avoiding patient motion reduces patient exposure to radiation. The aim of this study was to analyse image motion artefacts (MAs) and how they are affected by patient anxiety during cone beam computed tomography (CBCT) examination.

METHODS

A total of 100 patients undergoing CBCT examination were investigated. The State Trait Anxiety Inventory (STAI-S and STAI-T) form was used to measure patient anxiety. Patient's age, gender, dental anxiety score, diagnostic reason for CBCT examination, field of view (FOV), acquisition time, anatomical area, and presence of motion artefacts on images were recorded. Comparisons of the parameters were evaluated using Pearson's correlation, the chi-square test, the Mann-Whitney U test, the Kruskal-Wallis test and t-tests. The significance level was set at 0.05.

RESULTS

The mean values of the scores for the total population were 37.2 for the STAI-S and 41.6 for the STAI-T. Women exhibited higher anxiety levels than men. The patients' anxiety scores were significantly correlated with dental fear. The prevalence of patients showing motion artefacts was 6%. The mean age of patients with motion artefacts on their images (56.83) was higher than that of patients without (39.14). There was no relationship between motion artefact presence and patient gender, anxiety score, diagnostic reason for CBCT examination, FOV, acquisition time, or anatomical area. Patients showing motion artefacts on their images had higher STAI scores than those with no motion artefacts (non-significant).

CONCLUSIONS

The population in this study experienced anxiety before CBCT scanning. Excessive anxiety did not clearly affect whether image motion artefacts were generated during CBCT examination, although a non-significant increase in STAI scores was noticed in patients with motion artefacts on their images.

Comparison of Diagnostic Accuracy of Radiation Dose-Equivalent Radiography, Multidetector Computed Tomography and Cone Beam Computed Tomography for Fractures of Adult Cadaveric Wrists

PURPOSE

To compare the diagnostic accuracy of radiography, to radiography equivalent dose multidetector computed tomography (RED-MDCT) and to radiography equivalent dose cone beam computed tomography (RED-CBCT) for wrist fractures.

METHODS

As study subjects we obtained 10 cadaveric human hands from body donors. Distal radius, distal ulna and carpal bones (n = 100) were artificially fractured in random order in a controlled experimental setting. We performed radiation dose equivalent radiography (settings as in standard clinical care), RED-MDCT in a 320 row MDCT with single shot mode and RED-CBCT in a device dedicated to musculoskeletal imaging. Three raters independently evaluated the resulting images for fractures and the level of confidence for each finding. Gold standard was evaluated by consensus reading of a high-dose MDCT.

RESULTS

Pooled sensitivity was higher in RED-MDCT with 0.89 and RED-MDCT with 0.81 compared to radiography with 0.54 (P = < .004). No significant differences were detected concerning the modalities' specificities (with values between P = .98). Raters' confidence was higher in RED-MDCT and RED-CBCT compared to radiography (P < .001).

CONCLUSION

The diagnostic accuracy of RED-MDCT and RED-CBCT for wrist fractures proved to be similar and in some parts even higher compared to radiography. Readers are more confident in their reporting with the cross sectional modalities. Dose equivalent cross sectional computed tomography of the wrist could replace plain radiography for fracture diagnosis in the long run.

Clinical cone beam computed tomography compared to high-resolution peripheral computed tomography in the assessment of distal radius bone

Clinical cone beam computed tomography (CBCT) was compared to high-resolution peripheral quantitative computed tomography (HR-pQCT) for the assessment of ex vivo radii. Strong correlations were found for geometry, volumetric density, and trabecular structure. Using CBCT, bone architecture assessment was feasible but compared to HR-pQCT, trabecular parameters were overestimated whereas cortical ones were underestimated.

INTRODUCTION

HR-pQCT is the most widely used technique to assess bone microarchitecture in vivo. Yet, this technology has been only applicable at peripheral sites, in only few research centers. Clinical CBCT is more widely available but quantitative assessment of the bone structure is usually not performed. We aimed to compare the assessment of bone structure with CBCT (NewTom 5G, QR, Verona, Italy) and HR-pQCT (XtremeCT, Scanco Medical AG, Brüttisellen, Switzerland).

METHODS

Twenty-four distal radius specimens were scanned with these two devices with a reconstructed voxel size of 75 μm for Newtom 5G and 82 μm for XtremeCT, respectively. A rescaling-registration scheme was used to define the common volume of interest. Cortical and trabecular compartments were separated using a semiautomated double contouring method. Density and microstructure were assessed with the HR-pQCT software on both modality images.

RESULTS

Strong correlations were found for geometry parameters (r = 0.98-0.99), volumetric density (r = 0.91-0.99), and trabecular structure (r = 0.94-0.99), all p < 0.001. Correlations were lower for cortical microstructure (r = 0.80-0.89), p < 0.001. However, absolute differences were observed between modalities for all parameters, with an overestimation of the trabecular structure (trabecular number, 1.62 ± 0.37 vs. 1.47 ± 0.36 mm(-1)) and an underestimation of the cortical microstructure (cortical porosity, 3.3 ± 1.3 vs. 4.4 ± 1.4 %) assessed on CBCT images compared to HR-pQCT images.

CONCLUSIONS

Clinical CBCT devices are able to analyze large portions of distal bones with good spatial resolution and limited irradiation. However, compared to dedicated HR-pQCT, the assessment of microarchitecture by NewTom 5G dental CBCT showed some discrepancies, for density measurements mainly. Further technical developments are required to reach optimal assessment of bone characteristics.

Predicting Trabecular Bone Stiffness from Clinical Cone-Beam CT and HR-pQCT Data; an In Vitro Study Using Finite Element Analysis

Stiffness and shear moduli of human trabecular bone may be analyzed in vivo by finite element (FE) analysis from image data obtained by clinical imaging equipment such as high resolution peripheral quantitative computed tomography (HR-pQCT). In clinical practice today, this is done in the peripheral skeleton like the wrist and heel. In this cadaveric bone study, fourteen bone specimens from the wrist were imaged by two dental cone beam computed tomography (CBCT) devices and one HR-pQCT device as well as by dual energy X-ray absorptiometry (DXA). Histomorphometric measurements from micro-CT data were used as gold standard. The image processing was done with an in-house developed code based on the automated region growing (ARG) algorithm. Evaluation of how well stiffness (Young's modulus E3) and minimum shear modulus from the 12, 13, or 23 could be predicted from the CBCT and HR-pQCT imaging data was studied and compared to FE analysis from the micro-CT imaging data. Strong correlations were found between the clinical machines and micro-CT regarding trabecular bone structure parameters, such as bone volume over total volume, trabecular thickness, trabecular number and trabecular nodes (varying from 0.79 to 0.96). The two CBCT devices as well as the HR-pQCT showed the ability to predict stiffness and shear, with adjusted R2-values between 0.78 and 0.92, based on data derived through our in-house developed code based on the ARG algorithm. These findings indicate that clinically used CBCT may be a feasible method for clinical studies of bone structure and mechanical properties in future osteoporosis research.

Initial Clinical Experience With Extremity Cone-Beam CT of the Foot and Ankle in Pediatric Patients

OBJECTIVE

Extremity cone-beam CT (CBCT) scanners have become available for clinical use in the United States. The purpose of this study was to review an initial clinical experience with CBCT of the foot and ankle in pediatric patients.

MATERIALS AND METHODS

A retrospective review was conducted of all foot or ankle CBCT examinations performed on patients 18 years old and younger at one institution from August 1, 2013, through February 28, 2015. A t test was used to compare mean effective dose for CBCT with that for MDCT foot or ankle examinations of age-matched control subjects. To assess changes in utilization, a t test also was used to compare the mean numbers of foot or ankle CT examinations per month before and after installation of the CBCT scanner at the institution.

RESULTS

Thirty-four CBCT examinations were performed. The mean effective dose was 0.013 ± 0.003 mSv compared with 0.023 ± 0.020 mSv for MDCT of age-matched control subjects (p < 0.005). The mean numbers of foot or ankle CT examinations per month were 3.4 in the 18 months before and 3.8 in the 18 months after installation of the CBCT scanner (p = 0.28). The mean number of foot or ankle MDCT examinations per month decreased significantly (3.4 vs 1.9, p = 0.03) over the same period. In 56% of patients, CBCT revealed important findings that were not visible on contemporaneous radiographs. In 68% of patients, the CBCT findings affected clinical management.

CONCLUSION

CBCT of the foot or ankle of pediatric patients is a viable lower-dose alternative to MDCT that provides important information that may affect clinical management.

A retrospective, semi-quantitative image quality analysis of cone beam computed tomography (CBCT) and MSCT in the diagnosis of distal radius fractures

OBJECTIVE

To compare image quality and diagnostic validity of CBCT and MSCT for distal radius fractures.

METHODS

35 CBCT and 33 MSCT scans were retrospectively reviewed with a visual grading scale regarding the depiction of cortical bone, trabecular bone, articular surfaces, and soft tissue. The extent and type of artefacts was analyzed. Agreement on AO classification and measurement of cortical disruption and length of the fracture gap was determined. Fracture reduction was evaluated in post-treatment x-rays. Statistical analysis was performed with visual grading characteristics (VGC), chi square tests, and Kendall's coefficient of concordance.

RESULTS

CBCT performed significantly worse for cortical bone, articular surfaces, and especially soft tissue. Trabecular bone showed no significant difference. Significantly more CBCT images showed artefacts. Physics-based artefacts were the most common. CBCT scans also showed motion artefacts. There was no significant difference in agreement on AO classification. The agreement on measurements was substantial for both modalities. Slightly more fractures that had undergone MSCT imaging showed adequate reduction.

CONCLUSION

This initial study of an orthopaedic extremity CBCT scanner showed that the image quality of a CBCT scanner remains inferior for most structures at standard settings. Diagnostic validity of both modalities for distal radius fractures seems similar.

KEY POINTS

• Subjectively, CBCT remains inferior to MSCT in depicting most structures. • Similar diagnostic validity for CBCT and MSCT imaging of distal radius fractures. • CBCT is a possible alternative to MSCT in musculoskeletal imaging. • Visual grading characteristics (VGC) analysis proves useful in analyzing visual grading scales.

Initial Report on the Use of In-Office Cone Beam Computed Tomography for Early Diagnosis of Osteomyelitis in Diabetic Patients

Osteomyelitis is one of the most feared sequelae of diabetic foot ulceration, which often leads to lower-extremity amputation and disability. Early diagnosis of osteomyelitis increases the likelihood of successful treatment and may limit the amount of bone resected, preserving ambulatory function. Although a variety of techniques exist for imaging the diabetic foot, standard radiography is still the only in-office imaging modality used today. However, radiographs lack sensitivity and specificity, making it difficult to diagnose bone infection at its early stages. In this report, we describe our initial experience with a cone beam computed tomography (CBCT)-based device, which may serve as an accurate and readily available tool for early diagnosis of osteomyelitis in a patient with diabetes. Two patients with infected diabetic foot ulcers were evaluated for osteomyelitis using radiography and CBCT. Positive imaging findings were confirmed by bone biopsy. In both patients, CBCT captured early osteolytic changes that were not apparent on radiographs, leading to early surgical intervention and successful treatment. The CBCT was helpful in facilitating detection and early clinical intervention for osteomyelitis in two diabetic patients with foot ulcers. These results are encouraging and warrant future evaluation.

Cone-Beam CT in diagnosis of scaphoid fractures

OBJECTIVE

This prospective study investigated the sensitivity of cone beam computed tomography (CBCT), a low dose technique recently made available for extremity examinations, in detecting scaphoid fractures. Magnetic resonance imaging (MRI) was used as gold standard for scaphoid fractures.

MATERIALS AND METHODS

A total of 95 patients with a clinically suspected scaphoid fracture were examined with radiography and CBCT in the acute setting. A negative CBCT exam was followed by an MRI within 2 weeks. When a scaphoid fracture was detected on MRI a new CBCT was performed.

RESULTS

Radiography depicted seven scaphoid fractures, all of which were also seen with CBCT. CBCT detected another four scaphoid fractures. With MRI another five scaphoid fractures were identified that were not seen with radiography or with CBCT. These were also not visible on the reexamination CBCT. Sensitivity for radiography was 44, 95 % confidence interval 21-69 %, and for CBCT 69 %, 95 % confidence interval 41-88 % (p = 0.12). Several non-scaphoid fractures in the carpal region were identified, radiography and CBCT depicted 7 and 34, respectively (p < 0.0001).

CONCLUSION

CBCT is a superior alternative to radiography, entailing more accurate diagnoses of carpal region fractures, and thereby requiring fewer follow-up MRI examinations. However, CBCT cannot be used to exclude scaphoid fractures, since MRI identified additional occult scaphoid fractures.

Direct comparison of conventional radiography and cone-beam CT in small bone and joint trauma

OBJECTIVE

To compare the diagnostic value of cone-beam computed tomography (CBCT) and conventional radiography (CR) after acute small bone or joint trauma.

MATERIALS AND METHODS

Between March 2013 and January 2014, 231 patients with recent small bone or joint trauma underwent CR and subsequent CBCT. CR and CBCT examinations were independently assessed by two readers, blinded to the result of the other modality. The total number of fractures as well as the number of complex fractures were compared, and inter- and intraobserver agreement for CBCT was calculated. In addition, radiation doses and evaluation times for both modalities were noted and statistically compared.

RESULTS

Fracture detection on CBCT increased by 35% and 37% for reader 1 and reader 2, respectively, and identification of complex fractures increased by 236% and 185%. Interobserver agreement for CBCT was almost perfect, as was intraobserver agreement for reader 1. The intraobserver agreement for reader 2 was substantial. Radiation doses and evaluation time were significantly higher for CBCT.

CONCLUSION

CBCT detects significantly more small bone and joint fractures, in particular complex fractures, than CR. In the majority of cases, the clinical implication of the additionally detected fractures is limited, but in some patients (e.g., fracture-dislocations), the management is significantly influenced by these findings. As the radiation dose for CBCT substantially exceeds that of CR, we suggest adhering to CR as the first-line examination after small bone and joint trauma and keeping CBCT for patients with clinical-radiographic discordance or suspected complex fractures in need of further (preoperative) assessment.

Comparison of Multidetector Computed Tomography and Flat-Panel Computed Tomography Regarding Visualization of Cortical Fractures, Cortical Defects, and Orthopedic Screws: A Phantom Study

To compare the visualization of cortical fractures, cortical defects, and orthopedic screws in a dedicated extremity flat-panel computed tomography (FPCT) scanner and a multidetector computed tomography (MDCT) scanner.We used feet of European roe deer as phantoms for cortical fractures, cortical defects, and implanted orthopedic screws. FPCT and MDCT scans were performed with equivalent dose settings. Six observers rated the scans according to number of fragments, size of defects, size of defects opposite orthopedic screws, and the length of different screws. The image quality regarding depiction of the cortical bone was assessed. The gold standard (real number of fragments) was evaluated by autopsy.The correlation of reader assessment of fragments, cortical defects, and screws with the gold standard was similar for FPCT and MDCT. Three readers rated the subjective image quality of the MDCT to be higher, whereas the others showed no preferences.Although the image quality was rated higher in the MDCT than in the FPCT by 3 out of 6 observers, both modalities proved to be comparable regarding the visualization of cortical fractures, cortical defects, and orthopedic screws and of use to musculoskeletal radiology regarding fracture detection and postsurgical evaluation in our experimental setting.

Using cone-beam CT as a low-dose 3D imaging technique for the extremities: initial experience in 50 subjects

PURPOSE

To prospectively evaluate a dedicated extremity cone-beam CT (CBCT) scanner in cases with and without orthopedic hardware by (1) comparing its imaging duration and image quality to those of radiography and multidetector CT (MDCT) and (2) comparing its radiation dose to that of MDCT.

MATERIALS AND METHODS

Written informed consent was obtained for all subjects for this IRB-approved, HIPAA-compliant study. Fifty subjects with (1) fracture of small bones, (2) suspected intraarticular fracture, (3) fracture at the site of complex anatomy, or (4) a surgical site difficult to assess with radiography alone were recruited and scanned on an extremity CBCT scanner prior to FDA approval. Same-day radiographs were performed in all subjects. Some subjects also underwent MDCT within 1 month of CBCT. Imaging duration and image quality were compared between CBCT and radiographs. Imaging duration, effective radiation dose, and image quality were compared between CBCT and MDCT.

RESULTS

Fifty-one CBCT scans were performed in 50 subjects. Average imaging duration was shorter for CBCT than radiographs (4.5 min vs. 6.6 min, P = 0.001, n = 51) and MDCT (7.6 min vs. 10.9 min, P = 0.01, n = 7). Average estimated effective radiation dose was less for CBCT than MDCT (0.04 mSv vs. 0.13 mSv, P =  .02, n = 7). CBCT images yielded more diagnostic information than radiographs in 23/51 cases and more diagnostic information than MDCT in 1/7 cases, although radiographs were superior for detecting hardware complications.

CONCLUSION

CBCT performs high-resolution imaging of the extremities using less imaging time than radiographs and MDCT and lower radiation dose than MDCT.

Reduction of radiation exposure by lead curtain shielding in dedicated extremity cone beam CT

OBJECTIVE

A dedicated extremity cone beam CT (CBCT) was introduced recently, and is rapidly becoming an attractive modality for extremity imaging. This study aimed to evaluate the effectiveness of a curtain-shaped lead shielding in reducing the exposure of patients to scattered radiation in dedicated extremity CBCT.

METHODS

A dedicated extremity CBCT scanner was used. The lead shielding curtain was 42 × 60 cm with 0.5-mm lead equivalent. Scattered radiation dose from CBCT was measured using thermoluminescence dosimetry chips at 20 points, at different distances and directions from the CT gantry. Two sets of scattered radiation dose measurements were performed before and after installation of curtain-shaped lead shield, and the percentage reduction in dose in air was calculated.

RESULTS

Mean radiation exposure dose at measured points was 34.46 ± 48.40 μGy without curtains and 9.67 ± 4.53 μGy with curtains, exhibiting 71.94% reduction (p = 0.000). The use of lead shielding curtains significantly reduced scattered radiation at 0.5, 1.0 and 1.5 m from the CT gantry, with percent reductions of 84.8%, 58.0% and 35.5%, respectively (p = 0.000, 0.000 and 0.002). The percent reduction in the diagonal (+45°, -45°) and vertical forward (0°) directions were 86.3%, 83.1% and 77.7%, respectively, and were statistically significant (p = 0.029, 0.020 and 0.041).

CONCLUSION

Shielding with lead curtains suggests an easy and effective method for reducing patient exposure to radiation in extremity CBCT imaging.

ADVANCES IN KNOWLEDGE

Lead shielding curtains are an effective technique to reduce scattered radiation dose in dedicated extremity CBCT, with higher dose reduction closer to the gantry opening.

A comparative study for image quality and radiation dose of a cone beam computed tomography scanner and a multislice computed tomography scanner for paranasal sinus imaging

OBJECTIVES

To evaluate image quality and radiation dose of a state of the art cone beam computed tomography (CBCT) system and a multislice computed tomography (MSCT) system in patients with sinonasal poliposis.

METHODS

In this retrospective study two radiologists evaluated 57 patients with sinonasal poliposis who underwent a CBCT or MSCT sinus examination, along with a control group of 90 patients with normal radiological findings. Tissue doses were measured using a phantom model with thermoluminescent dosimeters (TLD).

RESULTS

Overall image quality in CBCT was scored significantly higher than in MSCT in patients with normal radiologic findings (p-value: 0.00001). In patients with sinonasal poliposis, MSCT scored significantly higher than CBCT (p-value: 0.00001). The average effective dose for MSCT was 42% higher compared to CBCT (108 μSv vs 63 μSv).

CONCLUSIONS

CBCT and MSCT are both suited for the evaluation of sinonasal poliposis. In patients with sinonasal poliposis, clinically important structures of the paranasal sinuses can be better delineated with MSCT, whereas in patients without sinonasal poliposis, CBCT turns out to define the important structures of the sinonasal region better. However, given the lower radiation dose, CBCT can be considered for the evaluation of the sinonasal structures in patients with sinonasal poliposis.

KEY POINTS

• CBCT and MSCT are both suited for evaluation of sinonasal poliposis. • Effective dose for MSCT was 42% higher compared to CBCT. • In patients with sinonasal poliposis, clinically important anatomical structures are better delineated with MSCT. • In patients with normal radiological findings, clinically important anatomical structures are better delineated with CBCT.

Radiation dose reduction in cone-beam computed tomography of extremities: evaluation of a novel radiation shield

Cone-beam computed tomography (CBCT) is a relatively new technique for imaging of extremities. It provides high-resolution images with lower effective dose compared to conventional CT. However following the ALARA principle, CBCT-imaging protocols and practices must also be optimised to minimize the dose absorbed by the patient as well as personnel. The aim of this study is to evaluate the effect of a novel scanner-attached radiation shield on the dose absorbed by the patient and on the amount of scattered radiation around the scanner.An orthopedic CBCT scanner was applied for comparing the doses with and without the shield during an elbow and a knee scan. A homogeneous 8 cm PMMA phantom with either an anthropomorphic Alderson phantom or a 16 cm PMMA phantom simulated the tissues of a patient. Measurements were made for several scan parameters using calibrated dose meters.The results show that the radiation shield significantly decreased the doses measured on the patient during CBCT scans of the elbow and the knee. The usage of the shield decreased the absorbed doses by up to 95.5%. Also scattered radiation around the gantry decreased notably. The use of the shield is highly recommended, especially for pediatric patients.

Trabecular bone structure parameters from 3D image processing of clinical multi-slice and cone-beam computed tomography data

OBJECTIVE

Bone strength depends on both mineral content and bone structure. The aim of this in vitro study was to develop a method of quantitatively assessing trabecular bone structure by applying three-dimensional image processing to data acquired with multi-slice and cone-beam computed tomography using micro-computed tomography as a reference.

MATERIALS AND METHODS

Fifteen bone samples from the radius were examined. After segmentation, quantitative measures of bone volume, trabecular thickness, trabecular separation, trabecular number, trabecular nodes, and trabecular termini were obtained.

RESULTS

The clinical machines overestimated bone volume and trabecular thickness and underestimated trabecular nodes and number, but cone-beam CT to a lesser extent. Parameters obtained from cone beam CT were strongly correlated with μCT, with correlation coefficients between 0.93 and 0.98 for all parameters except trabecular termini.

CONCLUSIONS

The high correlation between cone-beam CT and micro-CT suggest the possibility of quantifying and monitoring changes of trabecular bone microarchitecture in vivo using cone beam CT.

Cone beam CT: a current overview of devices

The purpose of this study was to review and compare the properties of all the available cone beam CT (CBCT) devices offered on the market, while focusing especially on Europe. In this study, we included all the different commonly used CBCT devices currently available on the European market. Information about the properties of each device was obtained from the manufacturers' official available data, which was later confirmed by their representatives in cases where it was necessary. The main features of a total of 47 CBCT devices that are currently marketed by 20 companies were presented, compared and discussed in this study. All these CBCT devices differ in specific properties according to the companies that produce them. The summarized technical data from a large number of CBCT devices currently on the market offer a wide range of imaging possibilities in the oral and maxillofacial region.

CT arthrography of the wrist using a novel, mobile, dedicated extremity cone-beam CT (CBCT)

PURPOSE

To evaluate the feasibility and intra- and interobserver agreement of CBCT arthrography of wrist ligaments, triangular fibrocartilaginous complex (TFCC), and to assess the sensitivity (SE), specificity (SP), accuracy (ACC), and positive and negative predictive value (PPV, NPV) of CBCT arthrography in the diagnosis of scapholunate (SLL) and lunotriquetral (LTL) ligament tears, TFCC, and cartilage abnormalities of the scaphoid and lunate with their corresponding radial surfaces (scaphoid and lunate fossa) using a novel, mobile, dedicated extremity CBCT scanner.

MATERIALS AND METHODS

Fifty-two consecutively enrolled subjects (26 M, 26 F, mean age 38 years, range 18-66 years) with suspected wrist ligament tears underwent CBCT-arthrography before normally scheduled MR arthrography.An extremity CBCT was used for imaging with isotropic voxel size of 0.4 × 0.4 × 0.4 mm(3). Subsequent routine 1.5 T MRI was performed using a dedicated wrist coil.Two observers reviewed the anonymized CBCT images twice for contrast enhancement (CE) and technical details (TD), for tears of the SLL, LTL, and TFCC. Also, cartilage abnormalities of the scaphoid and lunate with their corresponding radial surfaces (scaphoid and lunate fossa) were evaluated. Inter- and intraobserver agreement was determined using weighted kappa statistics. Since no surgery was performed, MRI served as a reference standard, and SE and SP, ACC, PPV, and NPV were calculated.

RESULTS

Intra- and interobserver kappa values for both readers (reader 1/reader 2; first reading/second reading) with 95 % confidence limits were: CE 0.54 (0.08-1.00)/ 0.75 (0.46-1.00); 0.73 (0.29-1.00)/ 0.45 (0.07-0.83), TD 0.53 (0.30-0.88)/ 0.86 (0.60-1.00); 0.56 (0.22-0.91)/ 0.67 (0.37-0.98), SLL 0.59 (0.25-0.93)/ 0.66 (0.42-0.91); 0.31 (0.06-0.56)/ 0.49 (0.26-0.73), LTL 0.83 (0.66-1.00)/ 0.68 (0.46-0.91); 0.90 (0.79-1.00)/ 0.48 (0.22-0.74); TFCC (0.72-1.00)/ (0.79-1.00); 0.65 (0.43-0.87)/ 0.59 (0.35-0.83), radius (scaphoid fossa) 0.45 (0.12-0.77)/ 0.64 (0.31-0.96); 0.58 (0.19-0.96)/ 0.38 (0.09-0.66), scaphoid 0.43 (0.12-0.74)/ 0.76 (0.55-0.96); 0.37 (0.00-0.75)/ 0.32 (0.04-0.59), radius (lunate fossa) 0.68 (0.36-1.00)/ 0.42 (0.00-0.86); 0.62 (0.29-0.96)/ 0.51 (0.12-0.91), and lunate 0.53 (0.16-0.90)/ 0.68 (0.44-0.91); 0.59 (0.29-0.88)/ 0.42 (0.00-0.84), respectively. The overall mean accuracy was 82-92 % and specificity was 81-94 %. Sensitivity for LTL and TFCC tears was 76-83, but for SLL tears it was 58 %. For cartilage abnormalities, the accuracy and negative predictive value were high, 90-98 %.

CONCLUSIONS

A dedicated CBCT extremity scanner is a new method for evaluating the wrist ligaments and radiocarpal cartilage. The method has an overall accuracy of 82-86 % and specificity 81-91 %. For cartilage abnormalities, the accuracy and negative predictive value were high.

C-arm flat-panel CT arthrography of the wrist and elbow: first experiences in human cadavers

OBJECTIVE

To determine the optimal intra-articular iodine concentration for C-arm flat-panel computed tomography (FPCT) arthrography using advanced joint phantoms and to evaluate its application in human cadaveric wrists and elbows. Multi-detector (MD) CT served as the standard of reference.

MATERIALS AND METHODS

Joint phantoms and 10 human cadaveric wrist and elbow joints were scanned with C-arm FPCT (5-s, 8-s, and 20-s runs) and standard MDCT using different and optimal concentrations of iodinated contrast material. CT numbers of contrast material, tissue, and noise were measured and contrast-to-noise ratios (CNR) calculated for quantitative analysis. Image and depiction of cartilage, bone, and soft tissues were rated. Radiation doses were compared.

RESULTS

In FPCT, iodine concentrations positively correlated with CT numbers and noise of contrast material and with radiation dose (r = 0.713-0.996, p < 0.05 each). At an iodine concentration of 45 mg/ml, CNR of cartilage and soft tissues were highest for all FPCT acquisitions and higher than in MDCT. The 20-s FPCT run performed best for image quality and depiction of anatomical structures and was rated overall equal to MDCT (p = 0.857).

CONCLUSION

The optimal iodine concentration for C-arm FPCT arthrography in this study is 45 mg/ml, leading to superior CNR and image quality for an optimal FPCT protocol compared with standard MDCT arthrography in human cadaveric joints.

Technical assessment of a cone-beam CT scanner for otolaryngology imaging: image quality, dose, and technique protocols

PURPOSE

As cone-beam CT (CBCT) systems dedicated to various imaging specialties proliferate, technical assessment grounded in imaging physics is important to ensuring that image quality and radiation dose are quantified, understood, and justified. This paper involves technical assessment of a new CBCT scanner (CS 9300, Carestream Health, Rochester, NY) dedicated to imaging of the ear and sinuses for applications in otolaryngology-head and neck surgery (OHNS). The results guided evaluation of technique protocols to minimize radiation dose in a manner sufficient for OHNS imaging tasks.

METHODS

The technical assessment focused on the imaging performance and radiation dose for each of seven technique protocols recommended by the manufacturer: three sinus protocols and four ear (temporal bone) protocols. Absolute dose was measured using techniques adapted from AAPM Task Group Report No. 111, involving three stacked 16 cm diameter acrylic cylinders (CTDI phantoms) and a 0.6 cm(3) Farmer ionization chamber to measure central and peripheral dose. The central dose (D(o)) was also measured as a function of longitudinal position (z) within and beyond the primary radiation field to assess, for example, out-of-field dose to the neck. Signal-difference-to-noise ratio (SDNR) and Hounsfield unit (HU) accuracy were assessed in a commercially available quality assurance phantom (CATPHAN module CTP404, The Phantom Laboratory, Greenwich, NY) and a custom phantom with soft-tissue-simulating plastic inserts (Gammex RMI, Madison, WI). Spatial resolution was assessed both qualitatively (a line-pair pattern, CATPHAN module CTP528) and quantitatively (modulation transfer function, MTF, measured with a wire phantom). Imaging performance pertinent to various OHNS imaging tasks was qualitatively assessed using an anthropomorphic phantom as evaluated by two experienced OHNS specialists.

RESULTS

The technical assessment motivated a variety of modifications to the manufacturer-specified protocols to provide reduced radiation dose without compromising pertinent task-based imaging performance. The revised protocols yielded D(o) ranging 2.9-5.7 mGy, representing a ∼30% reduction in dose from the original technique chart. Out-of-field dose was ∼10% of D(o) at a distance of ∼8 cm from the field edge. Soft-tissue contrast resolution was fairly limited (water-brain SDNR ∼0.4-0.7) while high-contrast performance was reasonably good (SDNR ∼2-4 for a polystyrene insert in the CATPHAN). The scanner does not demonstrate (or claim to provide) accurate HU and exhibits a systematic error in CT number that could potentially be addressed by further calibration. The spatial resolution is ∼10-16 lp∕cm as assessed in a line-pair phantom, with MTF exceeding 10% out to ∼20 lp∕cm. Qualitative assessment by expert readers suggested limited soft-tissue visibility but excellent high-contrast (bone) visualization with isotropic spatial resolution suitable to a broad spectrum of pertinent sinus and temporal bone imaging tasks.

CONCLUSIONS

The CBCT scanner provided spatial and contrast resolution suitable to visualization of high-contrast morphology in sinus, maxillofacial, and otologic imaging applications. Rigorous technical assessment guided revision of technique protocols to reduce radiation dose while maintaining image quality sufficient for pertinent imaging tasks. The scanner appears well suited to high-contrast sinus and temporal bone imaging at doses comparable to or less than that reported for conventional diagnostic CT of the head.

Cone-beam computed tomography arthrography: an innovative modality for the evaluation of wrist ligament and cartilage injuries

PURPOSE

Cone-beam computed tomography (CBCT) has become an important modality in dento-facial imaging but remains poorly used in the exploration of the musculoskeletal system. The purpose of this study was to prospectively evaluate the performance and radiation exposure of CBCT arthrography in the evaluation of ligament and cartilage injuries in cadaveric wrists, with gross pathology findings as the standard of reference.

MATERIALS AND METHODS

Conventional arthrography was performed under fluoroscopic guidance on 10 cadaveric wrists, followed by MDCT acquisition and CBCT acquisition. CBCT arthrography and MDCT arthrography images were independently analyzed by two musculoskeletal radiologists working independently and then in consensus. The following items were observed: scapholunate and lunotriquetral ligaments, triangular fibrocartilage complex (TFCC) (tear, integrity), and proximal carpal row cartilage (chondral tears). Wrists were dissected and served as the standard of reference for comparisons. Interobserver agreement, sensitivity, specificity, and accuracy were determined. Radiation dose (CTDI) of both modalities was recorded.

RESULTS

CBCT arthrography provides equivalent results to MDCT arthrography in the evaluation of ligaments and cartilage with sensitivity and specificity between 82 and 100%, and interobserver agreement between 0.83 and 0.97. However, radiation dose was significantly lower (p < 0.05) for CBCT arthrography than for MDCT arthrography with a mean CTDI of 2.1 mGy (range 1.7-2.2) versus a mean of 15.1 mGy (range 14.7-16.1).

CONCLUSION

CBCT arthrography appears to be an innovative alternative to MDCT arthrography of the wrist as it allows an accurate and low radiation dose evaluation of ligaments and cartilage.