Calculus Detection Research Articles

Auxiliary Diagnosis of Dental Calculus Based on Deep Learning and Image Enhancement by Bitewing Radiographs.

In the field of dentistry, the presence of dental calculus is a commonly encountered issue. If not addressed promptly, it has the potential to lead to gum inflammation and eventual tooth loss. Bitewing (BW) images play a crucial role by providing a comprehensive visual representation of the tooth structure, allowing dentists to examine hard-to-reach areas with precision during clinical assessments. This visual aid significantly aids in the early detection of calculus, facilitating timely interventions and improving overall outcomes for patients. This study introduces a system designed for the detection of dental calculus in BW images, leveraging the power of YOLOv8 to identify individual teeth accurately. This system boasts an impressive precision rate of 97.48%, a recall (sensitivity) of 96.81%, and a specificity rate of 98.25%. Furthermore, this study introduces a novel approach to enhancing interdental edges through an advanced image-enhancement algorithm. This algorithm combines the use of a median filter and bilateral filter to refine the accuracy of convolutional neural networks in classifying dental calculus. Before image enhancement, the accuracy achieved using GoogLeNet stands at 75.00%, which significantly improves to 96.11% post-enhancement. These results hold the potential for streamlining dental consultations, enhancing the overall efficiency of dental services.

Assessment of the effectiveness of artificial intelligence-based oral screening solution in the diagnosis of dental calculus, stains, and dental caries (Logy AI oral screening solution)

Background: The objective of this study was to clinically evaluate the precision of Logy AI's oral screening solution. This innovative module, driven by artificial intelligence, operates seamlessly through WhatsApp and as a standalone smartphone application. It is designed to detect various dental issues such as stains, calculus, and caries, utilizing images captured by a smartphone camera. The accuracy of the module was assessed by comparing its diagnoses with those made by dental professionals. Methods: A prospective clinical study was conducted in Saveetha Dental College, a tertiary care hospital in the southern part of India with 325 patients. Smartphone images taken were sent to the Logy AI oral screening solution which predicted if the patient had any oral hygiene issues like stains, calculus, and caries. Patients were examined by a dentist with visual-tactile and orthopantomogram (OPG) examination and were documented. Both were compared. Results: The accuracy of the Logy AI oral screening solution for the detection of stains, calculus, and caries was comparable with the dentist's diagnosis. The accuracy was 85% for caries, 97% for stains, and 83% for calculus. The sensitivity was 88% for caries, 89% for stains, and 82% for calculus. Conclusions: The Logy AI oral screening module demonstrates potential as an efficient oral screening tool suitable for community-level deployment, particularly in remote regions lacking access to costly dental equipment and healthcare professionals. Its accuracy and efficiency make it well-suited for operation in low-resource settings. Moreover, it holds promise as a valuable home screening tool for individuals seeking to monitor their oral health proactively.

Clinical evaluation of Artificial Intelligence Driven Remote Monitoring technology for assessment of patient oral hygiene during orthodontic treatment

This study aimed to clinically evaluate the accuracy of Dental Monitoring's (DM) artificial intelligence (AI) image analysis and oral hygiene notification algorithm in identifying oral hygiene and mucogingival conditions. Twenty-four patients seeking orthodontic therapy were monitored by DM oral hygiene protocol during their orthodontic treatment. During the bonding appointment and at each of 10 subsequent adjustment visits, a total of 232 clinical oral examinations were performed to assess the presence of the 3 oral hygiene parameters that DM monitors. In each clinical timepoint, the subjects took an oral DM scan and received a notification regarding their current oral status at that moment in time. Sensitivity, specificity, positive predictive value, andnegative predictive value were calculated to evaluate AI and clinical assessment of plaque, gingivitis, and recession. A total of 232 clinical time points have been evaluated clinically and by the DM AI algorithm. For DM's AI detection of plaque and calculus, gingivitis, and recession, the sensitivity was 0.53, 0.35, and 0.22; the specificity was 0.94, 0.96, and 0.99; and the accuracy was 0.60, 0.49, and 0.72, respectively. DM's oral hygiene notification algorithm has low sensitivity, high specificity, and moderate accuracy. This indicates a tendency of DM to underreport the presence of plaque, gingivitis, and recession.

Impact of Noisy Labels on Dental Deep Learning-Calculus Detection on Bitewing Radiographs.

Supervised deep learning requires labelled data. On medical images, data is often labelled inconsistently (e.g., too large) with varying accuracies. We aimed to assess the impact of such label noise on dental calculus detection on bitewing radiographs. On 2584 bitewings calculus was accurately labeled using bounding boxes (BBs) and artificially increased and decreased stepwise, resulting in 30 consistently and 9 inconsistently noisy datasets. An object detection network (YOLOv5) was trained on each dataset and evaluated on noisy and accurate test data. Training on accurately labeled data yielded an mAP50: 0.77 (SD: 0.01). When trained on consistently too small BBs model performance significantly decreased on accurate and noisy test data. Model performance trained on consistently too large BBs decreased immediately on accurate test data (e.g., 200% BBs: mAP50: 0.24; SD: 0.05; p < 0.05), but only after drastically increasing BBs on noisy test data (e.g., 70,000%: mAP50: 0.75; SD: 0.01; p < 0.05). Models trained on inconsistent BB sizes showed a significant decrease of performance when deviating 20% or more from the original when tested on noisy data (mAP50: 0.74; SD: 0.02; p < 0.05), or 30% or more when tested on accurate data (mAP50: 0.76; SD: 0.01; p < 0.05). In conclusion, accurate predictions need accurate labeled data in the training process. Testing on noisy data may disguise the effects of noisy training data. Researchers should be aware of the relevance of accurately annotated data, especially when testing model performances.

A narrative review of imaging tools for imaging subgingival calculus.

The conventional method of detecting subgingival calculus involves using a periodontal probe to sense tactile differences on the dental root surface. Although efficient, this method can result in false positives and false negatives. This literature review explores alternative detection techniques that can detect subgingival calculus with improved accuracy and consistency. The accumulation of dental calculus below the gingival margin can foster periodontitis-inducing bacterial growth. Conventional methods of locating subgingival calculus are often inaccurate and highly dependent on clinician skill. This literature review evaluates techniques used to improve the accuracy of imaging and detecting subgingival calculus. Google Scholar, PubMed and PubMed Central databases were searched for peer-reviewed original articles evaluating subgingival calculus imaging and detection techniques. A total of 46 relevant articles ranging from 1981 to 2021 were included. This narrative review discusses the subgingival calculus detection and imaging capabilities of periodontal endoscopy in an in vivo study and of optical coherence tomography (OCT), fluorescence spectroscopy, and differential reflectometry in in vitro settings. Each technique has unique benefits and limitations that distinguishes it from the others. In vitro studies have revealed that techniques including periodontal endoscopy, OCT, fluorescence spectroscopy, or differential reflectometry allow for a more accurate diagnosis of subgingival calculus deposits in comparison to detection via periodontal probing. Despite the improved results, the common limitations of these techniques include longer operation times and expensive equipment. Further studies are needed to transition these imaging and detection methods to clinical environments.

Detection of the Renal Calculus by Twinkling Artifact in Color Doppler Ultrasonography

Introduction: Renal calculus is a solid mass of crystals that may block the urinary tract. Calcium and oxalate combine to create the majority of these crystals. These kidney stones pass via the urinary system to leave the body. Most stones may not certainly cause any symptoms or signs until they start moving toward the ureter. For detecting kidney stones twinkling artifact in Color Doppler Ultrasonography (CDU) is a useful sensitive instrument. The twinkling artifact's effect is highly dependent on machine settings and is probably created by phase (or clock) jitter. When illuminating specific rough reflecting surfaces during color Doppler imaging, this phenomenon is frequently seen. It appears as a distinct point of alternating colors that may or may not have a comet tail associated with it. Aim of the Study: The aim of the study was to detect renal calculous twinkling artifacts in color Doppler ultrasonography. Methods: This prospective clinical study was conducted at the Department of Radiology and Imaging in BIRDEM General Hospital, Dhaka, to detect the twinkling artifact in color Doppler ultrasonogram in the defection of renal calculus. The study period was one year, starting from 1st July 2013 to 30th June 2014. A total number of 59 clinically suspected subjects were selected by purposive sampling method. A consecutive selection method was followed for the selection of the participants. Result: This study was detected for the twinkling artifact in color Doppler ultrasonography. All the subjects were selected for the study by purposive sampling method. The findings derived from the data analysis are presented as tabular or figure format where necessary. Out of the total 54 patients, 35 (64.82%) were male and 19 (35.18%) were female. The mean age of the patients was (SD) ± 13.42 years their age ranged from 31 to 64 years. Diagnostic accuracy of Doppler twinkling artifact was found to be 95.83% with specificity, sensitivity, positive predictive value, ...........

Oral Health Status and Literacy/Knowledge Amongst Pregnant Women in Shanghai

BackgroundThe changes in hormones, diet, and hygiene associated with pregnancy are associated with oral diseases. There is insufficient awareness of the importance of oral health during pregnancy. This study investigated the oral health status and knowledge amongst pregnant women in Shanghai. MethodsThis cross-sectional study enrolled pregnant women at the Shanghai Red House Obstetrics & Gynecology Hospital in December 2020. The Fourth National Oral Health Questionnaire was used to evaluate the oral health status. Decayed/missing/filled teeth (DMFT) were the sum of the number of decayed, missing due to caries, and filled teeth. The chi-square test and Kruskal–Wallis test were used to compare the groups. ResultsA total of 224 pregnant women were enrolled. The rates of dental caries were 69.8%, periodontal health was 1.8%, calculus detection was 95.6%, shallow periodontal pocket was 51.1%, deep periodontal pocket was 4.9%, regular oral examination was 22.8%, correct brushing was 49.6%, and prepregnancy oral examination was 20.1%. DMFT was 2.27, and the caries filling ratio was 45.4%. The number of missing teeth increased with age (P < .001). Only 26.3% used dental floss more than once a day, 47.3% rinsed the mouth more than twice a day, and 46.9% cleaned their tongue coating every week. In addition, 99% of the pregnant women agreed that “oral health was vital to their lives” and 97.7% agreed that “regular oral examination was necessary.” ConclusionsThe oral health status amongst pregnant women in Shanghai was poor, but oral health awareness and attitudes were relatively high.

The AIUM Practice Parameter for the Performance of an Ultrasound Examination of the Abdomen and/or Retroperitoneum.

The AIUM Practice Parameter for the Performance of an Ultrasound Examination of the Abdomen and/or Retroperitoneum.

A miniaturized pre-calibration based Lissajous scanning fiber probe for endoscopic optical coherence tomography

In this paper we present a miniaturized pre-calibration based forward-viewing Lissajous scanning fiber probe for endoscopic optical coherence tomography (OCT). The probe is based on an asymmetric fiber cantilever driven by the piezoelectric bender to realize the two-dimensional (2D) Lissajous scanning, which can realize a relatively large scanning range under a low driving voltage. A capillary metal tube is mounted at the end of the main fiber to reduce the resonant frequency of the fiber cantilever. The relationship between the filling rate and the side-lobe number of the Lissajous scanning pattern is studied, and a method of selecting the orthogonal resonant frequency of the Lissajous scanning is proposed. Through the numerical simulation by COMSOL software, the structural parameters of the asymmetric fiber cantilever are determined. The orthogonal resonant frequencies of the asymmetric fiber cantilever are 169 Hz and 122 Hz. The lengths of the main imaging fiber, the auxiliary fiber and the metal capillary tube are 15.94 mm, 4.49 mm and 2 mm, respectively. The probe is fully packaged in a metal tube for endoscopic imaging. The focal spot and the working distance are 25 µm and 5 mm, respectively. The field of view is larger than 1.5 mm × 1.5 mm. The total rigid length and the outer diameter of the probe are 35 mm and 3.5 mm, respectively. The stability and repeatability of the Lissajous scanning trajectory, and the imaging stability with the rotation of the probe are investigated and verified. The probe is incorporated into a 50 kHz swept source OCT system. The axial resolution of the endoscopic OCT is 10.3 μm, and the imaging frame rate is 1 FPS (frames per second). The maximum signal-to-noise ratio of the imaging system is 110 dB. The imaging performance of the probe is validated by the 2D &lt;i&gt;en-face&lt;/i&gt; and three-dimensional volumetric OCT imaging of the high scattering sample and the biological tissue. The probe can be used for the endoscopic imaging of the human tooth. From the result we can distinguish the dental enamel, dental essence and the dental calculus. The developed forward-viewing Lissajous scanning fiber probe is expected to be used in dental applications such as early calculus detection.

Accuracy of dental calculus detection using digital radiography and image manipulation.

The aim of this study was to determine if image enhancement improves a clinician's ability to identify the presence of calculus on digital radiographs. Seventy-one hopeless teeth were collected from 34 patients. Teeth were stained with 1% methylene blue, the largest interproximal calculus deposit was scored, and photographs of each interproximal root surface were taken. The surface area of calculus deposit was determined as a percentage of the total interproximal root surface area. Digital radiographs of teeth taken before extraction were modified using the following enhancements: auto-contrast, emboss, invert, and sharpen. Radiographic presence of calculus was determined by two examiners. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for each examiner and enhancement. A receiver operating characteristic curve was used to compare differences between the image enhancements in the detection of dental calculus. The kappa statistic was used to compare ratings between examiners. None of the enhanced images were statistically superior to original images in identifying radiographic calculus (P> 0.05). The average sensitivity of digital radiography was 50%, average specificity was 82.2%, PPV was 94%, and NPV 23.2%. A threshold of >30% of interproximal root surface covered with calculus and increasing size of deposits were associated with improved detection (P< 0.05). Digital enhancements do not significantly improve radiographic detection of dental calculus. As area of calculus on the root surface and size of calculus deposits increased, sensitivity of detection also increased.

Effectiveness of a 655-nm InGaAsP diode laser to detect subgingival calculus in patients with periodontal disease.

Previous in vitro studies have proven laser fluorescence measurement using a 655-nm Indium Gallium Arsenide Phosphide (InGaAsP) based diode laser radiation to be a useful tool to detect subgingival calculus. The aim of this prospective study was to evaluate the 655-nm InGaAsP diode laser in detecting subgingival calculus in patients with periodontal disease compared with photographic assessment during periodontal surgery. Twelve patients (six women, six men) aged between 21 and 75 years with periodontitis scheduled for periodontal surgery were included in this prospective study. All laser fluorescence measurements were made before periodontal surgery. Intraoperatively a mucoperiostal flap was performed, subgingival calculus was visualized, and photographic images were taken. The presence of calculus was recorded for each evaluated site. A total of 115 tooth surface sites of 32 teeth from the 12 patients were evaluated before (laser) and during surgery (image). Compared with image evaluation the laser assessment showed a sensitivity of 0.70 (CI0.025 0.53 to CI0.975 0.83) and a specificity of 0.97 (CI0.025 0.85 to CI0.975 0.99). The overall probability to correctly detect subgingival calculus with the laser (accuracy) was 0.82 (CI0.025 0.74 to CI0.975 0.88). The 655-nm diode laser was able to detect subgingival calculus. Hence, the 655nm diode laser may be used as an additional tool for calculus detection in non-surgical periodontal therapy.

Ray sum image: its efficacy in renal tract calculus detection

To determine the efficacy of a ray sum image derived from computed tomography of the kidneys, ureters and bladder (CT KUB) in detecting renal tract calculi and whether this can replace the baseline abdominal radiograph (AXR). This is a retrospective study performed at a tertiary referral centre examining adult patients referred for urolithiasis who had undergone AXR within 24 hours of the diagnostic CT KUB. AXR and ray sum image for calculus visibility were reviewed blindly by two readers. Anteroposterior thickness of the patient, presence of excess gas/faecal material, calculus size, location, and mean attenuation were analysed to determine effect on the AXR and ray sum sensitivity. One hundred and fifty-two calculi were examined with ray sum image sensitivity of 44% (95% confidence interval [CI]: 36-52) and AXR 30% (95% CI: 22-38). Calculus size and mean attenuation significantly affected sensitivities of both ray sum and AXR. There was substantial agreement between the two techniques with κ(Kappa)=0.70 (95% CI: 0.58-0.81, p<0.001). Ray sum image as a post-processed image derived from CT KUB dataset may be a viable alternative to the baseline AXR in patients with CT proven urolithiasis. This would reduce patient radiation dose and streamline workflow in busy radiology and emergency departments.

Improved detection of subgingival calculus by laser fluorescence over differential reflectometry

Laser fluorescence (LF) and differential reflectometry (DR) are two new optical methods which have been used to help diagnose subgingival deposits of dental calculus. This study compared the performance of LF using the KEY3 laser system versus DR using the DetecTar system under controlled laboratory conditions designed to simulate clinical conditions as much as possible. A total of 30 extracted human posterior teeth were set in an anatomical configuration in stone typodonts with impression material replicating the periodontal soft tissues. LF was more accurate than DR (76.2% vs. 68.2%) and gave higher reproducibility (Bangdiwala’s B statistic 0.71 vs. 0.54). The better performance of LF makes it the preferred option of the two methods for detection of subgingival dental calculus.

An investigation into the clinical accuracy of twinkling artifacts in patients with urolithiasis smaller than 5 mm in comparison with computed tomography scanning.

Background:Ultrasound (US) is a non-invasive method used for the diagnosis of urolithiasis. If the size of the stone is <5 mm, it may be difficult to diagnose. This study aimed to compare the accuracy of twinkling artifact (TA) of color Doppler US imaging with unenhanced computed tomography (CT) for detecting urolithiasis <5 mm.Materials and Methods:This prospective study was conducted on 100 patients with suspected renal calculus presented to the emergency room at the Imam Khomeini Hospital of Ahwaz in 2018. The US findings such as posterior acoustic shadowing and TA were examined for their ability to detect urinary stones (greatest diameter ≤5 mm) using CT findings as the gold standard.Results:The mean size of renal stone was 3.43 ± 0.80 mm in CT and 3.49 ± 0.82 mm in color Doppler US. There was no significant difference between CT and color Doppler US report in quantification of urolithiasis sizes (P = 0.603). TA on color Doppler US was detected in 94 (94%) patients while posterior acoustic shadow was detected in 83 (83%) patients (P = 0.004). A significant difference was found between the TA and size of stones (P = 0.036). The sensitivity, accuracy, and positive predictive values of TA for the detection of calculus were 94%, 94%, and 100%, respectively.Conclusion:The results demonstrated that TA on color Doppler US could be a good and safe alternative imaging modality with comparable results with non-contrast-enhanced computed tomography for the sensitive detection of urolithiasis <5 mm.

PR396: Comparison of calculus detection among dental hygienists utilizing ultrasonic inserts

PR396: Comparison of calculus detection among dental hygienists utilizing ultrasonic inserts

In vitro and clinical evaluation of optical coherence tomography for the detection of subgingival calculus and root cementum.

This study evaluated the effectiveness of swept-source optical coherence tomography (ss-OCT) for detecting calculus and root cementum during periodontal therapy. Optical coherence tomography (OCT) images were taken before and after removal of subgingival calculus from extracted teeth and compared with non-decalcified histological sections. Porcine gingival sheets of various thicknesses were applied to the root surfaces of extracted teeth with calculus and OCT images were taken. OCT images were also taken before and after scaling and root planing (SRP) in human patients. In vitro, calculus was clearly detected as a white-gray amorphous structure on the root surface, which disappeared after removal. Cementum was identified as a thin, dark-gray layer. The calculus could not be clearly observed when soft tissues were present on the root surface. Clinically, supragingival calculus and cementum could be detected clearly with OCT, and subgingival calculus in the buccal cervical area of the anterior and premolar teeth was identified, which disappeared after SRP. Digital processing of the original OCT images was useful for clarifying the calculus. In conclusion, ss-OCT showed potential as a periodontal diagnostic tool for detecting cementum and subgingival calculus, although the practical applications of subgingival imaging remain limited.

Epidemiological and imaging features that can affect the detection of ureterolithiasis on ultrasound.

ObjectiveTo identify, in patients with clinical suspicion of ureterolithiasis, epidemiological and imaging features that affect calculus detection on ultrasound, as well as to compare ultrasound with multidetector computed tomography (MDCT).Materials and MethodsWe searched our database for patients who underwent ultrasound, followed by MDCT (if the ultrasound was negative), for suspected ureterolithiasis in an emergency setting. Patients were divided into three groups: positive ultrasound (US+); negative ultrasound/positive MDCT (US−/MDCT+); and negative ultrasound/negative MDCT (US−/MDCT−). We evaluated age, gender, ureterolithiasis laterality, location of the calculus within the ureter, body mass index, calculus diameter, and calculus attenuation on MDCT.ResultsOf a total of 292 cases of suspected ureterolithiasis, 155 (53.1%) were in the US+ group, 46 (15.7%) were in the US−/MDCT+ group, and 91 (31.2%) were in the US−/MDCT− group. There were no significant differences among the groups in terms of age, gender, ureterolithiasis laterality, and mean MDCT attenuation values. Distal ureterolithiasis was most common in the US+ group, and calculi at other ureteral locations were more common in the US−/MDCT+ group. The mean body mass index was significantly higher in the US−/MDCT+ group than in the US+ group, and the mean calculus diameter was significantly greater in the US+ group than in the US−/MDCT+ group.ConclusionA high body mass index, large calculus diameter, and calculus location in the distal third of the ureter are the major factors favoring ureterolithiasis detection on ultrasound.

In vitro performance of DIAGNOdent laser fluorescence device for dental calculus detection on human tooth root surfaces.

ObjectiveThis study assessed the reproducibility of a red diode laser device, and its capability to detect dental calculus in vitro on human tooth root surfaces.Material and methodsOn each of 50 extracted teeth, a calculus-positive and calculus-free root surface was evaluated by two independent examiners with a low-power indium gallium arsenide phosphide diode laser (DIAGNOdent) fitted with a periodontal probe-like sapphire tip and emitting visible red light at 655 nm wavelength. Laser autofluorescence intensity readings of examined root surfaces were scored on a 0–99 scale, with duplicate assessments performed using the laser probe tip directed both perpendicular and parallel to evaluated tooth root surfaces. Pearson correlation coefficients of untransformed measurements, and kappa analysis of data dichotomized with a >40 autofluorescence intensity threshold, were calculated to assess intra- and inter-examiner reproducibility of the laser device. Mean autofluorescence intensity scores of calculus-positive and calculus-free root surfaces were evaluated with the Student’s t-test.ResultsExcellent intra- and inter-examiner reproducibility was found for DIAGNOdent laser autofluorescence intensity measurements, with Pearson correlation coefficients above 94%, and kappa values ranging between 0.96 and 1.0, for duplicate readings taken with both laser probe tip orientations. Significantly higher autofluorescence intensity values were measured when the laser probe tip was directed perpendicular, rather than parallel, to tooth root surfaces. However, calculus-positive roots, particularly with calculus in markedly-raised ledges, yielded significantly greater mean DIAGNOdent laser autofluorescence intensity scores than calculus-free surfaces, regardless of probe tip orientation. DIAGNOdent autofluorescence intensity values >40 exhibited a stronger association with calculus (36.6 odds ratio) then measurements of ≥5 (20.1 odds ratio) when the laser probe tip was advanced parallel to root surfaces.ConclusionsExcellent intra- and inter-examiner reproducibility of autofluorescence intensity measurements was obtained with the DIAGNOdent laser fluorescence device on human tooth roots. Calculus-positive root surfaces exhibited significantly greater DIAGNOdent laser autofluorescence than calculus-free tooth roots, even with the laser probe tip directed parallel to root surfaces. These findings provide further in vitro validation of the potential utility of a DIAGNOdent laser fluorescence device for identifying dental calculus on human tooth root surfaces.

Sonographic twinkle artefact in renal calculus detection: Impact of scanning factors in a phantom model.

A common clinical use of the twinkle artefact is to detect and confirm renal calcification on ultrasound. There is however variable demonstration of this artefact using newer generation ultrasound machines. The purpose of this study was to assess the impact of altering multiple scanning factors on ultrasound machines from four major manufacturers on the demonstration of the twinkle artefact. Two custom-made phantoms and five-point Likert-like Scale were utilised. These phantoms contained a range of urinary calculi varying in size, composition, surface contour and depth. The calculi were serially imaged with each ultrasound machine, using manufacturers presets and varying just one imaging factor or parameter at a time. The documented twinkle artefact in the images were subsequently analysed, together with the imaging preset and factor changes that had been made. Those factors that had the greatest effect in order of impact were colour write priority, colour gain, transducer type, depth of calculus, acoustic power and size of calculus. Variability was also demonstrated between manufacturers. By isolating the effect of scanning factor changes, their importance and contribution to appearances in the ultrasound image can be assessed. Image interpretation in the clinical setting requires an understanding of the underlying physics, particularly in the evaluation of artefacts associated with renal calculi.

A multi-reader invitro study using porcine kidneys to determine the impact of integrated circuit detectors and iterative reconstruction on the detection accuracy, size measurement, and radiation dose for small (

Background Detection of small renal calculi has benefitted from recent advances in computed tomography (CT) scanner design. Information regarding observer performance when using state-of-the-art CT scanners for this application is needed. Purpose To assess observer performance and the impact of radiation dose for detection and size measurement of <4 mm renal stones using CT with integrated circuit detectors and iterative reconstruction. Material and Methods Twenty-nine <4 mm calcium oxalate stones were randomly placed in 20 porcine kidneys in an anthropomorphic phantom. Four radiologists used a workstation to record each calculus detection and size. JAFROC Figure of Merit (FOM), sensitivity, false positive detections, and calculus size were calculated. Results Mean calculus size was 2.2 ± 0.7 mm. The CTDIvol values corresponding to the automatic exposure control settings of 160, 80, 40, 25, and 10 Quality Reference mAs (QRM) were 15.2, 7.9, 4.2, 2.7, and 1.3 mGy, respectively. JAFROC FOM was ≥ 0.97 at ≥ 80 QRM, ≥ 0.89 at ≥ 25 QRM, and was inferior to routine dose (160 QRM) at 10 QRM (0.72, P < 0.05). Per-calculus sensitivity remained ≥ 85% for every reader at ≥ 25 QRM. Mean total false positive detections per reader were ≤ 3 at ≥ 80 QRM, but increased substantially for two readers ( ≥ 12) at ≤ 40 QRM. Measured calculus size significantly decreased at ≤ 25 QRM ( P ≤ 0.01). Conclusion Using low dose renal CT with iterative reconstruction and ≥ 25 QRM results in high sensitivity, but false positive detections increase for some readers at very low dose levels (≤ 40 QRM). At very low doses with iterative reconstruction, measured calculus size will artifactually decrease.