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RATIONALE AND OBJECTIVES: To assess image quality and radiation dose of ultra-high-pitch CT pulmonary angiography (CTPA) with free-breathing technique for diagnosis of pulmonary embolism using a photon-counting detector (PCD) CT compared to matched energy-integrating detector (EID)-based single-energy CTPA. MATERIALS AND METHODS: Fifty-one PCD-CTPAs were prospectively compared to 51 CTPAs on a third-generation dual-source EID-CT. CTPAs were acquired with an ultra-high-pitch protocol with free-breathing technique (40 mL contrast medium, pitch 3.2) at 140 kV (PCD) and 70-100 kV (EID). Iodine maps were reconstructed from spectral PCD-CTPAs. Image quality of CTPAs and iodine maps was assessed independently by three radiologists. Additionally, CT attenuation numbers within pulmonary arteries as well as signal-to-noise and contrast-to-noise ratios (SNR, CNR) were compared. Administered radiation dose was compared. RESULTS: CT attenuation was higher in the PCD-group (all P < 0.05). CNR and SNR were higher in lobar pulmonary arteries in PCD-CTPAs (P < 0.05), whereas no difference was ascertained within the pulmonary trunk (P > 0.05). Image quality of PCD-CTPA was rated best by all readers (excellent/good image quality in 96.1% of PCD-CTPAs vs. 50.9% of EID-CTPAs). PCD-CT produced no non-diagnostic scans vs. three non-diagnostic (5.9%) EID-CTPAs. Radiation dose was lower with PCD-CT than with EID-CT (effective dose 1.33 ± 0.47 vs. 1.80 ± 0.82 mSv; all P < 0.05). CONCLUSION: Ultra-high-pitch CTPA with free-breathing technique with PCD-CT allows for superior image quality with significantly reduced radiation dose and full spectral information. With the ultra-high pitch, only PCD-CTPA enables reconstruction of iodine maps containing additional functional information.
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INTRODUCTION: Cochlear duct length (CDL) measurement plays a role in the context of individualized cochlear implant (CI) surgery regarding an individualized selection and implantation of the CI electrode carrier and an efficient postoperative anatomy-based fitting process. The level of detail of the preoperative temporal bone CT scan depends on the imaging modality with major impact on CDL measurements and CI electrode contact position determination. The aim of this study was to evaluate the accuracy of perioperative CDL measurements and electrode contact determination in photon-counting CT (PCCT). METHODS: Ten human fresh-frozen petrous bone specimens were examined with a first-generation PCCT. A clinically applicable radiation dose of 27.1 mGy was used. Scans were acquired before and after CI insertion. Postoperative measurement of the CDL was conducted using an otological planning software and 3D-curved multiplanar reconstruction. Investigation of electrode contact position was performed by two respective observers. Measurements were compared with a conventional multislice CT and to a high-resolution flat-panel volume CT with secondary reconstructions. RESULTS: Pre- and postoperative CDL measurements in PCCT images showed no significant difference to high-resolution flat-panel volume CT. Postoperative CI electrode contact determination was also as precise as the flat-panel CT-based assessment. PCCT and flat-panel volume CT were equivalent concerning interobserver variability. CONCLUSION: CDL measurement with PCCT was equivalent to flat-panel volume CT with secondary reconstructions. PCCT enabled highly precise postoperative CI electrode contact determination with substantial advantages over conventional multislice CT scanners.
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Implantación Coclear , Humanos , Implantación Coclear/métodos , Conducto Coclear/diagnóstico por imagen , Conducto Coclear/cirugía , Tomografía Computarizada por Rayos X/métodos , Implantes Cocleares , Fotones , Hueso Petroso/diagnóstico por imagen , Hueso Petroso/cirugía , Tomografía Computarizada Multidetector/métodos , Angiografía/métodosRESUMEN
PURPOSE: To compare suprapubic access (SPA) and transurethral catheterization (TUC) in voiding cystourethrogram (VCUG). METHODS: Retrospective single-center evaluation of 311 VCUG performed in male patients under 12 years of age. Two study groups were built based on the bladder access method. TUC was performed in 213 patients, whereas 98 received SPA. The groups were compared regarding the procedural switch rate, the complication rate, radiation parameters, the amount of contrast media applied and the examination quality. Complications were graded in minor (contrast leakage, premature termination of the examination) and major (fever, urinary tract infection, bladder perforation). Fluoroscopy time and radiation parameters were compared. Examination quality was assessed based on the satisfactory acquisition of fluoroscopic images using a four-point Likert scale. RESULTS: In 9% of the SPA examinations a method switch to TUC was necessary. The minor complication rate was 1.9% for TUC and 35.7% for SPA (p < 0.001). The major complication rate was 0.9% for TUC and 2% for SPA (p > 0.05). Mean fluoroscopy time and radiation dose were significantly lower in TUC (TUC, 26 ± 19 s, 0.6 ± 1.2 µGy·m2; SPA, 38 ± 33 s, 1.7 ± 2.9 µGy·m2; p = 0.01/0.001). There was no significant difference regarding the amount of contrast media applied (TUC, 62 ± 40 mL; SPA, 66 ± 41 mL; p > 0.05) and the examination quality with full diagnostic quality achieved in 88% of TUC and 89% of SPA examinations (p > 0.05). CONCLUSIONS: As TUC provides significantly lower radiation exposure and less periprocedural complications, it should be the primary bladder access route for VCUG in pediatric male patients.
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RATIONALE AND OBJECTIVES: This study aims to compare the diagnostic confidence of photon-counting detector CT angiography (PCD-CTA) depending on the used vascular reformatting kernels with digital subtraction angiography (DSA) as diagnostic reference standard in peripheral arterial occlusive disease (PAOD). MATERIAL AND METHODS: In 39 patients, 45 lower extremity PCD-CTA with subsequent DSA were analyzed. Advanced PAOD (Fontaine stage 4) was ascertained in 77.8% of patients. CTA post-processing comprised three vascular kernels (Bv36/48/56). Objective image quality assessment included vessel attenuation, image noise, contrast-to-noise (CNR) and signal-to-noise ratios (SNR). Subjective evaluation of calcium blooming, vessel sharpness, luminal attenuation and image noise was performed by three radiologists. Diagnostic performance and concordance to DSA were assessed. RESULTS: The luminal attenuation remained kernel-independent constant. With sharper kernels, image noise increased substantially, while SNR and CNR decreased. Subjective reduction of calcium blooming and increased vessel sharpness were noted for the sharp Bv56 kernel. While sensitivity in stenosis quantification was comparable between kernels (81.6% vs. 81.5% vs. 81.0%, p = 0.797), specificity increased slightly higher sharpness (71.1% vs. 76.9% vs. 79.6%, p = 0.067). Diagnostic concordance of stenosis ratings compared to DSA increased likewise (Bv36 vs. Bv56, p = 0.002). Severe crural vessel calcifications had no influence on sensitivity, regardless of kernel selection. Contrarily, specificity was substantially worse in severely calcified tibial vessels but could be improved by using the sharp Bv56 kernel (Bv36 vs. Bv56 p = 0.024). Diagnostic confidence was highest for Bv56. CONCLUSION: In lower leg PCD-CTA, sharp convolution kernels increase diagnostic confidence compared to DSA by improved vessel delineation and reduced calcium blooming with acceptable image noise.
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Angiografía de Substracción Digital , Angiografía por Tomografía Computarizada , Enfermedad Arterial Periférica , Sensibilidad y Especificidad , Humanos , Angiografía de Substracción Digital/métodos , Femenino , Masculino , Enfermedad Arterial Periférica/diagnóstico por imagen , Anciano , Angiografía por Tomografía Computarizada/métodos , Persona de Mediana Edad , Anciano de 80 o más Años , Relación Señal-Ruido , Interpretación de Imagen Radiográfica Asistida por Computador/métodos , Fotones , AdultoRESUMEN
Photon-counting detector (PCD)-CT allows for reconstruction of virtual non-iodine (VNI) images from contrast-enhanced datasets. This study assesses the diagnostic performance of aortic valve calcification scoring (AVCS) derived from VNI datasets generated with a 1st generation clinical dual-source PCD-CT. AVCS was evaluated in 123 patients (statistical analysis only comprising patients with aortic valve calcifications [n = 56; 63.2 ± 11.6 years]), who underwent contrast enhanced electrocardiogram-gated (either prospective or retrospective or both) cardiac CT on a clinical PCD system. Patient data was reconstructed at 70 keV employing a VNI reconstruction algorithm. True non-contrast (TNC) scans at 70 keV without quantum iterative reconstruction served as reference in all individuals. Subgroup analysis was performed in 17 patients who received both, prospectively and retrospectively gated contrast enhanced scans (n = 8 with aortic valve calcifications). VNI images with prospective/retrospective gating had an overall sensitivity of 69.2%/56.0%, specificity of 100%/100%, accuracy of 85.4%/81.0%, positive predictive value of 100%/100%, and a negative predictive value of 78.2%/75.0%. VNI images with retrospective gating achieved similar results. For both gating approaches, AVCSVNI showed high correlation (r = 0.983, P < 0.001 for prospective; r = 0.986, P < 0.001 for retrospective) with AVCSTNC. Subgroup analyses demonstrated excellent intra-individual correlation between different acquisition modes (r = 0.986, P < 0.001). Thus, VNI images derived from cardiac PCD-CT allow for excellent diagnostic performance in the assessment of AVCS, suggesting potential for the omission of true non-contrast scans in the clinical workup of patients with aortic calcifications.
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Estenosis de la Válvula Aórtica , Válvula Aórtica , Válvula Aórtica/patología , Calcinosis , Yodo , Humanos , Estudios Retrospectivos , Válvula Aórtica/diagnóstico por imagen , Estudios Prospectivos , Tomografía Computarizada por Rayos X/métodos , AngiografíaRESUMEN
BACKGROUND AND AIMS: This study aims to compare the performance of first-generation dual-source photon-counting detector computed tomography (PCD-CT) to third-generation dual-source energy-integrating detector (EID-CT) regarding stent imaging in the femoral arterial runoff. METHODS: Continuous extracorporeal perfusion was established in 1 human cadaver using an inguinal and infragenicular access and peristaltic pump. Seven peripheral stents were implanted into both superior femoral arteries by means of percutaneous angioplasty. Radiation dose-equivalent CT angiographies (high-/medium-/low-dose: 10/5/3 mGy) with constant tube voltage of 120 kVp, matching iterative reconstruction algorithm levels, and convolution kernels were used both with PCD-CT and EID-CT. In-stent lumen visibility, luminal and in-stent attenuation as well as contrast-to-noise ratio (CNR) were assessed via region of interest and diameter measurements. Results were compared using analyses of variance and regression analyses. RESULTS: Maximum in-stent lumen visibility achieved with PCD-CT was 94.48% ± 2.62%. The PCD-CT protocol with the lowest lumen visibility (BV40: 78.93% ± 4.67%) performed equal to the EID-CT protocol with the best lumen visibility (BV59: 79.49% ± 2.64%, P > 0.999). Photon-counting detector CT yielded superior CNR compared with EID-CT regardless of kernel and dose level ( P < 0.001). Maximum CNR was 48.8 ± 17.4 in PCD-CT versus 31.28 ± 5.7 in EID-CT (both BV40, high-dose). The theoretical dose reduction potential of PCD-CT over EID-CT was established at 88% (BV40), 83% (BV48/49), and 73% (BV59/60), respectively. In-stent attenuation was not significantly different from luminal attenuation outside stents in any protocol. CONCLUSIONS: With superior lumen visibility and CNR, PCD-CT allowed for noticeable dose reduction over EID-CT while maintaining image quality in a continuously perfused human cadaveric model.
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Fotones , Tomografía Computarizada por Rayos X , Humanos , Fantasmas de Imagen , Tomografía Computarizada por Rayos X/métodos , Stents , CadáverRESUMEN
BACKGROUND. Dual-energy CT pulmonary angiography (CTPA) with energy-integrating detector (EID) technology is limited by the inability to use high-pitch technique. OBJECTIVE. The purpose of this study was to compare the image quality of anatomic images and iodine maps between high-pitch photon-counting detector (PCD) CTPA and dual-energy EID CTPA. METHODS. This prospective study included 117 patients (70 men and 47 women; median age, 65 years) who underwent CTPA to evaluate for pulmonary embolism between March 2022 and November 2022. Fifty-eight patients were randomized to undergo PCD CTPA (pitch, 2.0), and 59 were randomized to undergo EID CTPA (pitch, 0.55). For each examination, 120-kV polychromatic images, 60-keV virtual monogenetic images (VMIs), and iodine maps were reconstructed. One radiologist measured CNR and SNR. Three radiologists independently assessed subjective image quality (on a scale of 1-4, with a score of 1 denoting highest quality). Radiation dose was recorded. RESULTS. SNR and CNR were higher for PCD CTPA than for EID CTPA for polychromatic images and VMIs, for all assessed vessels other than the left upper lobe artery. For example, for PCD CTPA versus EID CTPA, the right lower lobe artery on polychromatic images had an SNR of 34.5 versus 28.0 (p = .003) and a CNR of 29.2 versus 24.4 (p = .001), and on VMIs it had an SNR of 43.2 versus 32.7 (p = .005) and a CNR of 37.4 versus 29.3 (p = .002). For both scanners for readers 1 and 2, the median image quality score for polychromatic images and VMIs was 1, although distributions indicated significantly better scores for PCD CTPA than for EID CTPA for polychromatic images for reader 1 (p = .02) and reader 2 (p = .005) and for VMIs for reader 1 (p = .001) and reader 2 (p = .006). The image quality of anatomic image sets was not different between PCD CTPA and EID CTPA for reader 3 (p > .05). The image quality of iodine maps was not different between PCD CTPA and EID CTPA for any reader (p > .05). For PCD CTPA versus EID CTPA, the CTDIvol was 3.9 versus 4.5 mGy (p = .03), and the DLP was 123.5 mGy × cm versus 157.0 mGy × cm (p < .001). CONCLUSION. High-pitch PCD CTPA provided anatomic images with better subjective and objective image quality versus dual-energy EID CTPA, with lower radiation dose. Iodine maps showed no significant difference in image quality between scanners. CLINICAL IMPACT. CTPA may benefit from the PCD CT technique.
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Yodo , Masculino , Humanos , Femenino , Anciano , Estudios Prospectivos , Fotones , Fantasmas de Imagen , Tomografía Computarizada por Rayos X/métodos , Dosis de RadiaciónRESUMEN
This retrospective study aims to provide an intra-individual comparison of aortic CT angiographies (CTAs) using first-generation photon-counting-detector CT (PCD-CT) and third-generation energy-integrating-detector CT (EID-CT). High-pitch CTAs were performed with both scanners and equal contrast-agent protocols. EID-CT employed automatic tube voltage selection (90/100 kVp) with reference tube current of 434/350 mAs, whereas multi-energy PCD-CT scans were generated with fixed tube voltage (120 kVp), image quality level of 64, and reconstructed as 55 keV monoenergetic images. For image quality assessment, contrast-to-noise ratios (CNRs) were calculated, and subjective evaluation (overall quality, luminal contrast, vessel sharpness, blooming, and beam hardening) was performed independently by three radiologists. Fifty-seven patients (12 women, 45 men) were included with a median interval between examinations of 12.7 months (interquartile range 11.1 months). Using manufacturer-recommended scan protocols resulted in a substantially lower radiation dose in PCD-CT (size-specific dose estimate: 4.88 ± 0.48 versus 6.28 ± 0.50 mGy, p < 0.001), while CNR was approximately 50% higher (41.11 ± 8.68 versus 27.05 ± 6.73, p < 0.001). Overall image quality and luminal contrast were deemed superior in PCD-CT (p < 0.001). Notably, EID-CT allowed for comparable vessel sharpness (p = 0.439) and less pronounced blooming and beam hardening (p < 0.001). Inter-rater agreement was good to excellent (0.58-0.87). Concluding, aortic PCD-CTAs facilitate increased image quality with significantly lower radiation dose compared to EID-CTAs.
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This study evaluated the influence of different vascular reconstruction kernels on the image quality of CT angiographies of the lower extremity runoff using a 1st-generation photon-counting-detector CT (PCD-CT) compared with dose-matched examinations on a 3rd-generation energy-integrating-detector CT (EID-CT). Inducing continuous extracorporeal perfusion in a human cadaveric model, we performed CT angiographies of eight upper leg arterial runoffs with radiation dose-equivalent 120 kVp acquisition protocols (CTDIvol 5 mGy). Reconstructions were executed with different vascular kernels, matching the individual modulation transfer functions between scanners. Signal-to-noise-ratios (SNR) and contrast-to-noise-ratios (CNR) were computed to assess objective image quality. Six radiologists evaluated image quality subjectively using a forced-choice pairwise comparison tool. Interrater agreement was determined by calculating Kendall's concordance coefficient (W). The intraluminal attenuation of PCD-CT images was significantly higher than of EID-CT (414.7 ± 27.3 HU vs. 329.3 ± 24.5 HU; p < 0.001). Using comparable kernels, image noise with PCD-CT was significantly lower than with EID-CT (p ≤ 0.044). Correspondingly, SNR and CNR were approximately twofold higher for PCD-CT (p < 0.001). Increasing the spatial frequency for PCD-CT reconstructions by one level resulted in similar metrics compared to EID-CT (CNRfat; EID-CT Bv49: 21.7 ± 3.7 versus PCD-CT Bv60: 21.4 ± 3.5). Overall image quality of PCD-CTA achieved ratings superior to EID-CTA irrespective of the used reconstruction kernels (best: PCD-CT Bv60; worst: EID-CT Bv40; p < 0.001). Interrater agreement was good (W = 0.78). Concluding, PCD-CT offers superior intraluminal attenuation, SNR, and CNR compared to EID-CT in angiographies of the upper leg arterial runoff. Combined with improved subjective image quality, PCD-CT facilitates the use of sharper convolution kernels and ultimately bears the potential of improved vascular structure assessability.
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Angiografía por Tomografía Computarizada , Pierna , Humanos , Angiografía por Tomografía Computarizada/métodos , Fantasmas de Imagen , Fotones , Tomografía Computarizada por Rayos X/métodos , AngiografíaRESUMEN
OBJECTIVES: While established for energy-integrating detector computed tomography (CT), the effect of virtual monoenergetic imaging (VMI) and iterative metal artifact reduction (iMAR) in photon-counting detector (PCD) CT lacks thorough investigation. This study evaluates VMI, iMAR, and combinations thereof in PCD-CT of patients with dental implants. MATERIAL AND METHODS: In 50 patients (25 women; mean age 62.0 ± 9.9 years), polychromatic 120 kVp imaging (T3D), VMI, T3DiMAR, and VMIiMAR were compared. VMIs were reconstructed at 40, 70, 110, 150, and 190 keV. Artifact reduction was assessed by attenuation and noise measurements in the most hyper- and hypodense artifacts, as well as in artifact-impaired soft tissue of the mouth floor. Three readers subjectively evaluated artifact extent and soft tissue interpretability. Furthermore, new artifacts through overcorrection were assessed. RESULTS: iMAR reduced hyper-/hypodense artifacts (T3D 1305.0/-1418.4 versus T3DiMAR 103.2/-46.9 HU), soft tissue impairment (106.7 versus 39.7 HU), and image noise (16.9 versus 5.2 HU) compared to non-iMAR datasets (p ≤ 0.001). VMIiMAR ≥ 110 keV subjectively enhanced artifact reduction over T3DiMAR (p ≤ 0.023). Without iMAR, VMI displayed no measurable artifact reduction (p ≥ 0.186) and facilitated no significant denoising over T3D (p ≥ 0.366). However, VMI ≥ 110 keV reduced soft tissue impairment (p ≤ 0.009). VMIiMAR ≥ 110 keV resulted in less overcorrection than T3DiMAR (p ≤ 0.001). Inter-reader reliability was moderate/good for hyperdense (0.707), hypodense (0.802), and soft tissue artifacts (0.804). CONCLUSION: While VMI alone holds minimal metal artifact reduction potential, iMAR post-processing enabled substantial reduction of hyperdense and hypodense artifacts. The combination of VMI ≥ 110 keV and iMAR resulted in the least extensive metal artifacts. CLINICAL RELEVANCE: Combining iMAR with VMI represents a potent tool for maxillofacial PCD-CT with dental implants achieving substantial artifact reduction and high image quality. KEY POINTS: ⢠Post-processing of photon-counting CT scans with an iterative metal artifact reduction algorithm substantially reduces hyperdense and hypodense artifacts arising from dental implants. ⢠Virtual monoenergetic images presented only minimal metal artifact reduction potential. ⢠The combination of both provided a considerable benefit in subjective analysis compared to iterative metal artifact reduction alone.
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Artefactos , Implantes Dentales , Humanos , Femenino , Persona de Mediana Edad , Anciano , Reproducibilidad de los Resultados , Metales , Tomografía Computarizada por Rayos X/métodos , AlgoritmosRESUMEN
OBJECTIVE: To evaluate the image quality of an ultra-low contrast medium and radiation dose CT pulmonary angiography (CTPA) protocol for the diagnosis of acute pulmonary embolism using a clinical photon-counting detector (PCD) CT system and compare its performance to a dual-energy-(DE)-CTPA protocol on a conventional energy-integrating detector (EID) CT system. METHODS: Sixty-four patients either underwent CTPA with the novel scan protocol on the PCD-CT scanner (32 patients, 25 mL, CTDIvol 2.5 mGy·cm) or conventional DE-CTPA on a third-generation dual-source EID-CT (32 patients, 50 mL, CTDIvol 5.1 mGy·cm). Pulmonary artery CT attenuation, signal-to-noise ratio, and contrast-to-noise-ratio were assessed as objective criteria of image quality, while subjective ratings of four radiologists were compared at 60 keV using virtual monoenergetic imaging and polychromatic standard reconstructions. Interrater reliability was determined by means of the intraclass correlation coefficient (ICC). Effective dose was compared between patient cohorts. RESULTS: Subjective image quality was deemed superior by all four reviewers for 60-keV PCD scans (excellent or good ratings in 93.8% of PCD vs. 84.4% of 60 keV EID scans, ICC = 0.72). No examinations on either system were considered "non-diagnostic." Objective image quality parameters were significantly higher in the EID group (mostly p < 0.001), both in the polychromatic reconstructions and at 60 keV. The ED (1.4 vs. 3.3 mSv) was significantly lower in the PCD cohort (p < 0.001). CONCLUSIONS: PCD-CTPA allows for considerable reduction of contrast medium and radiation dose in the diagnosis of acute pulmonary embolism, while maintaining good to excellent image quality compared to conventional EID-CTPA. CLINICAL RELEVANCE STATEMENT: Clinical PCD-CT allows for spectral assessment of pulmonary vasculature with high scan speed, which is beneficial in patients with suspected pulmonary embolism, frequently presenting with dyspnea. Simultaneously PCD-CT enables substantial reduction of contrast medium and radiation dose. KEY POINTS: ⢠The clinical photon-counting detector CT scanner used in this study allows for high-pitch multi-energy acquisitions. ⢠Photon-counting computed tomography allows for considerable reduction of contrast medium and radiation dose in the diagnosis of acute pulmonary embolism. ⢠Subjective image quality was rated best for 60-keV photon-counting scans.
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Reducción Gradual de Medicamentos , Embolia Pulmonar , Humanos , Reproducibilidad de los Resultados , Tomografía Computarizada por Rayos X/métodos , Embolia Pulmonar/diagnóstico por imagen , Arteria Pulmonar/diagnóstico por imagen , Fotones , Fantasmas de ImagenRESUMEN
OBJECTIVES: Detailed visualization of the arterial runoff is mandatory for the assessment of peripheral arterial occlusive disease. This study aims to compare the performance of a first-generation photon-counting detector computed tomography (PCD-CT) to a third-generation energy-integrating detector CT (EID-CT). MATERIALS AND METHODS: Computed tomography angiographies of 8 upper leg arterial runoffs were performed on human cadaveric models with continuous extracorporeal perfusion. For both PCD-CT and EID-CT, radiation dose-equivalent 120 kVp acquisition protocols (low-/medium-/high-dose: CTDI Vol = 3/5/10 mGy) were used. All scans were performed with standard collimation (PCD-CT: 144 × 0.4 mm; EID-CT: 96 × 0.6 mm), a pitch factor of 0.4, and a gantry rotation time of 1.0 second. Reformatting of data included the use of comparable vascular kernels (Bv 48/49), a slice thickness and increment of 1.0 mm, and a field of view of 150 × 150 mm. Eight radiologists evaluated image quality independently using a browser-based pairwise forced-choice comparison setup. Kendall concordance coefficient ( W ) was calculated to estimate interrater agreement. Signal-to-noise ratio and contrast-to-noise ratio (CNR) were compared based on 1-way analyses of variance and linear regression analysis. RESULTS: Low-dose PCD-CT achieved superior signal-to-noise ratio/CNR values compared with high-dose EID-CT ( P < 0.001). Linear regression analysis suggested that an EID-CT scan with a CTDI Vol of at least 15.5 mGy was required to match the CNR value of low-dose PCD-CT. Intraluminal contrast attenuation was higher in PCD-CT than EID-CT, irrespective of dose level (415.0 ± 31.9 HU vs 329.2 ± 29.4 HU; P < 0.001). Subjective image quality of low-dose PCD-CT was considered superior to high-dose EID-CT ( P < 0.001). Interrater agreement was high ( W = 0.989). CONCLUSIONS: Using cadaveric models with continuous extracorporeal perfusion allows for intraindividual image quality comparisons between PCD-CT and EID-CT on variable dose levels. With superior luminal contrast attenuation and denoising in angiographies of the peripheral arterial runoff, PCD-CT displayed potential for radiation saving of up to 83% compared with EID-CT.
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Angiografía por Tomografía Computarizada , Tomografía Computarizada por Rayos X , Humanos , Angiografía por Tomografía Computarizada/métodos , Fantasmas de Imagen , Tomografía Computarizada por Rayos X/métodos , Relación Señal-Ruido , Fotones , CadáverRESUMEN
OBJECTIVES: We developed a novel human cadaveric perfusion model with continuous extracorporeal femoral perfusion suitable for performing intra-individual comparison studies, training of interventional procedures and preclinical testing of endovascular devices. Objective of this study was to introduce the techniques and evaluate the feasibility for realistic computed tomography angiography (CTA), digital subtraction angiography (DSA) including vascular interventions, and intravascular ultrasound (IVUS). METHODS: The establishment of the extracorporeal perfusion was attempted using one formalin-fixed and five fresh-frozen human cadavers. In all specimens, the common femoral and popliteal arteries were prepared, introducer sheaths inserted, and perfusion established by a peristaltic pump. Subsequently, we performed CTA and bilateral DSA in five cadavers and IVUS on both legs of four donors. Examination time without unintentional interruption was measured both with and without non-contrast planning CT. Percutaneous transluminal angioplasty and stenting was performed by two interventional radiologists on nine extremities (five donors) using a broad spectrum of different intravascular devices. RESULTS: The perfusion of the upper leg arteries was successfully established in all fresh-frozen but not in the formalin-fixed cadaver. The experimental setup generated a stable circulation in each procedure (ten upper legs) for a period of more than six hours. Images acquired with CT, DSA and IVUS offered a realistic impression and enabled the sufficient visualization of all examined vessel segments. Arterial cannulating, percutaneous transluminal angioplasty as well as stent deployment were feasible in a way that is comparable to a vascular intervention in vivo. The perfusion model allowed for introduction and testing of previously not used devices. CONCLUSIONS: The continuous femoral perfusion model can be established with moderate effort, works stable, and is utilizable for medical imaging of the peripheral arterial system using CTA, DSA and IVUS. Therefore, it appears suitable for research studies, developing skills in interventional procedures and testing of new or unfamiliar vascular devices.
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Pierna , Tomografía Computarizada por Rayos X , Humanos , Angiografía de Substracción Digital , Perfusión , Cadáver , Formaldehído , Ultrasonografía IntervencionalRESUMEN
PURPOSE: This cadaveric study compared image quality between a third-generation dual-source CT scanner with energy-integrating detector technology (EID) and a first-generation CT system employing a photon-counting detector (PCD) for the cervical spine in ultrahigh-resolution mode. METHODS: The cervical spine of eight formalin-fixed full-body cadaveric specimens was scanned with both CT systems using 140 kVp scan protocols matched for CTDIvol (full-dose; low-dose; ultralow-dose; 10 mGy; 3 mGy; 1 mGy). Images were reconstructed with 1 mm slice thickness and 0.5 mm increment. Three radiologists rated overall subjective image quality based on an equidistant five-point scale with the intraclass correlation coefficient (ICC) calculated for assessment of interobserver reliability. Contrast-to-noise ratios were calculated individually for bone (CNRbone) and muscle tissue (CNRmuscle) to provide objective criteria of image analysis. RESULTS: Subjective image quality, as well as CNRbone, and CNRmuscle were each superior for PCD-CT compared to EID-CT among dose-matched scan protocol pairs (all p < 0.05). Between full-dose EID-CT and low-dose PCD-CT, subjective image quality was equal (p = 0.903), while superior quantitative results regarding the latter were ascertained (both p < 0.001). Similarly, objective analysis determined higher CNRbone, and CNRmuscle in ultralow-dose PCD-CT compared to low-dose EID-CT (both p < 0.001), while readers considered the image quality of the respective studies comparable (p > 0.99). Interobserver reliability was good, denoted by an ICC of 0.861 (95 % confidence interval: 0.788 - 0.914; p < 0.001). CONCLUSIONS: In cervical spine examinations, both subjective and objective image quality of PCD-CT were superior to EID-CT in comparison of scan protocols with corresponding dose levels, suggesting potential for significantly reducing the radiation exposure without compromising image quality.
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Cadmio , Tomografía Computarizada por Rayos X , Humanos , Reproducibilidad de los Resultados , Tomografía Computarizada por Rayos X/métodos , Fantasmas de Imagen , Vértebras Cervicales/diagnóstico por imagen , CadáverRESUMEN
OBJECTIVES: This study investigated the feasibility and image quality of ultra-low-dose unenhanced abdominal CT using photon-counting detector technology and tin prefiltration. MATERIALS AND METHODS: Employing a first-generation photon-counting CT scanner, eight cadaveric specimens were examined both with tin prefiltration (Sn 100 kVp) and polychromatic (120 kVp) scan protocols matched for radiation dose at three different levels: standard-dose (3 mGy), low-dose (1 mGy) and ultra-low-dose (0.5 mGy). Image quality was evaluated quantitatively by means of contrast-to-noise-ratios (CNR) with regions of interest placed in the renal cortex and subcutaneous fat. Additionally, three independent radiologists performed subjective evaluation of image quality. The intraclass correlation coefficient was calculated as a measure of interrater reliability. RESULTS: Irrespective of scan mode, CNR in the renal cortex decreased with lower radiation dose. Despite similar mean energy of the applied x-ray spectrum, CNR was superior for Sn 100 kVp over 120 kVp at standard-dose (17.75 ± 3.51 vs. 14.13 ± 4.02), low-dose (13.99 ± 2.6 vs. 10.68 ± 2.17) and ultra-low-dose levels (8.88 ± 2.01 vs. 11.06 ± 1.74) (all p ≤ 0.05). Subjective image quality was highest for both standard-dose protocols (score 5; interquartile range 5-5). While no difference was ascertained between Sn 100 kVp and 120 kVp examinations at standard and low-dose levels, the subjective image quality of tin-filtered scans was superior to 120 kVp with ultra-low radiation dose (p < 0.05). An intraclass correlation coefficient of 0.844 (95% confidence interval 0.763-0.906; p < 0.001) indicated good interrater reliability. CONCLUSIONS: Photon-counting detector CT permits excellent image quality in unenhanced abdominal CT with very low radiation dose. Employment of tin prefiltration at 100 kVp instead of polychromatic imaging at 120 kVp increases the image quality even further in the ultra-low-dose range of 0.5 mGy.
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Background Posttraumatic CT imaging of the elbow can be challenging when patient mobility is limited. Gantry-free cone-beam CT (CBCT) with a twin robotic radiography system offers greater degrees of positioning freedom for three-dimensional elbow scans over gantry-based multidetector CT (MDCT), but studies analyzing their clinical value remain lacking. Purpose To investigate the diagnostic performance of gantry-free CBCT versus two-dimensional radiography in adults and children with acute elbow trauma. Materials and Methods In a retrospective study, consecutive patients with elbow trauma and positioning difficulty in a gantry-based MDCT who underwent three-dimensional elbow imaging with a gantry-free CBCT after radiography were enrolled between January 2021 and April 2022 at a tertiary care university hospital. Imaging data sets were independently analyzed for fracture presence, articular involvement, and multi-fragment injuries by three radiologists. Diagnostic performance was calculated individually with surgical reports serving as the reference standard. Differences between radiography and CBCT were compared with the McNemar test. Diagnostic confidence was estimated subjectively by each reader, and results were compared with the Wilcoxon signed-rank test. Results Elbow examinations of 23 adults and children (mean age ± SD, 49 years ± 23; seven women) were included with individual assessment of humerus, radius, and ulna (69 bones; 36 fractured). Multi-fragmentary fracture patterns and involvement of articular surfaces were ascertained in 28 and 30 bones, respectively. CBCT allowed for similar or higher sensitivity compared with radiography in the assessment of fractures (range for three readers, 94%-100% vs 72%-81%; respectively, P ≤ .06-.008), articular surface involvement (90%-97% vs 73%-87%; P ≤ .25), and multi-fragmentary patterns (96%-96% vs 68%-75%; P ≤ .03). Readers' diagnostic confidence improved considerably with access to CBCT data sets versus radiographs (all P ≤ .001). For CBCT, the median dose-length product was 70.9 mGy · cm, and the volume CT dose index was 4.4 mGy. Conclusion In acute elbow injuries, gantry-free cone-beam CT enabled improved detection of fractures, articular involvement, and multi-fragmentary patterns compared with two-dimensional radiography. Published under a CC BY 4.0 license Online supplemental material is available for this article.
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Fracturas Óseas , Procedimientos Quirúrgicos Robotizados , Adulto , Niño , Humanos , Femenino , Dosis de Radiación , Codo , Estudios Retrospectivos , Tomografía Computarizada de Haz Cónico/métodos , Fracturas Óseas/diagnóstico por imagenRESUMEN
OBJECTIVES: Hardening the x-ray beam, tin prefiltration is established for imaging of high-contrast subjects in energy-integrating detector computed tomography (EID-CT). With this work, we aimed to investigate the dose-saving potential of spectral shaping via tin prefiltration in photon-counting detector CT (PCD-CT) of the temporal bone. METHODS: Deploying dose-matched scan protocols with and without tin prefiltration on a PCD-CT and EID-CT system (low-/intermediate-/full-dose: 4.8/7.6-7.7/27.0-27.1 mGy), 12 ultra-high-resolution examinations were performed on each of 5 cadaveric heads. While 120 kVp was applied for standard imaging, the protocols with spectral shaping used the highest potential available with tin prefiltration (EID-CT: Sn 150 kVp, PCD-CT: Sn 140 kVp). Contrast-to-noise ratios and dose-saving potential by spectral shaping were computed for each scanner. Three radiologists independently assessed the image quality of each examination with the intraclass correlation coefficient being computed to measure interrater agreement. RESULTS: Regardless of tin prefiltration, PCD-CT with low (171.2 ± 10.3 HU) and intermediate radiation dose (134.7 ± 4.5 HU) provided less image noise than full-dose EID-CT (177.0 ± 14.2 HU; P < 0.001). Targeting matched image noise to 120 kVp EID-CT, mean dose reduction of 79.3% ± 3.9% could be realized in 120 kVp PCD-CT. Subjective image quality of PCD-CT was better than of EID-CT on each dose level ( P < 0.050). While no distinction was found between dose-matched PCD-CT with and without tin prefiltration ( P ≥ 0.928), Sn 150 kVp EID-CT provided better image quality than 120 kVp EID-CT at high and intermediate dose levels ( P > 0.050). The majority of low-dose EID-CT examinations were considered not diagnostic, whereas PCD-CT scans of the same dose level received satisfactory or better ratings. Interrater reliability was excellent (intraclass correlation coefficient 0.903). CONCLUSIONS: PCD-CT provides superior image quality and significant dose savings compared with EID-CT for ultra-high-resolution examinations of the temporal bone. Aiming for matched image noise, high-voltage scan protocols with tin prefiltration facilitate additional dose saving in EID-CT, whereas superior inherent denoising decreases the dose reduction potential of spectral shaping in PCD-CT.
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Fotones , Estaño , Humanos , Fantasmas de Imagen , Reproducibilidad de los Resultados , Tomografía Computarizada por Rayos X/métodos , Hueso TemporalRESUMEN
OBJECTIVES: In this study, we compared photon-counting detector computed tomography (PCD-CT) and energy-integrating detector computed tomography (EID-CT) for ultra-low-dose paranasal sinus examinations with employed tin prefiltration. The goal of our investigation was to define the most dose-effective scan protocols for diagnostic assessment of midface trauma, preoperative sinonasal anatomy, and acute rhinosinusitis. MATERIALS AND METHODS: Five cadaveric heads were examined with the standard-resolution scan mode of both CT systems using a tube potential of 100 kV and tin prefiltration for 7 dose-equivalent scan protocols (CTDI vol = 4.16-0.15 mGy) and 2 additional ultra-low-dose protocols exclusively feasible on the PCD-CT scanner (0.10 and 0.08 mGy). After applying comparable iterative reconstruction algorithms, image quality was subjectively assessed by 4 radiologists. The intraclass correlation coefficient was calculated to estimate the agreement among readers. Image noise was quantified in standardized regions of interest to establish an additional quantitative criterion of image quality. RESULTS: The most dose-effective scan protocols for diagnostic imaging of midface trauma (PCD-CT: 1.24 mGy; EID-CT: 2.05 mGy), preoperative sinonasal anatomy (PCD-CT: 0.20 mGy; EID-CT: 0.40 mGy), and acute rhinosinusitis (PCD-CT: 0.08 mGy; EID-CT: 0.15 mGy) required less radiation exposure on the PCD-CT system ( P < 0.050). Despite higher image noise, ultra-low-dose PCD-CT studies (0.08 and 0.10 mGy) were considered suitable for inflammation-focused imaging, offering lower-dose penalties than EID-CT studies. Interobserver reliability for subjective image quality was excellent (intraclass correlation coefficient, 0.90; 95% confidence interval, 0.88-0.93; P < 0.001). CONCLUSIONS: In paranasal sinus imaging with tin prefiltration, the PCD-CT allowed for superior image quality compared with high-end EID-CT. Assessment of paranasal sinuses with an ultra-low radiation exposure of 0.08 mGy was deemed adequate, suggesting substantial dose reduction potential for clinical routine, for example, in the diagnostic workup of patients with rhinosinusitis.
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Senos Paranasales , Estaño , Humanos , Senos Paranasales/diagnóstico por imagen , Fantasmas de Imagen , Fotones , Dosis de Radiación , Reproducibilidad de los Resultados , Tomografía Computarizada por Rayos X/métodosRESUMEN
PURPOSE: Cardiac MRI represents the gold standard to determine myocardial function. However, the current clinical standard protocol, a segmented Cartesian acquisition, is time-consuming and can lead to compromised image quality in the case of arrhythmia or dyspnea. In this article, a machine learning-based reconstruction of undersampled spiral k-space data is presented to enable free breathing real-time cardiac MRI with good image quality and short reconstruction times. METHODS: Data were acquired in free breathing with a 2D spiral trajectory corrected by the gradient system transfer function. Undersampled data were reconstructed by a variational network (VN), which was specifically adapted to the non-Cartesian sampling pattern. The network was trained with data from 11 subjects. Subsequently, the imaging technique was validated in 14 subjects by quantifying the difference to a segmented reference acquisition, an expert reader study, and by comparing derived volumes and functional parameters with values obtained using the current clinical gold standard. RESULTS: The scan time for the entire heart was below 1 min. The VN reconstructed data in about 0.9 s per image, which is considerably shorter than conventional model-based approaches. The VN furthermore performed better than a U-Net and not inferior to a low-rank plus sparse model in terms of achieved image quality. Functional parameters agreed, on average, with reference data. CONCLUSIONS: The proposed VN method enables real-time cardiac imaging with both high spatial and temporal resolution in free breathing and with short reconstruction time.