Photon-counting CT for diagnosis of acute pulmonary embolism: potential for contrast medium and radiation dose reduction

Abstract

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.

Multimodality imaging of acute and chronic pulmonary thromboembolic disease

“…In particular, the recent introduction of the first clinical photon counting CT (PCCT) allowed images to be obtained with a higher spatial resolution and preserved radiation dose efficiency compared with conventional CT systems with energy-integrating detectors. Moreover, PCCT could also allow performance of scans with a reduced CM administration as well as a reduced effective dose, while maintaining a good to optimal image quality [ 48 ].…”

The CT revolution: the role of PIOPED II in establishing CT pulmonary angiography as the reference standard for pulmonary embolism diagnosis

“…These values as likely to increase in the coming years, as wider availability of artificial intelligence software may enhance radiologists' sensitivity in detecting pulmonary emboli, and photon-counting detectors may further enhance CTPA performance while lowering contrast-medium volume and radiation dose [ 26 , 27 ].…”

Reduction of Iodinated Contrast Medium Dose in Computed Tomography Pulmonary Angiography and its Impact on Image Quality: A Narrative Review

“…These capabilities are particularly valuable when fast image acquisition and motion artifact reduction are essential, such as in CTPA [33][34][35][36]. Novel technological advancements in CT hardware, such as photon-counting detectors are promising, allowing for significant reduction of ICM and radiation dose in the diagnosis of PE, while maintaining good to excellent image quality [34,37].…”

“…PCD-CTPA offers substantial advantages in terms of rapid image acquisition, radiation and ICM dose reduction and advanced imaging methods. The virtual mono energetic imaging on PCD-CT scanner offers the potential of ICM dose minimization and allows good to excellent image quality compared to a standard DE-CTPA protocol [37]. DE-CTPA presents another approach to reduce ICM dose and iodine load.…”