Sonja Kandel

Objective: Quantify the outcomes following pneumothorax aspiration and influence upon chest drain insertion. Methods: This was a retrospective cohort study of patients who underwent aspiration for the treatment of a pneumothorax following a CT percutaneous transthoracic lung biopsy (CT-PTLB) from January 1, 2010 to October 1, 2020 at a tertiary center. Patient, lesion and procedural factors associated with chest drain insertion were assessed with univariate and multivariate analyses. Results: A total of 102 patients underwent aspiration for a pneumothorax following CT-PTLB. Overall, 81 patients (79.4%) had a successful pneumothorax aspiration and were discharged home on the same day. In 21 patients (20.6%), the pneumothorax continued to increase post-aspiration and required chest drain insertion with hospital admission. Significant risk factors requiring chest drain insertion included upper/middle lobe biopsy location [odds ratio (OR) 6.46; 95% CI 1.77–23.65, p = 0.003], supine biopsy position (OR 7.06; 95% CI 2.24–22.21, p < 0.001), emphysema (OR 3.13; 95% CI 1.10–8.87, p = 0.028), greater needle depth ≥2 cm (OR 4.00; 95% CI 1.44–11.07, p = 0.005) and a larger pneumothorax (axial depth ≥3 cm) (OR 16.00; 95% CI 4.76–53.83, p < 0.001). On multivariate analysis, larger pneumothorax size and supine position during biopsy remained significant for chest drain insertion. Aspiration of a larger pneumothorax (radial depths ≥3 cm and ≥4 cm) had a 50% rate of success. Aspiration of a smaller pneumothorax (radial depth 2–3 cm and 80%). Advances in knowledge: Aspiration of pneumothoraces up to 3 cm was often associated with avoiding chest drain insertion and allowing for earlier discharge.

To evaluate a contiguous helical CT protocol with two different target noise levels in chest/abdomen/pelvis CT.

The purpose of this research was to evaluate respiratory gated CT of the lung in patients with COPD for analysis of parenchymal characteristics who were potential candidates for volume reduction surgery. Eleven patients with clinically known emphysematous disease underwent a respiratory gated, free-breathing 64-multislice-CT (Aquilion 64, Toshiba). Retrospective image reconstruction was performed similar to cardiac CT at every 10% of the respiratory loop, resulting in 10 complete volumetric datasets at 10 equidistant time points. All images were transferred onto a PC for calculation of the total lung volume, emphysema volume, emphysema index, and mean lung density. Complete datasets could be successfully reconstructed in all patients. The mean lung volume increased from 6.9 L to 7.5 L over the respiratory cycle. Emphysema volume increased from 1.6 L to 2.0 L and emphysema index from 22.6% to 26.5% from expiration to inspiration. In conclusion, respiratory gated chest 4D-CT allows for combined morphologic and functional image analysis, which can provide new insight into functional impairment and individual treatment planning.

Objectives To compare two scanning protocols (free breathing versus breath-hold) for perfusion imaging using dynamic volume computed tomography (CT) and to evaluate their effects on image registration. Material and methods Forty patients underwent dynamic volume CT for pancreatic perfusion analysis and were randomly assigned to either a shallow-breathing (I) or breath-hold (II) group. Both dynamic CT protocols consisted of 17 low-dose volumetric scans. Rigid image registration was performed by using the volume with highest aortic attenuation as reference. All other volumes were visually matched with the pancreatic lesion serving as the volumetric region of interest. The overall demand for post-processing per patient was calculated as the median of three-dimensional vector lengths of all volumes in relation to the relative patient origin. The number of volumes not requiring registration was recorded per group. Results Registration mismatch for groups I and II was 2.61 mm (SD, 1.57) and 4.95 mm (SD, 2.71), respectively (P < 0.005). Twenty-eight volumes in group I (8.2%) and 47 volumes in group II (14.1%) did not require manual registration (P = 0.014). Conclusion Shallow breathing during dynamic volume CT scanning reduces the overall demand for motion correction and thus may be beneficial in perfusion imaging of the pancreas Main Messages • Shallow breathing during perfusion CT scanning reduces the overall demand for motion correction. • Shallow breathing may be beneficial in perfusion imaging of the pancreas. • Image registration is crucial for CT perfusion imaging.

Ziele: Die Auswirkung der Kontrastmittelboluslänge auf die Berechnung von Perfusionwerten wurde basierend auf die Maximum-Slope-Technik und mithilfe eines Schweinemodels analysiert. Methode: 20 gesunde Schweine (Gewicht 63–77kg) erhielten ein dynamisches Volumen 320-Schicht-CT der Nieren in Atemstillstand. In alle Schweine wurde vor der CT-Untersuchung eine Flusssonde um die rechte Nierenarterie chirurgisch implantiert. Zwei identische dynamische CT-Serien der Nieren (Serie I und II) wurden über einen Zeitraum von 3 Minuten akquiriert. In der ersten Untersuchung erstreckte sich der venöse Bolus über 3.8 Sekunden, in der zweiten Untersuchung über 11.5 Sekunden. Die Menge des Kontrastmittels wurde gewichtsadaptiert für jedes Schwein berechnet. Für beide Untersuchungen wurden Perfusionswerte (ml-1) der rechten Niere mittels Maximum-Slope-Technik kalkuliert und mit dem Referenzstandard der Flussonde verglichen. Ergebnis: Der Mittelwert des Referenzstandard und der CT Perfusionswerte (min-1) betrugen für Serie I/II 1.95/2.02 (p=0.22) und 2.03/1.93 (p=0.12). In der linearen Regression korrelierten die CT Perfusionswerte in Serie I und II sehr gut mit dem Referenzstandard (r2=0.96 und r2=0.92). Im Durchschnitt hat der kurze Bolus den Referenzwert um 4.3% überschätzt, der lange Bolus unterschätzte den Referenzwert um 4,4%. Schlussfolgerung: CT Perfusionswerte werden durch die Länge des Kontrastmittelbolus beeinflusst. Daher sollte die Länge des Kontrastmittelbolus in Verlaufsuntersuchungen immer gleich bleiben, um Fehlinterpretationen von Perfusionswerten zu vermeiden. Keywords: Perfusion, CT, Kontrastmittelbolus Korrespondierender Autor: Kandel S University Health Network, Medical Imaging, University Street, M5G 2N2, Toronto E-Mail: sonja.kandel@uhn.ca

To compare tube current adaptation based on 3 body mass index (BMI) categories versus anterior-posterior chest diameter (APD) for radiation dose optimisation in patients undergoing dynamic volume cardiac CT. Two cardiac imaging centres participated in the study. 20 patients underwent a prospectively triggered 320-slice single beat cardiac CT using the X-ray tube current [mA] manually adjusted to the patient’s BMI (group I). In 20 subsequent patients, the tube current was adapted according to the patient’s APD (group II). All other parameters were kept constant. Image noise was defined as the standard deviation of attenuation values and measured using a ROI in the descending aorta. Variation in image noise was statistically compared between both patient groups. Average and standard deviation of pixel noise were 29.1 HU and 14.8 HU in group I and 28.0 HU and 4.2 HU in group II. Inter-individual variation of pixel noise was significantly lower in group II compared to group I (p < 0.0001). Tube current adaptation based on APD is superior to stepwise adaptation based on BMI for optimising radiation dose in dynamic volume cardiac CT and therefore limits unnecessary radiation dose while ensuring diagnostic image quality in patients with diverse body habitus.

Purpose: We sought to compare the performance of 3 computer-aided detection (CAD) polyp algorithms in computed tomography colonography (CTC) with fecal tagging. Methods: CTC data sets of 33 patients were retrospectively analysed by 3 different CAD systems: system 1, MedicSight; system 2, Colon CAD; and system 3, Polyp Enhanced View. The polyp database comprised 53 lesions, including 6 cases of colorectal cancer, and was established by consensus reading and comparison with colonoscopy. Lesions ranged from 6-40 mm, with 25 lesions larger than 10 mm in size. Detection and false-positive (FP) rates were calculated. Results: CAD systems 1 and 2 could be set to have varying sensitivities with higher FP rates for higher sensitivity levels. Sensitivities for system 1 ranged from 73%–94% for all lesions (78%–100% for lesions ≥10 mm) and, for system 2, from 64%–94% (78%–100% for lesions ≥10 mm). System 3 reached an overall sensitivity of 76% (100% for lesions ≥10 mm). The mean FP rate per patient ranged from 8–32 for system 1, from 1–8 for system 2, and was 5 for system 3. At the highest sensitivity level for all polyps (94%), system 2 showed a statistically significant lower FP rate compared with system 1 ( P = .001). When analysing lesions ≥10 mm, system 3 had significantly fewer FPs than systems 1 and 2 ( P < .012). Conclusions: Standalone CTC-CAD analysis in the selected patient collective showed the 3 systems tested to have a variable but overall promising performance with respect to sensitivity and the FP rate.