Noise assessment across two generations of iterative reconstruction algorithms of three manufacturers using bone reconstruction kernel

PurposeTo compare the noise-magnitude and noise-texture obtained using strong kernel across two generations of iterative reconstruction (IR) algorithms proposed by three manufacturers.Materials and methodsFive computed tomography (CT) systems equipped with two generations of IR algorithm (hybrid/statistical IR [H/SIR] or full/partial model-based IR [MBIR]) were compared. Acquisitions on Catphan 600 phantom were performed at 120 kV and three dose levels (CTDI_vol: 3, 7 and 12mGy). Raw data were reconstructed using standard “bone” kernel for filtered back projection and one iterative level of two generations of IR algorithms. Contrast-to-noise ratio (CNR) was computed using three regions of interest placed semi-automatically: two placed in the low-density polyethylene and Teflon inserts and another placed on the solid water. Noise power spectrum (NPS) was computed to assess the NPS-peak and noise-texture.ResultsCNR was significantly greater in MBIR compared to H/SIR algorithms for all CT systems (P < 0.01). CNR were improved on average from H/SIR to MBIR of 36 ± 14% [SD] (range: 24–57%) for GE-Healthcare, 109 ± 19 [SD] % (range: 89–139%) for Philips Healthcare and 42 ± 5 [SD] % (range: 36–47%) for Siemens Healthineers. The mean NPS peak decreased from H/SIR to MBIR by ?41 ± 6 [SD] % (range: ?47–?35%) for GE Healthcare, ?79 ± 3 [SD] % (range: ?82–?76%) for Philips Healthcare and ?52 ± 2 [SD] % (range: ?54–?51%) for Siemens Healthineers systems. NPS spatial frequencies were greater with MBIR than with H/SIR for Philips Healthcare (20 ± 2 [SD] %; range: 19–22%) and for Siemens Healthineers (9 ± 5 [SD] %; range: 4–14%) but lower for GE Healthcare (?17 ± 3 [SD] %; range: ?14–?20%).ConclusionUsing bone kernel with recent MBIR algorithms reduces the noise-magnitude for all CT systems assessed. Noise texture shifted towards high frequency for Siemens Healthineers and Philips Healthcare but the opposite for GE Healthcare.     

Impact of dose reduction and the use of an advanced model-based iterative reconstruction algorithm on spectral performance of a dual-source CT system: A task-based image quality assessment

PurposeTo assess the impact of dose reduction and the use of an advanced modeled iterative reconstruction algorithm (ADMIRE) on image quality in low-energy monochromatic images from a dual-source dual energy computed tomography CT (DSCT) platform.Materials and methodsAcquisitions on an image-quality phantom were performed using DSCT equipment with 100/Sn150 kVp for four dose levels (CTDI_vol: 20/11/8/5mGy). Raw data were reconstructed for six energy levels (40/50/60/70/80/100 keV) using filtered back projection and two levels of ADMIRE (A3/A5). Noise power spectrum (NPS) and task-based transfer function (TTF) were calculated on virtual monoenergetic images (VMIs). Detectability index (d′) was computed to model the detection task of two enhanced iodine lesions as function of keV.ResultsNoise-magnitude was significantly reduced between 40 to 70 keV by ?56 ± 0% (SD) (range: ?56%–?55%) with FBP; ?56 ± 0% (SD) (?56%–?56%) with A3; and ?57 ± 1% (SD) (range: ?57%–?56%) with A5. The average spatial frequency of the NPS peaked at 70 keV and decreased as ADMIRE level increased. TTF values at 50% were greatest at 40 keV and shifted towards lower frequencies as the keV increased. The detectability of both lesions increased with increasing dose level and ADMIRE level. For the simulated lesion with iodine at 2 mg/mL, d’ values peaked at 70 keV for all reconstruction types, except for A3 at 20 mGy and A5 at 11 and 20 mGy, where d’ peaked at 60 keV. For the other simulated lesion, d’ values were highest at 40 keV and decreased beyond.ConclusionAt low keV on VMIs, this study confirms that iterative reconstruction reduces the noise magnitude, improves the spatial resolution and increases the detectability of enhanced iodine lesions.     

Radiomics in the evaluation of lung nodules: Intrapatient concordance between full-dose and ultra-low-dose chest computed tomography

PurposeThe purpose of this study was to retrospectively evaluate the quantitative and qualitative intrapatient concordance of pulmonary nodule risk assessment by commercially available radiomics software between full-dose (FD) chest-CT and ultra-low-dose (ULD) chest CT.Materials and methodsBetween July 2013 and September 2015, 68 patients (52 men and16 women; mean age, 65.5 ± 10.6 [SD] years; range: 35–87 years) with lung nodules ≥ 5 mm and < 30 mm who underwent the same day FD chest CT (helical acquisition; 120 kV; automated tube current modulation) and ULD chest CT (helical acquisition; 135 kV; 10 mA fixed) were retrospectively included. Each nodule on each acquisition was assessed by a commercial radiomics software providing a similarity malignancy index (mSI), classifying it as “benign-like” (mSI < 0.1); “malignant-like” (mSI > 0.9) or “undetermined” (0.1 ≤ mSI ≤ 0.9). Intrapatient qualitative agreement was evaluated with weighted Cohen–Kappa test and quantitative agreement with intraclass correlation coefficient (ICC).ResultsNinety-nine lung nodules with a mean size of 9.14 ± 4.3 (SD) mm (range: 5–25 mm) in 68 patients (mean 1.46 nodule per patient; range: 1–5) were assessed; mean mSI was 0.429 ± 0.331 (SD) (range: 0.001–1) with FD chest CT (22/99 [22%] “benign-like”, 67/99 [68%] “undetermined” and 10/99 [10%] “malignant-like”) and mean mSI was 0.487 ± 0.344 (SD) (range: 0.002–1) with ULD chest CT (20/99 [20%] “benign-like”, 59/99 [60%] “undetermined” and 20/99 [20%] “malignant-like”). Qualitative and quantitative agreement of FD chest CT with ULD chest CT were “good” with Kappa value of 0.60 (95% CI: 0.46–0.74) and ICC of 0.82 (95% CI: 0.73–0.87), respectively.ConclusionA good agreement in malignancy similarity index can be obtained between ULD chest CT and FD chest CT using radiomics software. However, further studies must be done with more case material to confirm our results and elucidate the diagnostic capabilities of radiomics software using ULD chest CT for lung nodule characterization by comparison with FD chest CT.     

Discriminating between bronchiolar adenoma,adenocarcinoma in situ and minimally invasive adenocarcinoma of the lung with CT

PurposeTo identify computed tomography (CT) features that may help distinguish bronchiolar adenoma (BA) from lung adenocarcinomas in situ (AIS) and minimally invasive adenocarcinomas (MIA) among lung lesions presenting as ground-glass nodules (GGNs).Materials and methodsA total of 140 patients with GGNs confirmed by surgery and pathology, were reviewed retrospectively. There were 68 men and 72 women with a mean age of 64.3 ± 8.9 (SD) years (range: 31 – 85 years). The CT features of BA, AIS, and MIA were analyzed and compared. CT features, including percentage of solid component, maximum diameter of solid component, lesion density, location, margin, shape, pseudo-cavitation, calcification, ill-defined peripheral opacity, and air bronchogram, were analyzed using multivariate logistic regression and receiver operating characteristic curves.ResultsThere were 11/140 (7.9%) patients with BA (mean age, 67.7 ± 7.5 [SD]; range 45 – 77 years), 63/140 (45.0%) patients with AIS (mean age, 62.5 ± 8.6 [SD]; range 36 – 69 years) and 66/140 (47.1%) patients with MIA (mean age, 63.5 ± 7.9 [SD]; range 35 – 72 years). By comparison with AIS and MIA, significantly different CT features of BA included tumor size, solid component diameters, low CT attenuation of the ground-glass component, irregular shape, ill-defined peripheral opacity, pseudo-cavitation, and abnormal pulmonary vein. Ill-defined peripheral opacity (odds ratio, 1.060; 95% confidence interval [CI]: 1.020 – 1.380) and pseudo-cavitation (odds ratio, 1.236; 95% CI: 1.070 – 1.565) were variables independently associated with the diagnosis of BA.ConclusionCT provides morphological features that allow differentiating between BA and AIS-MIA among lung lesions presenting as GGNs.     

Optimization of image quality and accuracy of low iodine concentration quantification as function of dose level and reconstruction algorithm for abdominal imaging using dual-source CT: A phantom study

PurposeThe purpose of this study was to assess the impact of advanced modeled iterative reconstruction (ADMIRE) algorithm and dose levels on the accuracy of Hounsfield unit (HU) measurement, image noise and contrast-to-noise ratio (CNR) in virtual monochromatic images (VMIs) with low iodine concentrations, and the accuracy of iodine quantification.Materials and methodsA CT phantom was scanned with dual-source CT using abdomen-pelvis examination parameters at four dose levels: 5, 8, 11 and 20 mGy. Images were reconstructed using filtered-back projection (FBP) and ADMIRE levels 3 and 5 (A3-A5). HU accuracy was assessed calculating the root-mean-square deviation (RMSD_HU). Image noise and CNR were computed on VMIs at 40/50/60/70 keV for 4 iodine inserts with 0.5, 1, 2 and 5 mg/mL concentrations. Accuracy of iodine quantification was assessed by the RMSD_iodine and iodine bias (IB).ResultsThe RMSD_HU decreased significantly as the dose levels increased compared to 5 mGy, except for 8 mGy with A3 (P = 0.380) and with A5 level (P = 0.945). Noise increased by 63.0 ± 3.0 (standard deviation [SD])% from 20 mGy to 5 mGy. Noise decreased significantly by -53.8 ± 0.9 (SD) % with A5 compared to FBP. The CNR decreased by -43.1 ± 6.5 (SD)% from 20 mGy to 5 mGy. It increased using ADMIRE, and as the ADMIRE levels increased. The RMSD_iodine and IB decreased as the dose level increased, and this was similar for all reconstruction types.ConclusionADMIRE strongly improves image quality in VMIs and slightly improves HU accuracy but does not affect the accuracy of iodine quantification.     

Local recurrence following complete radiologic response in patients treated with transarterial chemoembolization for hepatocellular carcinoma

PurposeThe purpose of this study was to determine the local progression rate and identify factors that may predict local progression, in patients who achieve a complete response (CR) radiologically after undergoing transarterial chemoembolization (TACE) for hepatocellular carcinoma (HCC).Materials and methodsOne-hundred-forty-seven patients, who achieved CR of 224 HCCs after TACE, were retrospectively reviewed. There were 109 men and 38 women with a mean age of 61.6 ± 6.8 (SD) years (range: 45.4–86.9 years). Logistic mixed-effects and Cox regression models were used to evaluate associations between clinical factors and local progression.ResultsA total of 75 patients (75/147; 51%) and 99 (99/224,44.2%) lesions showed local progression at a median of 289.5 days (Q1: 125, Q3: 452; range: 51–2245 days). Pre-treatment, international normalization ratio (INR) (1.17 ± 0.15 [SD] vs. 1.25 ± 0.16 [SD]; P <0.001), model for end-stage liver disease (9.4 ± 2.6 [SD] vs. 10.6 ± 3.2 [SD]; P = 0.010) and Child-Pugh score (6 ± 1 [SD] vs. 6.4 ± 1.3 [SD]; P = 0.012) were significantly lower while albumin serum level (3.4 ± 0.62 [SD] vs. 3.22 ± 0.52 [SD]; P = 0.033) was significantly greater in those who showed local progression as compared to those who did not. In terms of local-recurrence free survival, the number of TACE treatments (hazard ratio [HR]: 2.05 [95% CI: 1.57–2.67]; P<0.001), INR (HR: 0.13 [95% CI: 0.03–0.61]; P = 0.010) and type of TACE (P = 0.003) were significant. Patients with local progression on any tumor did not differ from those who did in terms of overall survival (P = 0.072), however, were less likely to be transplanted (20/75, 26.7%) than those who did not (33/72; 36.1%) (P = 0.016).ConclusionA significant number of patients who achieve CR of HCC after TACE have local progression. This emphasizes the importance of long-term follow up.     

Increased signal intensity with delayed post contrast 3D-FLAIR MRI sequence using constant flip angle and long repetition time for inner ear evaluation

PurposeThe purpose of this study was to compare the degree of perilymphatic enhancement between 4 hour post-contrast constant flip angle three-dimensional fluid attenuated inversion recovery (3D-FLAIR) images obtained with short repetition time (TR) and those obtained with long TR.Materials and methodsThis single-center, prospective study included patients who underwent MRI of the inner ear with heavily T2-weighted sequence, 3D-FLAIR sequence with a “short” TR of 10,000 ms (s3D-FLAIR) and with a “long” TR of 16,000 ms (l3D-FLAIR). Signal intensity ratio (SIR) and contrast-to-noise ratio (CNR) obtained with s3D-FLAIR and l3D-FLAIR were quantitatively assessed using region of interest (ROI) method and compared. The morphology of the endolymphatic space on both sequences was also evaluated.ResultsFrom March 2020 to July 2020, 20 consecutive patients were enrolled (9 women and 11 men; mean age, 52.1 ± 14.5 [SD] years; age range: 29–75 years). On l3D-FLAIR images, mean SIR (21.1 ± 8.8 [SD]; range: 7.6–46.1) was significantly greater than that on s3D-FLAIR images (15.7 ± 6.7 [SD]; range: 5.9–33.4) (P < 0.01). On l3D-FLAIR images, mean CNR (17 ± 8.5 [SD]; range: 2–40) was significantly greater than that on s3D-FLAIR images (12 ± 6.3 [SD]; range: 3.2–29.8) (P < 0.01). Kappa value for inter-rater agreement for endolymphatic hydrops, vestibular atelectasis and perilymphatic fistula were 0.93 (95% CI: 0.74–1), 1 (95% CI: 0.85–1) and 1 (95% CI: 0.85–1) respectively.ConclusionThis study demonstrates that the sensitivity of 3D-FLAIR sequences to low concentration gadolinium in the perilymphatic space is improved by elongation of the TR, with SIR and CNR increased by +34.4% and +41.3% respectively.     

Diagnostic performance of ultra-low dose versus standard dose CT for non-traumatic abdominal emergencies

PurposeThe purpose of this study was to compare the diagnostic performance of ultra-low dose (ULD) to that of standard (STD) computed tomography (CT) for the diagnosis of non-traumatic abdominal emergencies using clinical follow-up as reference standard.Materials and methodsAll consecutive patients requiring emergency abdomen-pelvic CT examination from March 2017 to September 2017 were prospectively included. ULD and STD CTs were acquired after intravenous administration iodinated contrast medium (portal phase). CT acquisitions were performed at 125 mAs for STD and 55 mAs for ULD. Diagnostic performance was retrospectively evaluated on ULD and STD CTs using clinical follow-up as a reference diagnosis.ResultsA total of 308 CT examinations from 308 patients (145 men; mean age 59.1 ± 20.7 (SD) years; age range: 18–96 years) were included; among which 241/308 (78.2%) showed abnormal findings. The effective dose was significantly lower with the ULD protocol (1.55 ± 1.03 [SD] mSv) than with the STD (3.67 ± 2.56 [SD] mSv) (P < 0.001). Sensitivity was significantly lower for the ULD protocol (85.5% [95%CI: 80.4–89.4]) than for the STD (93.4% [95%CI: 89.4–95.9], P < 0.001) whereas specificities were similar (94.0% [95%CI: 85.1–98.0] vs. 95.5% [95%CI: 87.0–98.9], respectively). ULD sensitivity was equivalent to STD for bowel obstruction and colitis/diverticulitis (96.4% [95%CI: 87.0–99.6] and 86.5% [95%CI: 74.3–93.5] for ULD vs. 96.4% [95%CI: 87.0–99.6] and 88.5% [95%CI: 76.5–94.9] for STD, respectively) but lower for appendicitis, pyelonephritis, abscesses and renal colic (75.0% [95%CI: 57.6–86.9]; 77.3% [95%CI: 56.0–90.1]; 90.5% [95%CI: 69.6–98.4] and 85% [95%CI: 62.9–95.4] for ULD vs. 93.8% [95%CI: 78.6–99.2]; 95.5% [95%CI: 76.2–100.0]; 100.0% [95%CI: 81.4–100.0] and 100.0% [95%CI: 80.6–100.0] for STD, respectively). Sensitivities were significantly different between the two protocols only for appendicitis (P = 0.041).ConclusionIn an emergency context, for patients with non-traumatic abdominal emergencies, ULD-CT showed inferior diagnostic performance compared to STD-CT for most abdominal conditions except for bowel obstruction and colitis/diverticulitis detection.     

CT-guided biopsy of lung nodules with pleural contact: Comparison of two puncture routes

PurposeThe purpose of this study was to retrospectively compare two puncture routes (transpleural vs. transpulmonary) for computed tomography (CT) fluoroscopy-guided cutting needle biopsy of lung nodules with pleural contact.Patients and methodsA total of 102 patients (72 men; mean age, 71.1 ± 9.5 [SD] years) were included and 102 biopsies of 102 lung nodules (mean size, 16.7 ± 5.9 [SD] mm; range, 6.0–29.4 mm; mean length of pleural contact, 10.1 ± 4.2 [SD] mm; range, 2.8–19.6 mm) were analyzed. All procedures were classified as biopsies via the direct transpleural route or the transpulmonary route. The patient-, lesion-, and biopsy-related variables, diagnostic yields, and incidence of complications were compared between the two routes.ResultsBiopsy was performed via the direct transpleural route (n = 59; 57.8%) and transpulmonary route (n = 43; 42.2%). In the transpulmonary route group, the mean distance of the intrapulmonary pathway was 17.7 ± 9.4 [SD] mm (range: 4.1–47.6 mm; P < 0.001) and the introducer needle trajectory angle of < 45° was significantly observed (8.5% [5/59] vs. 60.5% [26/43]; P < 0.001). There was no significant difference in diagnostic accuracy between the direct transpleural and transpulmonary routes (93.2% [55/59] vs. 90.7% [39/43]; P = 0.718). The frequencies of all complications (64.4% [38/59] vs. 97.7% [42/43]; P < 0.001), pneumothorax (33.9% [20/59] vs. 65.1% [28/43]; P = 0.003), pneumothorax with chest tube placement (3.4% [2/59] vs. 18.6% [8/43]; P = 0.016), and pulmonary hemorrhage (47.5% [28/59] vs. 76.7% [33/43]; P = 0.004) were significantly lower in the direct transpleural group.ConclusionDirect transpleural route is recommended for CT fluoroscopy-guided biopsy of lung nodules with pleural contact because it is safer and yields similar diagnostic accuracy than transpulmonary route.     

Metal artifact reduction for intracranial projectiles on post mortem computed tomography

PurposeTo compare the image quality of cranial post-mortem computed tomography (CT) obtained with and without projection-based single-energy metal artifact reduction (SEMAR) in cadavers with intracranial metallic ballistic projectiles.Materials and methodsFrom January 2017 to January 2018, cadavers with ballistic projectile head wounds with metal fragments and without massive head destruction were investigated using post-mortem CT. All subjects underwent CT using a conventional iterative reconstruction (IR) and SEMAR. To evaluate the impact of metallic artifacts, the total intracranial area (TA), non-interpretable zone (NIZ), disturbed interpretation zone (DZ), and artifact total surface (ATS) were delineated. Two independent readers identified extra-axial hemorrhage (EAH) and subarachnoid hemorrhage (SAH). Autopsy reports were used as the standard of reference.ResultsEleven corpses (10 males, 1 female; mean age, 62.8 ± 17.9 [SD] years) were evaluated. SEMAR showed a significant decrease in the ATS ratio with respect to conventional IR (72.1 ± 26.1 [SD] % [range: 26.8-99.1] vs. 86.4 ± 17.8 [SD] % [range: 37.2-100]; P < 0.001) and NIZ/TA ratios (11.6 ± 8.26% [range: 0.95–33.4] versus 42.5 ± 30.5% [range: 3.86–100]; P < 0.001). The interobserver reproducibility in diagnosing EAH and SAH was excellent with conventional IR (0.82) and good with SEMAR (0.75). SEMAR reduced uncertain diagnoses of EAH in 7 subjects for Reader 1 and in 6 for Reader 2, but did not influence the diagnosis of SAH for either reader.ConclusionSEMAR reduces the influence of metallic artifacts and increases the confidence with which the diagnosis of EAH can be made on post-mortem CT.     

Lung shunt fraction calculations before Y-90 transarterial radioembolization: Comparison of accuracy and clinical significance of planar scintigraphy and SPECT/CT

PurposeTo determine the accuracy and clinical significance of planar scintigraphy lung shunt fraction (PLSF) and single-photon emission computerized tomography (SPECT) computed tomography (CT) lung shunt fraction (SLSF) before Y-90 transarterial radioembolization.Materials and methodsSeventy patients (46 men, 24 women; mean age, 64 ± 9.5 [SD] years) who underwent 83 treatments with Y-90 transarterial radioembolization for primary or secondary malignancies of the liver with a PLSF ≥ 7.5% were retrospectively evaluated. The patients mapping technetium 99 m (Tc-99 m) macroaggregated albumin (MAA) PLSF and SLSF were calculated and compared to the post Y-90 delivery SLSF. A model using modern dose thresholds was created to identify patients who would require dose reduction due to a lung dose ≥ 30 Gy, with patients who required >50% dose reduction considered to be delivery cancelations.ResultsA significant difference was found between mean PLSF (14.7 ± 11.6 [SD]%; range: 7.5–84.1%) and mean SLSF (8.7 ± 8.5 [SD]%; range: 1.7–73.5) (P < 0.001). The mean realized LSF (7.1 ± 3 [SD]%; range:1.5–17.6) was significantly less than the PLSF (P <0.001) but not the SLSF (P = 0.07). PLSF significantly overestimated the realized LSF by more than the SLSF (8.5 ± 5.3 [SD] % [range: -0.1–21.7] vs. 0.8 ± 3.6 [SD] % [range: -5–13.2], respectively) (P < 0.001). Based on the clinical significance model, 20 patients (20/83, 24.1%) would have required dose reduction or cancelation when using PLSF but would not require even a dose reduction when using the SLSF. Significantly more deliveries would have been be canceled if PLSF was used as compared to SLSF (22/83 [26.5%] vs. 6/83 [7.2%], respectively) (P < 0.001).ConclusionSLSF is significantly more accurate at predicting realized LSF than PLSF and this difference is of clinical significance in a number of patients with a PLSF ≥ 7.5%.     

Artificial intelligence solution to classify pulmonary nodules on CT

PurposeThe purpose of this study was to create an algorithm to detect and classify pulmonary nodules in two categories based on their volume greater than 100 mm³ or not, using machine learning and deep learning techniques.Materials and methodThe dataset used to train the model was provided by the organization team of the SFR (French Radiological Society) Data Challenge 2019. An asynchronous and parallel 3-stages pipeline was developed to process all the data (a data “pre-processing” stage; a “nodule detection” stage; a “classifier” stage). Lung segmentation was achieved using 3D U-NET algorithm; nodule detection was done using 3D Retina-UNET and classifier stage with a support vector machine algorithm on selected features. Performances were assessed using area under receiver operating characteristics curve (AUROC).ResultsThe pipeline showed good performance for pathological nodule detection and patient diagnosis. With the preparation dataset, an AUROC of 0.9058 (95% confidence interval [CI]: 0.8746–0.9362) was obtained, 87% yielding accuracy (95% CI: 84.83%–91.03%) for the “nodule detection” stage, corresponding to 86% specificity (95% CI: 82%–92%) and 89% sensitivity (95% CI: 84.83%–91.03%).ConclusionA fully functional pipeline using 3D U-NET, 3D Retina-UNET and classifier stage with a support vector machine algorithm was developed, resulting in high capabilities for pulmonary nodule classification.     

CT fluoroscopy-guided biopsy of pulmonary lesions contacting the interlobar fissure: An analysis of 72 biopsies

PurposeThe purpose of this study was to evaluate retrospectively the safety and diagnostic yield of computed tomography (CT) fluoroscopy-guided biopsy for pulmonary lesions with interlobar fissure contact.Materials and methodsSeventy-two lesions showing interlobar fissure contact (mean size, 15.2 ± 5.3 [SD] mm [range: 5.3–27.0 mm]; mean length of interlobar fissure contact, 8.9 ± 3.6 [SD] mm [range: 2.6–17.5 mm] in 72 patients (33 men, 39 women; mean age, 69.7 ± 10.3 [SD] years; age range: 37–91 years) were evaluated. Multiple variables were assessed to determine the risk factors for diagnostic failure and pneumothorax. Additionally, these variables were compared between these 72 lesions and randomly selected controls (i.e., non-contact lesions).ResultsAll biopsies were technically successful using the transfissural (n = 14) or conventional routes (the route into the lung lobe with the target) with (n = 35) or without (n = 23) possible risk of needle insertion into the interlobar fissure after penetrating the target lesion. Sixty-eight (94.4%) procedures succeeded diagnostically and four (5.6%) failed. There were 27 grade I pneumothorax (37.5%), one (1.4%) grade II bleeding, and five (6.9%) grade IIIa pneumothorax requiring chest tube placement. Groups with and without pneumothorax did not differ significantly in patient-, lesion-, or procedure-related variables. Diagnostic yields and pneumothorax occurrence showed no significant differences between lesions with interlobar fissure contact and controls.ConclusionCT fluoroscopy-guided biopsy of pulmonary lesions with interlobar fissure contact is a safe procedure with a high diagnostic yield. Furthermore, because of potential complications, the transfissural route should be used only when a safer route is not possible.     

Differences in right ventricular-pulmonary vascular coupling and clinical indices between repaired standard tetralogy of Fallot and repaired tetralogy of Fallot with pulmonary atresia

PurposeThe purpose of this study was to compare ventricular vascular coupling ratio (VVCR) between patients with repaired standard tetralogy of Fallot (TOF) and those with repaired TOF-pulmonary atresia (TOF-PA) using cardiovascular magnetic resonance (CMR).Materials and methodsPatients with repaired TOF aged > 6 years were prospectively enrolled for same day CMR, echocardiography, and exercise stress test following a standardized protocol. Sanz's method was used to calculate VVCR as right ventricle (RV) end-systolic volume/pulmonary artery stroke volume. Regression analysis was used to examine associations with exercise test parameters, New York Heart Association (NYHA) class, RV size and biventricular systolic function.ResultsA total of 248 subjects were included; of these 222 had repaired TOF (group I, 129 males; mean age, 15.9 ± 4.7 [SD] years [range: 8–29 years]) and 26 had repaired TOF-PA (group II, 14 males; mean age, 17.0 ± 6.3 [SD] years [range: 8–29 years]). Mean VVCR for all subjects was 1.54 ± 0.64 [SD] (range: 0.43–3.80). Mean VVCR was significantly greater in the TOF-PA group (1.81 ± 0.75 [SD]; range: 0.78–3.20) than in the standard TOF group (1.51 ± 0.72 [SD]; range: 0.43–3.80) (P = 0.03). VVCR was greater in the 68 NYHA class II subjects (1.79 ± 0.66 [SD]; range: 0.75–3.26) compared to the 179 NYHA class I subjects (1.46 ± 0.61 [SD]; range: 0.43–3.80) (P < 0.001).ConclusionNon-invasive determination of VVCR using CMR is feasible in children and adolescents. VVCR showed association with NYHA class, and was worse in subjects with repaired TOF-PA compared to those with repaired standard TOF. VVCR shows promise as an indicator of pulmonary artery compliance and cardiovascular performance in this cohort.     

Accuracy of a CT density threshold enhancement to identify pancreatic parenchyma necrosis in acute pancreatitis during the first week

PurposeThe purpose of this study was to identify attenuation threshold value on computed tomography (CT) that allowed discriminating between interstitial edematous pancreatitis (IEP) and necrotizing pancreatitis (NP) in patients with acute pancreatitis during the first week of the disease and evaluate interobserver reproducibility for the diagnosis of acute pancreatitis category.Materials and methodsPatients with acute pancreatitis who underwent CT examination of the abdomen between March 2015 and December 2019 were retrospectively included. Actual diagnosis of IEP or NP was based on final clinical report, follow-up evaluation, and complications. Six regions of interest were manually placed in the pancreatic gland and peripancreatic fat, and differences in CT attenuation values before contrast injection and during the portal venous phase of enhancement were computed. Performance in the diagnosis of AP category was evaluated using receiver operating characteristic analysis. Interobserver agreement was estimated by the intraclass correlation coefficient (ICC) and Bland Altman analysis was used to estimate reproducibility between pairs of observers.ResultsSixty-six patients with NP (46 men, 20 women; mean age, 55 ± 17 [SD] years; age range: 20-89 years) and 70 patients with IEP (39 men, 31 women; mean age, 54 ± 18 [SD] years; age range: 21–87 years) were included. An enhancement value less than 30 Hounsfield units (HU) in the pancreatic gland during the portal phase compared to non-contrast phase, yielded 90.9% sensitivity (60/66; 95% CI: 81.3–96.6), 94.3% specificity (66/70; 95% CI: 86.0–98.4) and an area under curve of 0.958 (95% CI: 0.919–0.996) for the diagnosis of NP versus IEP. Interobserver reproducibility for pancreas enhancement was good using Bland Altman plot and ICC was excellent for pancreatic gland analysis (ICC 0.978; 95% CI: 0.961–0.988) but poor or moderate (ICC ≤0.634) regarding peripancreatic fat necrosis.ConclusionBy using a pancreas enhancement threshold value of 30 HU, CT is accurate and reproducible for the diagnosis of NP during the first week of the disease.     

Computed tomography features of acinar cell carcinoma of the pancreas

PurposeTo report the computed tomography (CT) features of pancreatic acinar cell carcinoma (ACC) and identify CT features that may help discriminate between pancreatic ACC and pancreatic ductal adenocarcinoma (PDA).Materials and methodsThe CT examinations of 20 patients (13 men, 7 women; mean age, 66.5 ± 10.7 [SD] years; range: 51–88 years) with 20 histopathologically proven pancreatic ACC were reviewed. CT images were analyzed qualitatively and quantitatively and compared to those obtained in 20 patients with PDA. Comparisons were performed using univariate analysis with a conditional logistic regression model.ResultsPancreatic ACC presented as an enhancing (20/20; 100%), oval (15/20; 75%), well-delineated (14/20; 70%) and purely solid (13/20; 65%) pancreatic mass with a mean diameter of 52.6 ± 28.0 (SD) mm (range: 24–120 mm) in association with visible lymph nodes (14/20; 70%). At univariate analysis, well-defined margins (Odds ratio [OR], 7.00; P = 0.005), nondilated bile ducts (OR, 9.00; P = 0.007), visible lymph nodes (OR, 4.33; P = 0.028) and adjacent organ involvement (OR, 5.67; P = 0.02) were the most discriminating CT features to differentiate pancreatic ACC from PDA. When present, lymph nodes were larger in patients with pancreatic ACC (14 ± 4.8 [SD]; range: 7–25 mm) than in those with PDA (8.8 ± 4.1 [SD]; range: 5–15 mm) (P = 0.039).ConclusionOn CT, pancreatic ACC presents as an enhancing, predominantly oval and purely solid pancreatic mass that most frequently present with no bile duct dilatation, no visible lymph nodes, no adjacent organ involvement and larger visible lymph nodes compared to PDA.     

Ultrasonographic anatomy of the long thoracic nerve: A reappraisal using high frequency (24-MHz) probe

PurposeThe purpose of this study was to analyze the potential of ultrasound with a high frequency probe (24-MHz) in the assessment of the long thoracic nerve (LTN) and describe ultrasonographic landmarks that can be used for standardization.Material and methodsUltrasonography analysis of the LTN was done on 2 LTNs in a cadaver specimen and then on 30 LTNs in 15 healthy volunteers (12 men, 3 women; mean age, 28.8 ± 3.8 [SD] years; age range: 24–39 years) by two independent radiologists (R1 and R2) using a 24-MHz probe. Interrater agreement was assessed using Kappa test (K) and intraclass correlation coefficient (ICC).ResultsIn the cadaver, dissection confirmed that the India ink was injected near the LTN in the middle scalene muscle. In volunteers, visibility of the LTN above the clavicle was highly reproducible for the branches arising from C5 (R1: 87% [26/30]; R2: 90% [27/30]; K = 0.83) and from C6 (R1: 100% [30/30]; R2: 97% [29/30]; K = 0.94). Where the nerve emerged from the middle scalene muscle, the mean diameter was 0.85 ± 0.24 (SD) mm (range: 0.4–1.6 mm) for R1 and 0.9 ± 0.23 (SD) mm (range: 0.4–1.7 mm) for R2 (ICC: 0.96; 95% CI: 0.92–0.98%). Along the thoracic wall, where LTN run along the lateral thoracic artery, the mean diameter was 0.83 ± 0.19 (SD) mm (range: 0.5–1.27 mm) for R1 and 0.89 ± 0.21 (SD) mm (range: 0.6–1.2 mm) for R2 (ICC: 0.86; 95% CI: 0.72–0.93%).ConclusionThe LTN can be analyzed with ultrasound using high-frequency probe by using the C5 and C6 roots, the middle scalene muscle above the clavicle and the lateral thoracic artery on the chest wall as landmarks.     

多排螺旋CT非螺旋低剂量扫描筛查肺结节

目的探讨4排螺旋CT非螺旋低剂量扫描方式在肺结节诊断中的价值。方法对30例胸片可疑肺结节患者分别行螺旋低剂量和非螺旋低剂量扫描。采用Toshiba 4排多层螺旋CT（Asteion 4）扫描机。螺旋扫描采用预设35.5 mAs,床进20 mm/圈（即螺距1）,0.75 s/圈,非螺旋扫描预设24 mAs,床进20 mm/圈（层厚=层距）,0.48 s/圈,其他扫描参数相同：120 kV,准直0.5×4,DFOV 300 mm,重建层厚5mm。根据出现伪影程度及是否分辨出肺结节来评价CT图像质量,对肺结节进行简单计数。比较两者发现肺结节的差异及有效放射剂量的差异。结果两种扫描方式检查30例患者均为阳性,发现各种肺结节都是108个。非螺旋扫描的有效放射剂量低于螺旋扫描方式（P〈0.001）。结论非螺旋方式扫描与螺旋方式扫描在胸部低剂量检查中对于肺内病灶的发现及诊断无统计学差异,扫描剂量相对更低的非螺旋方式扫描应用于胸部疾病的诊断及筛查是可行的。     

MR imaging features and long-term evolution of benign focal liver lesions in Budd-Chiari syndrome and Fontan-associated liver disease

PurposeTo compare the magnetic resonance imaging (MRI) features of benign liver lesions developed on Budd-Chiari syndrome (BCS) with those on Fontan-associated liver disease (FALD) and to describe their long-term progression.Materials and methodsPatients with BCS or FALD who underwent MRI between 2010 and 2020 were retrospectively included. MRI features of nodules (≥ 5 mm) at baseline and at final follow-up were reviewed. The final diagnosis of benign lesion was based on a combination of clinical and biological data and findings at follow-up MRI examination.ResultsTwo-hundred and thirty benign liver lesions in 39 patients with BCS (10 men, 29 women; mean age, 36 ± 11 [SD] years; age range: 15–66 years) and 84 benign lesions in 14 patients with FALD (2 men, 12 women; mean age, 31 ± 10 [SD] years; age range: 20–48 years) were evaluated. On baseline MRI, BCS nodules were more frequently hyperintense on T1-weighted (183/230, 80%) and hypointense on T2-weighted (142/230; 62%) images, while FALD nodules were usually isointense on both T1- (70/84; 83%) and T2-weighted (64/84; 76%) images (all P< 0.01). Most lesions showed arterial phase hyperenhancement (222/230 [97%] vs. 80/84 [95%] in BCS and FALD, respectively; P = 0.28) but wash-out was more common in BCS (64/230 [28%] vs. 9/84 [11%]; P < 0.01). At follow-up, changes were more frequent in BCS nodules with more frequent disappearance (P < 0.01), changes in size, signal intensity on T2-weighted, portal, and delayed phase, and in the depiction of washout and capsule (all P ≤ 0.03).ConclusionMRI features of benign lesions are different at diagnosis and during the course of the disease between BCS and FALD. Changes in size and MRI features are more frequent in benign lesions developed in BCS.