Research in diagnostic and interventional imaging最新文献

Objective

Screening ultrasound for hepatocellular carcinoma (HCC) identifies lesions which require further characterization by a contrast-enhanced exam to non-invasively diagnose HCC. While ultrasound is recommended in screening, some HCC can be occult on grayscale imaging. The purpose of this study was to determine if the addition of ultrasound contrast (sulfahexafluoride) to screening ultrasound for HCC can identify more HCC lesions than grayscale sonographic imaging alone.

Methods

All HCC screening ultrasounds that also had contrast were evaluated in this retrospective study. Patients with a focal lesion seen only after administration of contrast (OAC) were noted, as well as any follow-up imaging or pathology results. Additional variables collected included patient demographics, cirrhosis type, and laboratory values.

Results

230 unique patients were included, of which 160 had imaging or pathology follow-up. 18 of these patients had an OAC lesion, of which 17 had follow-up. Among these OACs, there was one LIRADS M lesion (1/18, 5.6 %) and one bland portal vein thrombus identified, which were both confirmed on follow-up imaging. All LIRADS 4 OAC lesions were downgraded. No additional HCC were identified on follow-up imaging or pathology of these patients.

Conclusion

Addition of contrast to screening ultrasound did identify additional lesions, portal vein thrombus, and high grade malignancy. However, as the incidence of OAC lesions was low (7.8 %, 18/230) and most of the lesions were not malignant, addition of post contrast sweeps through the liver is of low value in the low to medium at-risk cirrhotic population in identifying occult HCC.

Purpose

In lung cancer patients, the distinction between synchronous primary lung cancer and intrapulmonary metastasis can be challenging. The intensity of FDG uptake in pulmonary lesions has been shown to be potentially useful in classifying synchronous lung cancer. The aim of this retrospective study is to investigate the effectiveness of FDG uptake in differentiating metastases from synchronous primary lesions in the setting of lung cancer.

Methods

Consecutive patients with primary lung cancer with two or more malignant lung lesions referred for (¹⁸F)-FDG PET-CT imaging between 2010 and 2019 were reviewed and classified into synchronous and metastasis groups. Lesional maximum standardized uptake values (SUV_max), relative differences in SUV_max and SUV_max ratios were calculated and compared using receiver operating characteristic (ROC) curve analysis. Intra-group correlation in SUV_max between lesion pairs was examined using Pearson's and Spearman's correlation analysis.

Results

94 patients were included for analysis, divided into synchronous (n = 62; 68 lesion pairs) and metastasis (n = 32; 33 lesion pairs) groups. The correlation of FDG uptake between lesions in the metastasis group was strong (r = 0.81). A significant difference in mean relative difference in SUV_max (synchronous: 0.50±0.23 metastasis: 0.34±0.17, p = 0.001) and mean SUV_max ratio (synchronous: 2.6 ± 1.7 metastasis: 1.7 ± 0.6, p < 0.001) was observed. ROC analysis revealed a fair AUC (0.71–0.72) for these parameters, with an associated sensitivity of 59 % and specificity of 82 % at optimal cut-off values.

Conclusion

Differences in FDG uptake intensity among multiple synchronously presenting malignant nodules may be helpful to distinguish second primary lung tumours from metastatic spread.

Background

Recent studies have shown that an increased number of axillary lymph node metastases is associated with non-visualized lymph nodes. The purpose of the study was to retrospectively analyze the incidence and characteristics of non-visualized sentinel lymph nodes (SLNs) in nodal metastases in breast cancer patients.

Methods

Consecutive women with breast cancer referred for lymphoscintigraphy from January 2021 to November 2022 were reviewed retrospectively. Findings from resected SLNs and non-SLNs and relevant histopathology were collected and analyzed.

Results

500 patients diagnosed with breast cancer were reviewed, excluding 93 patients due to neoadjuvant therapy, DCIS, recurrence, or incomplete clinical documentation. Of the 407 remaining patients, 108 patients were positive for axillary lymph node metastases (24 %) and were the focus of the study. Of this patient cohort, 38 patients (35 %) had non-detected SLNs by intraoperative gamma probe and 43 (40 %) had non-visualized SLNs by lymphoscintigraphy. There was statistically significant difference in primary tumor size (39.8 mm versus 28.9 mm), number of resected (6.9 ± 4.4 versus 4.6 ± 2.4) and positive (3.4 ± 2.2 versus 1.6 ± 1.3) lymph nodes, size (13.8 ± 6.1 mm versus 8.1 ± 4.5 mm), tumor grade and tumor stage between the SLN non-visualized and visualized groups. The multivariate logistic regression analysis showed that only lymph node size and number of lymph nodes resected were independent factors associated with SLN non-visualization.

Conclusions

We reported a high non-visualization rate of SLN in breast cancer patients with pathology-proven positive axillary nodes. The causes of the SLN non-visualization are not well understood and warrants further exploration.

Purpose

To determine the impact of an artificial intelligence software predicting malignancy in the management of incidentally discovered lung nodules.

Materials and methods

In this retrospective study, all lung nodules ≥ 6 mm and ≤ 30 mm incidentally discovered on emergency CT scans performed between June 1, 2017 and December 31, 2017 were assessed. Artificial intelligence software using deep learning algorithms was applied to determine their likelihood of malignancy: most likely benign (AI score < 50%), undetermined (AI score 50–75%) or probably malignant (AI score > 75%). Predictions were compared to two-year follow-up and Brock's model.

Results

Ninety incidental pulmonary nodules in 83 patients were retrospectively included. 36 nodules were benign, 13 were malignant and 41 remained indeterminate at 2 years follow-up.

AI analysis was possible for 81/90 nodules. The 34 benign nodules had an AI score between 0.02% and 96.73% (mean = 48.05 ± 37.32), while the 11 malignant nodules had an AI score between 82.89% and 100% (mean = 93.9 ± 2.3). The diagnostic performance of the AI software for positive diagnosis of malignant nodules using a 75% malignancy threshold was: sensitivity = 100% [95% CI 72%-100%]; specificity = 55.8% [38–73]; PPV = 42.3% [23–63]; NPV = 100% [82–100]. With its apparent high NPV, the addition of an AI score to the initial CT could have avoided a guidelines-recommended follow-up in 50% of the benign pulmonary nodules (6/12 nodules).

Conclusion

Artificial intelligence software using deep learning algorithms presents a strong NPV (100%, with a 95% CI 82–100), suggesting potential use for reducing the need for follow-up of nodules categorized as benign.

Rationale and objectives

To improve the image quality of CT pulmonary angiography (CTPA) using a patient-specific timing protocol.

Material and methods

A total of 24 swine (48.5 ± 14.3 kg) underwent continuous contrast-enhanced dynamic CT acquisition over 30 s to capture the pulmonary arterial input function (AIF). Multiple contrast injections were made under different cardiac outputs (1.4–5.1 L/min), resulting in a total of 154 AIF curves. The volume scans with maximal enhancement in these AIF curves were retrospectively selected as the reference standard (group A). Two prospective CTPA protocols with bolus-tracking were then simulated using these AIF curves: one used a fixed delay of 5 s between triggering and CTPA acquisition (group B), while the other used a specific delay based on one-half of the contrast injection duration (group C). The mean attenuation, signal-to-noise (SNR) and contrast-to-noise ratios (CNR) between the three groups were then compared using independent sample t-test. Subjective image quality scores were also compared using Wilcoxon-Mann-Whitney test.

Results

The mean attenuation of pulmonary arteries for group A, B and C (expressed in [HU]) were 870.1 ± 242.5 HU, 761.1 ± 246.7 HU and 825.2 ± 236.8 HU, respectively. The differences in the mean SNR and CNR between Group A and Group C were not significant (SNR: 65.2 vs. 62.4, CNR: 59.6 vs. 56.4, both p > 0.05), while Group B was significantly lower than Group A (p < 0.05).

Conclusion

The image quality of CT pulmonary angiography is significantly improved with a timing protocol determined using contrast injection delivery time, as compared with a standard timing protocol with a fixed delay between bolus triggering and image acquisition.

Purpose

To compare tomosynthesis performance to radiography for the differentiation of sacroiliitis versus normal or degenerative changes in sacroiliac joints in patients with suspected axial spondyloarthritis (SpA).

Materials and methods

Radiography, tomosynthesis and CT of sacroiliac joints (29 patients) were performed on the same day in consecutive patients with suspected SpA. The examinations were retrospectively read independently, blinded by two radiologists (one junior and one senior, and twice by one junior). Interobserver and intraobserver agreement was evaluated using the kappa coefficient. Effective doses for each imaging sensitivity, specificity and accuracy were assessed and compared with CT as gold standard.

Results

CT detected 15/58 joints with sacroiliitis. The imaging sensitivity, specificity and accuracy were 60%, 84% and 44%, respectively, for radiography and 87%, 91% and 77% for tomosynthesis. The mean effective dose for tomosynthesis was significantly lower than that of CT (5-fold less) and significantly higher than that of radiography (8-fold more).

Conclusion

Tomosynthesis is superior to radiography for sacroiliitis detection in patients with suspected SpA, with 5-fold less radiation exposure than CT.

Rationale and objectives

To support cardiac MR acquisitions during breathing without ECG, we developed software to mitigate the effects of respiratory displacement of the heart. The algorithm resolves respiratory motions and cardiac cycles from DICOM files. The new software automatically detects heartbeats from expiration and inspiration to decrease apparent respiratory motion.

Materials and methods

Our software uses principal component analysis to resolve respiratory motions from cardiac cycles. It groups heartbeats from expiration and inspiration to decrease apparent respiratory motion. The respiratory motion correction was evaluated on short-axis views (acquired with compressed sensing) of 11 healthy subjects and 8 cardiac patients. Two expert radiologists, blinded to the processing, assessed the dynamic images in terms of blood-myocardial contrast, endocardial interface definition, and motion artifacts.

Results

The smallest correlation coefficients between end-systolic frames of the original dynamic scans averaged 0.79. After segregation of cardiac cycles by respiratory phase, the mean correlation coefficients between cardiac cycles were 0.94±0.03 at end-expiration and 0.90±0.08 at end-inspiration. The improvements in correlation coefficients were significant in paired t-tests for healthy subjects and heart patients at end-expiration. Clinical assessment preferred cardiac cycles during end-expiration, which maintained or enhanced scores in 90% of healthy subjects and 83% of the heart patients. Performance remained high with arrhythmia and irregular breathing present.

Conclusion

Heartbeats collected from end-expiration mitigate respiratory motion and are accessible by applying the new software to DICOM files from real-time CMR. Inspiratory heartbeats are also accessible for examination of arrhythmias or abnormalities at end-inspiration.

Objective

Describe the incidence of contrast-induced acute renal injury (CI-AKI) and the changes in hematocrit in a cohort of patients undergoing elective cerebral digital subtraction angiography (DSA).

Methods

In this prospective study, patients undergoing cerebral DSA were assessed for hematocrit level and CI-AKI risk factors before the procedure and for developing CI-AKI 72 h after exposure to the contrast media.

Results

Among 215 patients (109 men, mean age 36.6 years). The most frequently found CI-AKI risk factor was hypertension. There were no cases of permanent renal impairment after 14 days. Significant changes were observed in hematocrit (45.7 ± 4.9, vs. 44.5 ± 4.6, p = 0.001), estimated creatinine clearance (129.7 ± 48.3, vs. 123.1 ± 40.5, p = 0.002), and serum creatinine (0.72 ± 0.19, vs 0.74 ± 0.18, p = 0.031). The mean change in serum creatinine 72 h after contrast administration was +0.27 ± 0.10 mg/dL (p < 0.05).

Conclusions

The incidence of CI-AKI after elective cerebral DSA was 1.4%. A significant decrease in hematocrit was observed up to 72 h after the procedure.

Background and purpose

Cerebral microbleeds (CMBs) and fluid-attenuated-inversion recovery (FLAIR) hyperintensities on brain MRI scans after radiotherapy (RT) are considered markers for microvascular damage and related cognitive changes. However, the spatial distribution using existing scoring systems as well as colocation of these imaging biomarkers remain unclear, hampering clinical interpretation. This study aims to elucidate the distribution and colocation of these markers in patients with lower grade glioma (LGG).

Materials and methods

CMBs were spatially classified on retrospective 1.5 T susceptibility weighted MRI scans according to the existing Microbleed Anatomical Rating Scale (MARS) and were additionally scored for being located in hippocampus, amygdala, cortex, white matter (WM), grey matter (GM), WM/GM junction and for their spatial relation to FLAIR hyperintensities. Scoring was performed for whole, ipsilateral and contralateral cerebrum (with respect to tumour bulk).

Results

Fifty-one scans were included of which 28 had at least one CMB. The majority of CMBs were localized in the lobar area and in deep and periventricular white matter (DPWM) - generally in WM. Only few CMBs were found in GM. In scans obtained up to 7 years after RT completion the majority of CMBs were not colocalized with FLAIR hyperintensities.

Conclusion

CMBs and FLAIR hyperintensities appear to be separate imaging biomarkers for radiation therapy induced microvascular damage, as they are not colocalized in patients with LGG, especially not early on after completion of RT.

Objective

CT perfusion (CTp) values are affected by CT scan acquisition duration (t_acq); their reproducibility is adversely affected by uncertainty in their measurement. The objectives were to assess the effects of t_acq on CTp parameter values in metastases from renal cell carcinoma (mRCC) in thoracic and abdominal locations.

Materials and Methods

131 CTp evaluations in 53 patients with mRCC were retrospectively analyzed by distributed parameter modeling to yield tissue blood flow (BF), blood volume (BV), mean transit time (MTT), permeability (PS), and also hepatic arterial perfusion (HAP) and hepatic arterial fraction (HAF) for liver metastases and normal liver, with t_acq from 25 to 590 s. Penalized piecewise polynomial regression (SPLINE) characterized functional relationships between CTp parameters and acquisition duration, t_acq. Evidence for time-invariance was evaluated for each parameter at multiple time points by conducting inference on the fitted derivative to assess its proximity to zero as a function of acquisition time. Equivalence testing was implemented with three levels of confidence (low (20%), moderate (70%), high (95%)).

Results

Systematic and non-systematic variability was observed for CTp parameter values with limited t_acq. All parameters in all locations approached increasing stability with increasing t_acq. PS, HAP and HAF required longer acquisition times than BF, BV and MTT to attain comparable levels of stability. Stabilization tended to require longer acquisition in liver than other tissues. t_acq=380 s was required to obtain at least moderate level of confidence for all parameters and organs.

Conclusion

Increasing t_acq yields increasingly more stable CT perfusion parameters, and thereby better reproducibility.