Regional Pulmonary Morphology and Function: Photon-counting CT Assessment.

Background Experience with functional CT in the lungs without additional equipment in clinical routine is limited. Purpose To report initial experience and evaluate the robustness of a modified chest CT protocol and photon-counting CT (PCCT) for comprehensive analysis of pulmonary vasculature, perfusion, ventilation, and morphologic structure in a single examination. Materials and Methods In this retrospective study, consecutive patients with clinically indicated CT for various known and unknown pulmonary function impairment (six subgroups) were included between November 2021 and June 2022. After administration of an intravenous contrast agent, inspiratory PCCT was followed by expiratory PCCT after a delay of 5 minutes. Advanced automated postprocessing was performed, and CT-derived functional parameters were calculated (regional ventilation, perfusion, late contrast enhancement, and CT angiography). Mean intravascular contrast enhancement in the mediastinal vessels and radiation dose were determined. Using analysis of variance, the mean values of lung volumes, attenuation, ventilation, perfusion, and late contrast enhancement were tested for differences between subgroups of patients. Results In 166 patients (mean age, 63.2 years ± 14.2 [SD]; 106 male patients), all CT-derived parameters could be acquired (84.7% success rate; 166 of 196 patients). At the inspiratory examination, mean density was 325 HU in the pulmonary trunk, 260 HU in the left atrium, and 252 HU in the ascending aorta. The mean dose-length product for inspiration and expiration was 110.32 mGy · cm and 109.47 mGy · cm, respectively; the mean CT dose index for inspiration and expiration was 3.22 mGy and 3.09 mGy, respectively (less than the mean total radiation dose of 8-12 mGy, which is diagnostic reference level). Significant differences (P < .05) between the subgroups were found for all assessed parameters. Visual inspection allowed for voxelwise assessment of morphologic structure and function. Conclusion The proposed PCCT protocol allowed for a dose-efficient and robust simultaneous evaluation of pulmonary morphologic structure, ventilation, vasculature, and parenchymal perfusion in a procedure requiring advanced software but no additional hardware. © RSNA, 2023.

Fully Integrated Laser Guidance for CT-Based Punctures: A Study in Phantoms and Patients.

PURPOSE: To test the hypothesis of equal or even superior applicability and accuracy of a fully integrated, laser-based computed tomography (CT) navigation system compared with conventional CT guidance for percutaneous interventions. MATERIALS AND METHODS: CT-guided punctures were first performed in phantoms. Four radiologists with different experience levels (2 residents (L.B., C.D.) and 2 board-certified radiologists (B.M., K.R.) performed 48 punctures using both conventional image-guided and laser-guided approaches. Subsequently, 12 punctures were performed in patients during a clinical pilot trial. Phantom targets required an in-plane or a single-/double-angulated, out-of-plane approach. Planning and intervention time, control scan number, radiation exposure, and accuracy of needle placement (measured by deviation of the needle tip to the designated target) were assessed for each guidance technique and compared (Mann-Whitney U test and t test). Patient interventions were additionally analyzed for applicability in a clinical setting. RESULTS: The application of laser guidance software in the phantom study and in 12 human patients in a clinical setting was both technically and clinically feasible in all cases. The mean planning time (P = .009), intervention time (P = .005), control scan number (P < .001), and radiation exposure (P = .013) significantly decreased for laser-navigated punctures compared with those for conventional CT guidance and especially in punctures with out-of-plane-trajectories. The accuracy significantly increased for laser-guided interventions compared with that for conventional CT (P < .001). CONCLUSIONS: Interventional radiologists with differing levels of experience performed faster and more accurate punctures for out-of-plane trajectories in the phantom models, using a new, fully integrated, laser-guided CT software and demonstrated excellent clinical and technical success in initial clinical experiments.

Intraarterial embolizations in life-threatening spontaneous retroperitoneal and rectus sheath hemorrhage (SRRSH): a three-center experience.

PURPOSE: To retrospectively evaluate the technical and clinical success of interventional treatments employed in three University medical centers and to develop work-flow recommendations for intra-arterial embolizations in patients with life-threatening spontaneous retroperitoneal and rectus sheath hemorrhage (SRRSH). MATERIALS AND METHODS: Retrospective evaluation of all patients with contrast-enhanced CT and digital subtraction angiography (DSA) for SRRSH from 01/2018 to 12/2022, amounted to 91 interventions in 83 patients (45f, 38m) with a mean age of 68.1 ± 13.2 years. Analysis of the amount of bleeding and embolized vessels, choice of embolization material, technical success, and 30-day mortality was performed. RESULTS: Pre-interventional contrast-enhanced CT demonstrated active contrast extravasation in 79 cases (87%). DSA identified a mean of 1.4 ± 0.88 active bleeds in all but two interventions (98%), consisting of 60 cases with a singular and 39 cases of >1 bleeding artery, which were consecutively embolized. The majority of patients underwent embolization with either n-butyl-2-cyanoacrylate (NBCA; n=38), coils (n=21), or a combination of embolic agents (n=23). While the technical success rate was documented at 97.8%, 25 patients (30%) died within 30 days after the initial procedure, with mortality rates ranging from 25 to 86% between the centers, each following different diagnostic algorithms. CONCLUSION: Embolotherapy is a safe therapy option with high technical success rates in patients with life-threatening SRRSH. To maximize clinical success and survival rates, we propose a standardized approach to angiography as well as a low threshold for re-angiography.

The impact of the field of view (FOV) on image quality in MDCT angiography of the lower extremities.

OBJECTIVES: To evaluate the impact of the reconstructed field-of-view (FOV) on image quality in computed-tomography angiography (CTA) of the lower extremities. METHODS: A total of 100 CTA examinations of the lower extremities were acquired on a 2 × 192-slice multidetector CT (MDCT) scanner. Three different datasets were reconstructed covering both legs (standard FOV size) as well as each leg separately (reduced FOV size). The subjective image quality was evaluated for the different vessel segments (femoral, popliteal, crural, pedal) by three readers using a semi-quantitative Likert scale. Additionally, objective image quality was assessed using an automated image quality metric on a per-slice basis. RESULTS: The subjective assessment of the image quality showed an almost perfect interrater agreement. The image quality of the small FOV datasets was rated significantly higher as compared to the large datasets for all patients and vessel segments (p < 0.05) with a tendency towards a higher effect in smaller vessels. The difference of the mean scores between the group with the large FOV and small FOV was 0.68 for the femoral level, 0.83 for the popliteal level, 1.12 for the crural level, and 1.08 for the pedal level. The objective image quality metric also demonstrated a significant improvement of image quality in the small FOV datasets. CONCLUSIONS: Side-separated reconstruction of each leg in CTA of the lower extremities using a small reconstruction FOV significantly improves image quality as compared to a standard reconstruction with a large FOV covering both legs. KEY POINTS: • In CT angiography of the lower legs, the side-separated reconstruction of each leg using a small field-of-views improves image quality as compared to a standard reconstruction covering both legs. • The side-separated reconstruction can be readily implemented at every commercially available CT scanner. • There is no need for additional hardware or software and no additional burden to the patient.

Impact of sarcopenia in advanced and metastatic soft tissue sarcoma.

INTRODUCTION: Advanced or metastatic soft tissue sarcoma (a/mSTS) is associated with a dismal prognosis. Patient counseling on treatment aggressiveness is pivotal to avoid over- or undertreatment. Recently, evaluation of body composition markers like the skeletal muscle index (SMI) became focus of interest in a variety of cancers. This study focuses on the prognostic impact of SMI in a/mSTS, retrospectively. METHODS: 181 a/mSTS patients were identified, 89 were eligible due to prespecified criteria for SMI assessment. Baseline CT-Scans were analyzed using an institutional software solution. Sarcopenia defining cut-off values for the SMI were established by optimal fitting method. Primary end point was overall survival (OS) and secondary endpoints were progression free survival (PFS), disease control rate (DCR), overall response rate (ORR). Descriptive statistics as well as Kaplan Meier- and Cox regression analyses were administered. RESULTS: 28/89 a/mSTS patients showed sarcopenia. Sarcopenic patients were significantly older, generally tended to receive less multimodal therapies (62 vs. 57 years, P = 0.025; respectively median 2.5 vs. 4, P = 0.132) and showed a significantly lower median OS (4 months [95%CI 1.9-6.0] vs. 16 months [95%CI 8.8-23.2], Log-rank P = 0.002). Sarcopenia was identified as independent prognostic parameter of impaired OS (HR 2.40 [95%-CI 1.4-4.0], P < 0.001). Moreover, DCR of first palliative medical treatment was superior in non-sarcopenic patients (49.2% vs. 25%, P = 0.032). CONCLUSION: This study identifies sarcopenia as a prognostic parameter in a/mSTS. Further on, the data suggest that sarcopenia shows a trend of being associated with first line therapy response. SMI is a promising prognostic parameter, which needs further validation.

CO2-based C-arm computed tomography (CACT) of the pelvic arteries: feasibility and diagnostic performance in comparison to CO2-angiography in patients with peripheral arterial disease.

BACKGROUND: Patients with substantially impaired kidney function and peripheral arterial disease (PAD) underwent comparative CO2-based depiction of the pelvic arteries (PAs). PURPOSE: To evaluate the feasibility and diagnostic performance of CO2-based C-arm computed tomography (CACT) and compare its depiction of PAs with CO2-digital subtraction angiography (DSA). MATERIAL AND METHODS: Fifteen patients (10 men, mean age 70 ± 11 years) with PAD received CO2-DSA and CO2-CACT of the PAs, depicted from the aorta to femoral arteries. These were divided into nine segments (135 in total) and graded by two independent readers for image quality (IQ; 1 = sufficient, 2 = minimal impairments, 3 = insufficient, 4 = outside field of view) and subsequent stenosis grading (SG; grade 1: normal to grade 4: occlusion), under exclusion of all segments with insufficient IQ. Inter-observer and inter-modality agreement calculation and subsequent consensus reading were performed and correlated to a standard of reference (StOR), representing a modality consensus. RESULTS: Of 135 segments, 117 showed sufficient IQ, excluding 18 segments (10 CACT, 8 DSA). Inter-observer agreement for IQ and consecutive SG demonstrated good to excellent agreement: IQDSA: κ = 0.83, IQCACT: κ = 0.76; StenosisDSA: κ = 0.71, StenosisCACT: κ = 0.84. Inter-modality agreement for SG lay at κ = 0.76 and κ = 0.65, respectively. More stenoses could be detected by CACT, and analysis of pooled consensus values of SG in CACTcons versus StOR showed an excellent agreement (κ = 0.96) that proved considerably higher than the moderate agreement between consensus values in DSAcons versus StOR (κ = 0.43). CONCLUSION: CO2-CACT proved feasible, and has the potential to optimize angiographic work-up of PAD in patients with contraindications for other contrast media.

Arterial attenuation in individualized computed tomography pulmonary angiography injection protocol adjusted based on the patient's body mass index.

BACKGROUND: The aim of this study was to optimize computed tomography pulmonary angiography (CTPA) protocols with regard to improve vascular attenuation without increasing contrast media (CM) volumes. Therefore, we compared the standard CTPA protocol to an individualized contrast media injection protocols adjusted for the patient's body mass index (BMI). MATERIALS AND METHODS: Two groups of 295 patients with suspected pulmonary embolism (PE) have been receiving CTPA. Group 1 received a standard protocol without taking patient's BMI into account. Group 2 received a CTPA scan, where dose and flow rate of CM injections were adjusted for the patient's BMI. Images were retrospectively analyzed by drawing regions of interests in defined positions in the superior vena cava, descending aorta, the pulmonary main trunk as well as the left and right lower lobe arteries. Intravascular attenuation, contrast volumes, and flow rates were compared using unpaired t-tests. Furthermore, a qualitative image analysis was performed by two experienced readers blinded for the protocol used for image acquisition to evaluate the image quality and arterial attenuation. RESULTS: Patient's BMI was similar in both the groups (27.5 ± 1.5 kg/m2 vs. 28.4 ± 2.1 kg/m2; P = 0.67). Contrast volumes were lower (54.2 ± 4.8 ml vs. 55 ml; P < 0.05), and flow rates (4.1 ± 0.3 ml/s vs. 3.5 ml/s; P < 0.05) were significantly higher in the individualized protocol. The qualitative image analysis yielded an agreement on diagnostic interpretability in the individualized and standard group of 49% and 51% (95% Wilson confidence interval for mean), respectively. CONCLUSION: An individualized CTPA protocol based on the patient's BMI reduced the contrast media volume and led to an increased pulmonary artery enhancement improving image quality, particularly in the evaluation of the peripheral pulmonary arteries. Thus, contrast media volumes in CTPA should be adjusted for the patient's BMI.

C-Arm computed tomography (CACT)-guided balloon pulmonary angioplasty (BPA): Evaluation of patient safety and peri- and post-procedural complications.

AIM: To assess the frequency and severity of complications of balloon pulmonary angioplasty (BPA) using C-arm computed tomography (CACT) guidance. MATERIAL AND METHODS: 266 consecutive interventions in 67 patients (42 females, mean age 66 ± 13 years) were included. Selective CACT was acquired prior to the intervention for three-dimensional (3D) guidance and to select appropriate balloon size based on the measured vessel diameter. Complications during and after the procedure, the need for further interventions and the impact on patient safety and outcome were assessed and categorised according to the SIR Classification System to Complications by Outcome (Grade A-F). RESULTS: Overall, 237 interventions were conducted without any complications (89.1%). Minor complications not requiring additional treatment occurred during or after 25 procedures (9.4%), including recurring dry cough in four patients during a total of 11 interventions (4.1%) (Grade A), three focal dissections of the targeted pulmonary artery (1.1%), four cases of pulmonary haemorrhage (1.5%), one case of reperfusion oedema (0.4%) and six cases of post-interventional short-term hemoptysis (2.3%) (Grade B). Four cases of major complications requiring additional treatment were observed (1.5%): one case of pulmonary haemorrhage (0.4%) and two cases of post-interventional haemoptysis (0.8%), all resolved after medical therapy without requiring further intervention, and one case of atrial tachycardia induced during catheterisation, subsequently requiring pharmacological cardioversion (0.4%) (Grade C). No fatal or life-threatening peri- or post-interventional complications or mortality were observed (Grade D-F). CONCLUSION: BPA performed under CACT guidance appears to be a safe procedure with a low risk of severe complications. KEY POINTS: • CACT guidance of BPA is safe and successful. • CACT-guided BPA procedures have a low complication profile. • CACT guidance is a valuable tool to navigate BPA.

Percutaneous hepatic perfusion (chemosaturation) with melphalan in patients with intrahepatic cholangiocarcinoma: European multicentre study on safety, short-term effects and survival.

OBJECTIVES: Cholangiocarcinoma is the second most common primary liver tumour with a poor overall prognosis. Percutaneous hepatic perfusion (PHP) is a directed therapy for primary and secondary liver malignancies, and its efficacy and safety have been shown in different entities. The purpose of this study was to prove the safety and efficacy of PHP in patients with unresectable intrahepatic cholangiocarcinoma (iCCA). PATIENTS AND METHODS: We retrospectively reviewed data from 15 patients with unresectable iCCA treated with PHP in nine different hospitals throughout Europe. Overall response rates (ORR) were assessed according to response evaluation criteria in solid tumours (RECIST1.1). Overall survival (OS), progression-free survival (PFS) and hepatic PFS (hPFS) were analysed using the Kaplan-Meier estimation. Adverse events (AEs) and toxicity were evaluated. RESULTS: Fifteen patients were treated with 26 PHPs. ORR was 20%, disease control was achieved in 53% after the first PHP. Median OS was 26.9 months from initial diagnosis and 7.6 months from first PHP. Median PFS and hPFS were 122 and 131 days, respectively. Patients with liver-only disease had a significantly longer median OS compared to patients with locoregional lymph node metastases (12.9 vs. 4.8 months, respectively; p < 0.01). Haematological toxicity was common, but manageable. No AEs of grade 3 or 4 occurred during the procedures. DISCUSSION: PHP is a standardised and safe procedure that provides promising response rates and survival data in patients with iCCA, especially in non-metastatic disease. KEY POINTS: • Percutaneous hepatic perfusion (PHP) offers an additional locoregional therapy strategy for the treatment of unresectable primary or secondary intrahepatic malignancies. • PHP is a standardised and safe procedure that provides promising response rates and survival data in patients with intrahepatic cholangiocarcinoma (iCCA), especially in non-metastatic disease. • Side effects seem to be tolerable and comparable to other systemic or local treatment strategies.

MR-guided percutaneous sclerotherapy of low-flow vascular malformations: Clinical experience using a 1.5 tesla MR system.

PURPOSE: To demonstrate the feasibility, safety, and effectiveness of image-guided sclerotherapy of low-flow vascular malformations using a 1.5 Tesla (T) MR scanner with real-time imaging capability and in-suite fluoroscopy. MATERIALS AND METHODS: Thirty-three procedures were performed with real-time 1.5T MR-guidance on 22 patients with a vascular malformation in the neck (n = 2), chest (n = 6), abdomen and pelvis (n = 15), and extremities (n = 11). Quantitative analysis was performed for changes in (a) planning time, (b) targeting time (interval between needle skin puncture and lesion access), (c) intervention time (interval between needle skin puncture and needle removal), and (d) total procedure time. Qualitative analysis was performed for (a) success of therapy and (b) occurrence of complications. RESULTS: Technical success was achieved in 29 of 33 procedures. The average planning time did not significantly change between the first seven procedures and the last seven procedures (P = 0.447). The average targeting time decreased by 0:24:45 (hours:minutes:seconds) (P = 0.043), the average intervention time decreased by 0:26:58 (P = 0.022), and the average procedure time decreased by 0:28:41 (P = 0.046) when comparing the first seven procedures and the last seven procedures. Overall, there was an improvement in the patients' predominant symptoms following 82% of procedures, including a significant decrease in average pain following therapy (P < 0.001). There was a minor complication rate of 3% with no major complications. CONCLUSION: MR-guided percutaneous sclerotherapy seems to be a safe, effective, and versatile technique for treating low-flow vascular malformations. LEVEL OF EVIDENCE: 3 J. Magn. Reson. Imaging 2017;45:1154-1162.

Chronic thromboembolic pulmonary hypertension: Evaluation of 2D-perfusion angiography in patients who undergo balloon pulmonary angioplasty.

OBJECTIVE: To evaluate the feasibility of 2D-perfusion angiography (2D-PA) in order to quantify perfusion changes of the lung parenchyma pre- and post-balloon pulmonary angioplasty (BPA). METHODS: Thirty consecutive interventions in 16 patients with 99 treated pulmonary artery segments were included. To quantify changes in pulmonary blood flow using 2D-PA, the acquired digital subtraction angiographies (DSA) pre- and post-BPA were post-processed. A reference ROI in the treated pulmonary artery and a distal target ROI in the lung parenchyma were placed in corresponding areas on DSA pre- and post-BPA. Time to peak (TTP), peak density (PD) and area under the curve (AUC) were assessed. The ratios reference ROI to target ROI (TTPparenchyma/TTPinflow; PDparenchyma/PDinflow; AUCparenchyma/AUCinflow) were calculated. Relative differences of the 2D-PA parameters were correlated to changes in the pulmonary-flow-grade-score. RESULTS: The pulmonary-flow-grade-score improved after BPA (p<0.0001). Likewise, the ratio TTPparenchyma/TTPinflow shortened by 10% (p=0.0002), the PDparenchyma/PDinflow increased by 46% (p<0.0001) and the AUCparenchyma/AUCinflow increased by 36% (p<0.0001). A significant correlation between changes in the pulmonary-flow-grade-score and changes in PDparenchyma/PDinflow (ρ=0.48, p<0.0001) and AUCparenchyma/AUCinflow (ρ=0.31, p=0.0018) was observed. CONCLUSION: Quantification of pulmonary perfusion pre- and post-BPA using 2D-PA is feasible and has the potential to improve monitoring of BPA. KEY POINTS: • Quantification of BPA results by use of 2D-PA is feasible. • 2D-PA allows objective assessment of changes in lung parenchymal perfusion. • 2D-PA has the potential to optimize BPA.

Balloon pulmonary angioplasty: applicability of C-Arm CT for procedure guidance.

PURPOSE: To investigate the feasibility of and compare two C-Arm CT (CACT) guidance methods during balloon pulmonary angioplasty (BPA). MATERIAL AND METHODS: Forty-two BPAs [27 CTEPH patients (nine males, 70 ± 14y)] targeting 143 pulmonary arteries were included. Twenty-two BPAs were guided by contrast-enhanced CACT acquired immediately before BPA (G3D). In another 20 BPAs (G2D), two orthogonal fluoroscopy images of the chest where acquired to compute a registration of a previously acquired CACT. Volume rendering-based graphic representations (VRT guidance) were generated indicating the origin and course of the vessels. Based on VRT guidance, the intervention was planned. Procedure durations and radiation exposure data were compared between the two groups (Wilcoxon test). RESULTS: The overall intervention time was approximately 2 h in both groups (p = 0.31). BPA was successfully performed in G3D 91 % and G2D 94 %. No significant difference was found concerning the mean dose area product (DAP) related to fluoroscopy (p = 0.38), while DAP related to DSA was slightly higher in G3D (p = 0.048). Overall, DAP was significantly higher in G3D (p = 0.002). CONCLUSIONS: The use of CACT for procedure guidance in patients undergoing BPA is feasible and accurate. Image fusion of a pre-acquired CACT can be used to decrease radiation exposure due to multiple BPA sessions. KEY POINTS: • BPA guidance by CACT overlay is feasible and safe. • 2D3D image fusion for BPA guidance is accurate. • Image fusion can reduce patient radiation dose due to repeated BPA sessions.

Parametric response mapping of contrast-enhanced biphasic CT for evaluating tumour viability of hepatocellular carcinoma after TACE.

OBJECTIVES: To determine the feasibility and role of parametric response mapping (PRM) for quantitative assessment of regional contrast-enhancement patterns in hepatocellular carcinoma (HCC). METHODS: Biphasic CT of 19 patients receiving repetitive conventional transarterial chemoembolisation (cTACE) for intermediate stage HCC were retrospectively analysed at baseline and follow-up at 3, 6, and 9 months. Voxel-based registration of arterial and porto-venous phases, with segmentation of the largest target lesion was performed. Frequency distribution plots of density-pairs of segmented voxels were generated. To differentiate necrotic, hypervascular and non-hypervascular tumour, and lipiodol/calcification, thresholds of 30, 100, and 300 HU were applied. Changes in density frequency plots over time were analysed and compared to response and assessment criteria (WHO, RECIST, EASL, mRECIST) and survival. RESULTS: PRM was feasible in all cases. Tumour volumes and hypervascular/non-hypervascular volume ratio showed significant longitudinal decrease (p < 0.05). Hypervascular volume at baseline was inversely correlated to survival (R = -0.57, p = 0.005). The only predictive parameter following cTACE to show significant survival difference was the change of the viable/non-viable ratio (p = 0.044), whereas common response assessment criteria showed no significant difference in survival. CONCLUSIONS: PRM allows a quantitative and more precise assessment of regional tumour vascularisation patterns and may be helpful for TACE treatment planning and response assessment. KEY POINTS: • PRM allows more precise assessment of tumour vascularisation compared to conventional evaluation • PRM is beneficial for cTACE treatment planning and response assessment • PRM allows a quantitative assessment of regional contrast enhancement patterns.

Pulmonary Artery Imaging in Patients with Chronic Thromboembolic Pulmonary Hypertension: Comparison of Cone-Beam CT and 64-Row Multidetector CT.

PURPOSE: To compare the depiction of pulmonary arteries in pulmonary arterial catheter-based contrast-enhanced cone-beam CT with peripheral intravenous contrast-enhanced multidetector CT in patients with suspected chronic thromboembolic pulmonary hypertension. MATERIAL AND METHODS: In 20 patients (15 men and 5 women, 63.4 y ± 16.3), cone-beam CT using a catheter placed in the main pulmonary artery and 64-row multidetector CT using an appropriate venous access were performed. Contrast enhancement was measured in the main pulmonary artery, the right and left pulmonary arteries, and the left atrium. The amount of peripheral vessel conspicuity adjacent to the pleural surface (distance from vessel-to pleura) was measured. Two readers (R1, R2) independently evaluated the pulmonary arteries for image quality and pathologic findings in both modalities. RESULTS: Contrast density was higher in the main pulmonary artery and right and left pulmonary arteries (P < .002) and lower in the left atrium (P = .001) on cone-beam CT. The smallest distance between clearly delineated vessels and the pleura was significantly lower on cone-beam CT images (P < .0001). Interobserver agreement was good for cone-beam CT (κ = 0.79) and multidetector CT (κ = 0.78), whereas intermodality agreement was moderate (R1, κ = 0.60; R2, κ = 0.59). Both readers detected more weblike stenoses with cone-beam CT (76; 22%) compared with multidetector CT (25; 7%). CONCLUSIONS: Cone-beam CT shows improved contrast between pulmonary arteries and the left atrium and allows a more detailed depiction of the pulmonary arteries.

Chronic Lung Allograft Dysfunction: Oxygen-enhanced T1-Mapping MR Imaging of the Lung.

PURPOSE: To evaluate oxygen-enhanced T1-mapping magnetic resonance (MR) imaging of the lungs for detection of chronic lung allograft dysfunction (CLAD) in patients who have undergone double lung transplantation. MATERIALS AND METHODS: The local ethics committee approved this study. Seventy-six recipients of double lung allografts who underwent MR imaging of the lungs during an outpatient visit between 2011 and 2013 were included in this study after they provided written informed consent. Patients were classified as having CLAD on the basis of spirometric results and were divided into three groups: no CLAD (bronchiolitis obliterans syndrome level 0 [BOS 0]), early CLAD (BOS 0p), and late-stage CLAD (BOS 1-3). Coronal T1 maps of the lungs were acquired with the patient breathing room air and 100% oxygen by using an inversion-recovery snapshot fast low-angle shot sequence at 1.5 T. The median and interquartile range of T1 values at room air and at 100% oxygen and the oxygen transfer function were calculated. Statistical analysis was performed with analysis of variance and the Tukey honestly significant difference test or the Kruskal-Wallis test and the Mann-Whitney U test (α = 0.05). Bonferroni correction was applied for multiple comparisons. RESULTS: The oxygen transfer function was significantly lower in patients in the BOS 0p (P = .025) and BOS 1-3 groups (P = .003) than it was in the patients with BOS 0. Absolute T1 values (room air, P = .66; 100% oxygen, P = .67) did not differ significantly among the groups. The heterogeneity of T1 values, measured by using the interquartile range, showed a strong trend toward higher values in patients with BOS (room air, P = .06; 100% oxygen, P = .08). CONCLUSION: Oxygen transfer function may serve as an early marker for detection of CLAD.

Quantification of pulmonary inflammation after segmental allergen challenge using turbo-inversion recovery-magnitude magnetic resonance imaging.

RATIONALE: There is a need to develop novel noninvasive imaging biomarkers that help to evaluate antiinflammatory asthma treatments. OBJECTIVES: To investigate whether the extent of the segmental lung edema measured noninvasively using turbo-inversion recovery-magnitude magnetic resonance imaging (TIRM MRI) corresponds to the severity of the regional allergic reaction determined by the percentage of eosinophils in bronchoalveolar lavage fluid (BAL) 24 hours after segmental allergen challenge in patients with asthma compared with normal control subjects. METHODS: Eleven volunteers with allergic asthma and five healthy volunteers underwent segmental challenges with different allergen doses by two bronchoscopies 24 hours apart. They had lung MRI at baseline and 6 and 24 hours after segmental challenge. MRI TIRM scores were correlated with the eosinophilic response at 24 hours. MEASUREMENTS AND MAIN RESULTS: In patients with asthma, there were significant differences of eosinophil percentages in BAL at 24 hours from segments given standard-dose, low-dose, or no allergen (saline) (P < 0.001). Correspondingly significant differences between the TIRM score in allergen standard-dose, low-dose, and saline-treated segments were observed at 24 hours post-challenge (P < 0.001). With increasing TIRM score at 24 hours the percent eosinophils per segment 24 hours post-challenge also increased accordingly (P < 0.001). There was interobserver agreement for TIRM score grading (kappa = 0.72 for 24-h time point). CONCLUSIONS: The MRI-based noninvasive TIRM score is a promising biomarker for the noninvasive detection of the inflammatory response after segmental allergen challenge in patients with asthma and may serve to monitor the therapeutic effectiveness of novel antiinflammatory drugs in future human trials.

[Spontaneous retroperitoneal and rectus sheath hematomas and their interventional therapy: a review]. / Spontane retroperitoneale und Rektusscheidenhämatome und ihre interventionelle Therapie: ein Review.

BACKGROUND: Retroperitoneal and rectus sheath hemorrhage (RRSH) has been described as a potentially fatal condition with mortality rates of up to 30 % due to the risk of exsanguination in combination with often nonspecific clinical symptoms. Patients at risk are > 65 years of age as well as those receiving anticoagulation/antiplatelet medicine. Classifications based on etiology consist of trauma, surgery, and/or underlying vascular pathologies, though spontaneous occurrences without precipitating factors have been reported and are expected to increase with the high number of patients undergoing anticoagulant therapy. METHOD: Analysis, summary, and discussion of published review articles and expert recommendations. RESULTS: The most commonly described symptom during clinical examination is abdominal pain. However, depending on the volume loss, clinical symptoms may include signs of abdominal compartment and hemorrhagic shock. Computed tomography angiography (CTA) with high sensitivity and specificity for the presence of active bleeding plays an important role in the detection of RH and RSH. Therapy management is based on different pillars, which include surgical and interventional measures in addition to conservative measures (volume replacement, optimization of coagulation parameters). Due to its lower invasiveness with simultaneously high technical and clinical success rates, interventional therapy in particular has gained increasing importance. CONCLUSION: Diagnostic and therapeutic workup of the patients by an interdisciplinary team is essential for optimal patient care. In case of transcatheter arterial embolization, a standardized approach to the detection of bleeding sites within the vascular territory of the core hematoma appears to favorably influence success and patient outcome. KEY POINTS: · The clinical presentation of retroperitoneal and rectus sheath hematomas can be very heterogeneous and nonspecific. Quick diagnosis is essential due to the relatively high mortality rate (approx. 12-30 %).. · The main risk factors are age > 65 years and the intake of anticoagulants, the use of which has increased 2.5 times in the last 10 years. Coagulopathies, retroperitoneal masses, and hemodialysis are less common causes.. · Computed tomography angiography (CTA) has a high sensitivity and specificity for the presence of active bleeding and has replaced diagnostic subtraction angiography (DSA).. · Treatment should be performed in a multidisciplinary setting with the inclusion of internal medicine, radiology, and surgery. The main indications for embolization are the detection of active contrast extravasation on CTA and the presence of abdominal pain. In cases without active bleeding and with stable vital parameters, conservative treatment measures can be sufficient. Surgical treatment is often reserved for treatment-refractory bleeding with symptoms of abdominal compartment.. · A systematic standardized approach to the detection of bleeding on DSA seems to have advantages regarding technical and clinical success rates.. CITATION FORMAT: · Becker LS, Dewald CLA et al. Spontaneous retroperitoneal and rectus sheath hematomas and their interventional therapy: a review. Fortschr Röntgenstr 2024; 196: 163 - 175.

Image Quality and Radiation Exposure in Abdominal Angiography: A Head-to-Head Comparison of Conventional Detector-Dose-Driven Versus Contrast-to-Noise Ratio-Driven Exposure Control at Various Source-to-Image Receptor Distances and Collimations in a Pilot Phantom and Animal Study.

OBJECTIVES: This phantom and animal pilot study aimed to compare image quality and radiation exposure between detector-dose-driven exposure control (DEC) and contrast-to-noise ratio (CNR)-driven exposure control (CEC) as functions of source-to-image receptor distance (SID) and collimation. MATERIALS AND METHODS: First, an iron foil simulated a guide wire in a stack of polymethyl methacrylate and aluminum plates representing patient thicknesses of 15, 25, and 35 cm. Fluoroscopic images were acquired using 5 SIDs ranging from 100 to 130 cm and 2 collimations (full field of view, collimated field of view: 6 × 6 cm). The iron foil CNRs were calculated, and radiation doses in terms of air kerma rate were obtained and assessed using a multivariate regression. Second, 5 angiographic scenarios were created in 2 anesthetized pigs. Fluoroscopic images were acquired at 2 SIDs (110 and 130 cm) and both collimations. Two blinded experienced readers compared image quality to the reference image using full field of view at an SID of 110 cm. Air kerma rate was obtained and compared using t tests. RESULTS: Using DEC, both CNR and air kerma rate increased significantly at longer SID and collimation below the air kerma rate limit. When using CEC, CNR was significantly less dependent of SID, collimation, and patient thickness. Air kerma rate decreased at longer SID and tighter collimation. After reaching the air kerma rate limit, CEC behaved similarly to DEC. In the animal study using DEC, image quality and air kerma rate increased with longer SID and collimation (P < 0.005). Using CEC, image quality was not significantly different than using longer SID or tighter collimation. Air kerma rate was not significantly different at longer SID but lower using collimation (P = 0.012). CONCLUSIONS: CEC maintains the image quality with varying SID and collimation stricter than DEC, does not increase the air kerma rate at longer SID and reduces it with tighter collimation. After reaching the air kerma rate limit, CEC and DEC perform similarly.

Percutaneous punctures with MR imaging guidance: comparison between MR imaging-enhanced fluoroscopic guidance and real-time MR Imaging guidance.

PURPOSE: To evaluate and compare the technical accuracy and feasibility of magnetic resonance (MR) imaging-enhanced fluoroscopic guidance and real-time MR imaging guidance for percutaneous puncture procedures in phantoms and animals. MATERIALS AND METHODS: The experimental protocol was approved by the institutional animal care and use committee. Punctures were performed in phantoms, aiming for markers (20 each for MR imaging-enhanced fluoroscopic guidance and real-time MR imaging guidance), and pigs, aiming for anatomic landmarks (10 for MR imaging-enhanced fluoroscopic guidance and five for MR imaging guidance). To guide the punctures, T1-weighted three-dimensional (3D) MR images of the phantom or pig were acquired. Additional axial and coronal T2-weighted images were used to visualize the anatomy in the animals. For MR imaging-enhanced fluoroscopic guidance, phantoms and pigs were transferred to the fluoroscopic system after initial MR imaging and C-arm computed tomography (CT) was performed. C-arm CT and MR imaging data sets were coregistered. Prototype navigation software was used to plan a puncture path with use of MR images and to superimpose it on fluoroscopic images. For real-time MR imaging, an interventional MR imaging prototype for interactive real-time section position navigation was used. Punctures were performed within the magnet bore. After completion, 3D MR imaging was performed to evaluate the accuracy of insertions. Puncture durations were compared by using the log-rank test. The Mann-Whitney U test was applied to compare the spatial errors. RESULTS: In phantoms, the mean total error was 8.6 mm ± 2.8 with MR imaging-enhanced fluoroscopic guidance and 4.0 mm ± 1.2 with real-time MR imaging guidance (P < .001). The mean puncture time was 2 minutes 10 seconds ± 44 seconds with MR imaging-enhanced fluoroscopic guidance and 37 seconds ± 14 with real-time MR imaging guidance (P < .001). In the animal study, a tolerable distance (<1 cm) between target and needle tip was observed for both MR imaging-enhanced fluoroscopic guidance and real-time MR imaging guidance. The mean total error was 7.7 mm ± 2.4 with MR imaging-enhanced fluoroscopic guidance and 7.9 mm ± 4.9 with real-time MR imaging guidance (P = .77). The mean puncture time was 5 minutes 43 seconds ± 2 minutes 7 seconds with MR imaging-enhanced fluoroscopic guidance and 5 minutes 14 seconds ± 2 minutes 25 seconds with real-time MR imaging guidance (P = .68). CONCLUSION: Both MR imaging-enhanced fluoroscopic guidance and real-time MR imaging guidance demonstrated reasonable and similar accuracy in guiding needle placement to selected targets in phantoms and animals.

Classification of Diverticular Disease (CDD) - assessment of the intra- and interobserver agreement in abdominal CT scans.

PURPOSE: Along with ultrasound, computed tomography (CT) is one of the imaging modalities of choice in patients with suspected diverticular disease (DD). Recently, a newer Classification of Diverticular Disease (CDD) has been proposed. However, its reliability in daily radiological practice has never been proven. Therefore, our aim was to evaluate the intra- and interobserver agreement of the CDD in abdominal CT scans. METHODS: In this retrospective study, 481 CT scans of patients with suspected DD were included. Two readers (one board-certified radiologist with 6 years of experience, one 3 rd year radiology resident) individually evaluated all CTs in two reading sessions using the CDD. A composite endpoint of a prior consensus reading, follow-up, and intraoperative findings served as the reference. Intra- and interobserver agreement were calculated using Cohen-k statistic. RESULTS: DD was present in 317 cases (66 %), mostly classified as CDD stage 0, 1b, and 2a (28 %, 30 %, und 14 %). Intraobserver agreement was almost perfect for both readers (kappa 0.93 and 0.88). Interobserver agreement was high and improved from substantial (kappa 0.77) in the first reading session to almost perfect (kappa 0.84) in the second reading session. The interobserver agreement was best for CDD types 0 (diverticulosis) and 2c (free perforated diverticulitis) (mean kappa 0.83 and 0.86) and poorest for CDD types 1a (diverticulitis without phlegmon) and 2b (covered diverticulitis with macroabscess) (mean kappa 0.17 and 0.38). Intra- and interobserver agreement of acute uncomplicated (CDD type 1) and acute complicated diverticulitis (CDD type 2) were substantial to almost perfect (mean kappa 0.63-0.86). Agreement with the reference was almost perfect for both observers (mean kappa 0.86 and 0.82). Administration of rectal contrast did not significantly improve the diagnosis. CONCLUSION: The CDD is a classification based on relatively clear imaging characteristics, which can be readily applied by radiologists with different expertise. In our study, the CDD had a high intra- and interobserver agreement, enabling a reliable therapy-related categorization of DD. KEY POINTS: · The Classification of Diverticular Disease (CDD) is an easy-to-use classification for diverticular disease based on relatively clear image features.. · The CDD can be applied equally by radiologists with different levels of experience in the clinical routine.. · The high intra- and interobserver agreement indicates high reliability in the therapy-relevant classification of diverticulitis on CT..