Clinical utility of postprocessed low-dose radiographs in skeletal imaging

Objectives: Radiography remains the mainstay of diagnostic and follow-up imaging. In view of the risks and the increasing use of ionizing radiation, dose reduction is a key issue for research and development. The introduction of digital radiography and the associated access to image postprocessing have opened up new opportunities to minimize the radiation dosage. These advances are contingent upon quality controls to ensure adequate image detail and maintenance of diagnostic confidence. The purpose of this study was to investigate the clinical applicability of postprocessed low-dose images in skeletal radiography. Methods: In our study setting, the median radiation dose for full dose X-rays was 9.61 dGy*cm2 for pelvis, 1.20 dGy*cm2 for shoulder and 18.64 dGy*cm2 for lumbar spine exams. Based on these values, we obtained 200 radiographs for each anatomic region in four consecutive steps, gradually reducing the dose to 84%, 71%, 60% and 50% of the baseline using an automatic exposure control (AEC). 549 patients were enrolled for a total of 600 images. All X-rays were postprocessed with a spatial noise reduction algorithm. Two radiologists assessed the diagnostic value of the radiographs by rating the visualization of anatomical landmarks and image elements on a five-point Likert scale. A mean-sum score was calculated by averaging the two reader's total scores. Given the non-parametric distribution, we used the Mann-Whitney U test to evaluate the scores. Results: Median dosage at full dose accounted for 38.4%, 48 and 53.2% of the German reference dose area product for shoulder, pelvis and lumbar spine, respectively. The applied radiation was incrementally reduced to 21.5%, 18.4% and 18.7% of the respective reference value for shoulder, pelvis and lumbar spine. Throughout the study, we observed an estimable tendency of superior quality at higher dosage in overall image quality. Statistically significant differences in image quality were restricted to the 50% dose groups in shoulder and lumbar spine images. Regardless of the applied dosage, 598 out of 600 images were of sufficient diagnostic value. Conclusion: In digital radiography image postprocessing allows for extensive reduction of radiation dosage. Despite a trend of superior image detail at higher dose levels, overall quality and, more importantly, diagnostic utility of low-dose images was not significantly affected. Therefore, our results not only confirm the clinical utility of postprocessed low-dose radiographs, but also suggest a widespread deployment of this advanced technology to ensure further dose limitations in clinical practice. Advances in knowledge: The diagnostic image quality of postprocessed skeletal radiographs is not significantly impaired even after extensive dose reduction by up to 20% of the reference value

68Ga-PSMA-PET/CT for the evaluation of liver metastases in patients with prostate cancer

BACKGROUND: The purpose of this study was to evaluate the imaging properties of hepatic metastases in 68Ga-PSMA positron emission tomography (PET) in patients with prostate cancer (PC). METHODS: 68Ga-PSMA-PET/CT scans of PC patients available in our database were evaluated retrospectively for liver metastases. Metastases were identified using 68Ga-PSMA-PET, CT, MRI and follow-up scans. Different parameters including, maximum standardized uptake values (SUVmax) of the healthy liver and liver metastases were assessed by two- and three-dimensional regions of interest (2D/3D ROI). RESULTS: One hundred three liver metastases in 18 of 739 PC patients were identified. In total, 80 PSMA-positive (77.7%) and 23 PSMA-negative (22.3%) metastases were identified. The mean SUVmax of PSMA-positive liver metastases was significantly higher than that of the normal liver tissue in both 2D and 3D ROI (p ≤ 0.05). The mean SUVmax of PSMA-positive metastases was 9.84 ± 4.94 in 2D ROI and 10.27 ± 5.28 in 3D ROI; the mean SUVmax of PSMA-negative metastases was 3.25 ± 1.81 in 2D ROI and 3.40 ± 1.78 in 3D ROI, and significantly lower than that of the normal liver tissue (p ≤ 0.05). A significant (p ≤ 0.05) correlation between SUVmax in PSMA-positive liver metastases and both size (ρSpearman = 0.57) of metastases and PSA serum level (ρSpearman = 0.60) was found. CONCLUSIONS: In 68Ga-PSMA-PET, the majority of liver metastases highly overexpress PSMA and is therefore directly detectable. For the analysis of PET images, it has to be taken into account that also a significant portion of metastases can only be detected indirectly, as these metastases are PSMA-negative

Discrepancy of echocardiography and computed tomography in initial assessment and 2-year follow-up for monitoring Marfan syndrome and related disorders

Patients with Marfan syndrome and related disorders are at risk for aortic dissection and aortic rupture and therefore require appropriate monitoring. Computed tomography (CT) and transthoracic echocardiography (TTE) are routinely used for initial diagnosis and follow-up. The purpose of this study is to compare whole-heart CT and TTE aortic measurement for initial work-up, 2-year follow-up, and detection of progressive aortic enlargement. This retrospective study included 95 patients diagnosed with Marfan syndrome or a related disorder. All patients underwent initial work-up including aortic diameter measurement using both electrocardiography-triggered whole-heart CT and TTE. Forty-two of these patients did not undergo aortic repair after initial work-up and were monitored by follow-up imaging within 2 years. Differences between the two methods for measuring aortic diameters were compared using Bland-Altman plots. The acceptable clinical limit of agreement (acLOA) for initial work-up, follow-up, and progression within 2 years was predefined as < +/- 2 mm. Bland-Altman analysis revealed a small bias of 0.2 mm with wide limits of agreement (LOA) from + 6.3 to - 5.9 mm for the aortic sinus and a relevant bias of - 1.6 mm with wide LOA from + 5.6 to - 8.9 mm for the ascending aorta. Follow-up imaging yielded a small bias of 0.5 mm with a wide LOA from + 6.7 to - 5.8 mm for the aortic sinus and a relevant bias of 1.1 mm with wide LOA from + 8.1 to - 10.2 mm for the ascending aorta. Progressive aortic enlargement at follow-up was detected in 57% of patients using CT and 40% of patients using TTE. Measurement differences outside the acLOA were most frequently observed for the ascending aorta. Whole-heart CT and TTE measurements show good correlation, but the frequency of measurement differences outside the acLOA is high. TTE systematically overestimates aortic diameters. Therefore, whole-heart CT may be preferred for aortic monitoring of patients with Marfan syndrome and related disorders. TTE remains an indispensable imaging tool that provides additional information not available with CT

Left atrial diverticulum - An unexpected finding in routine transesophageal echocardiography

We report a 55-year-old male patient with lone paroxysmal atrial fibrillation who underwent routine transesophageal echocardiography (TOE) at our institution. In a mid-esophageal 125 degrees three-chamber angulation, a distinct thinning of the left atrial (LA) wall was observed, forming a 7 x 4 mm canal with only a small membrane separating the LA from the pericardial space. Cardiac magnetic resonance imaging diagnosed a small LA diverticulum. To the best of our knowledge, this is the first manuscript describing detection of a small LA diverticulum via TOE

Tablets as an Option for Telemedicine—Evaluation of Diagnostic Performance and Efficiency in Intracranial Arterial Aneurysm Detection

Purpose: To evaluate a commercially available mobile device for the highly specialized task of detection of intracranial arterial aneurysm in telemedicine. Methods: Six radiologists with three different levels of experience retrospectively interpreted 60 computed tomography (CT) angiographies for the presence of intracranial arterial aneurysm, among them 30 cases with confirmed positive findings. Each radiologist reviewed the angiography datasets twice: once on a dedicated medical-grade workstation and on a commercially available mobile consumer-grade tablet with an interval of 3 months. Diagnostic performance, reading efficiency and subjective scorings including diagnostic confidence were analyzed and compared. Results: Diagnostic performance was comparable on both devices regardless of readers' experience, and no significant differences in sensitivity (66-87.5%) and specificity (79.4-87%) were found. Results obtained with tablets and medical workstations were also comparable in terms of subjective assessment across all reader groups. Conclusions: There was no significant difference between tablet and workstation readings of angiography datasets for the presence of intracranial arterial aneurysm. Sensitivity, specificity, efficiency and subjective scorings were similar with the two devices for all three reader groups. While medical workstations are 10 times more expensive, tablets allow higher mobility especially for radiologists on call

HBP-enhancing hepatocellular adenomas and how to discriminate them from FNH in Gd-EOB MRI

BackgroundRecent studies provide evidence that hepatocellular adenomas (HCAs) frequently take up gadoxetic acid (Gd-EOB) during the hepatobiliary phase (HBP). The purpose of our study was to investigate how to differentiate between Gd-EOB-enhancing HCAs and focal nodular hyperplasias (FNHs). We therefore retrospectively included 40 HCAs classified as HBP Gd-EOB-enhancing lesions from a sample of 100 histopathologically proven HCAs in 65 patients. These enhancing HCAs were matched retrospectively with 28 FNH lesions (standard of reference: surgical resection). Two readers (experienced abdominal radiologists blinded to clinical data) reviewed the images evaluating morphologic features and subjectively scoring Gd-EOB uptake (25-50%, 50-75% and 75-100%) for each lesion. Quantitative lesion-to-liver enhancement was measured in arterial, portal venous (PV), transitional and HBP. Additionally, multivariate regression analyses were performed. ResultsSubjective scoring of intralesional Gd-EOB uptake showed the highest discriminatory accuracies (AUC: 0.848 (R#1); 0.920 (R#2)-p0.05). ConclusionEven in HBP-enhancing HCA, characterization of Gd-EOB uptake was found to provide the strongest discriminatory power in differentiating HCA from FNH. Furthermore, a lobulated appearance and a central scar are more frequently seen in FNH than in HCA

PET measured hypoxia and MRI parameters in re-irradiated head and neck squamous cell carcinomas: findings of a prospective pilot study [version 2; peer review: 2 approved]

Background: Tumor hypoxia measured by dedicated tracers like [ 18F]fluoromisonidazole (FMISO) is a well-established prognostic factor in head and neck squamous cell carcinomas (HNSCC) treated with definitive chemoradiation (CRT). However, prevalence and characteristics of positron emission tomography (PET) measured hypoxia in patients with relapse after previous irradiation is missing. Here we report imaging findings of a prospective pilot study in HNSCC patients treated with re-irradiation. Methods: In 8 patients with recurrent HNSCC, diagnosed at a median of 18 months after initial radiotherapy/CRT, [ 18F]fluorodeoxyglucose (FDG)-PET/CT (n=8) and FMISO-PET/MRI (n=7) or FMISO-PET/CT (n=1) were performed. Static FMISO-PET was performed after 180 min. MRI sequences in PET/MRI included diffusion-weighted imaging with apparent diffusion coefficient (ADC) values and contrast enhanced T1w imaging (StarVIBE). Lesions (primary tumor recurrence, 4; cervical lymph node, 1; both, 3) were delineated on FDG-PET and FMISO-PET data using a background-adapted threshold-based method. SUV max and SUV mean in FDG- and FMISO-PET were derived, as well as maximum tumor-to-muscle ratio (TMR max) and hypoxic volume with 1.6-fold muscle SUV mean (HV 1.6) in FMISO-PET. Intensity of lesional contrast enhancement was rated relative to contralateral normal tissue. Average ADC values were derived from a 2D region of interest in the tumor. Results: In FMISO-PET, median TMR max was 1.7 (range: 1.1-1.8). Median HV 1.6 was 0.05 ml (range: 0-7.3 ml). Only in 2/8 patients, HV 1.6 was ≥1.0 ml. In FDG-PET, median SUV max was 9.3 (range: 5.0-20.1). On contrast enhanced imaging four lesions showed decreased and four lesions increased contrast enhancement compared to non-pathologic reference tissue. Median average ADC was 1,060 ×10 6 mm 2/s (range: 840-1,400 ×10 6 mm 2/s). Conclusions: This pilot study implies that hypoxia detectable by FMISO-PET may not be as prevalent as expected among loco-regional recurrent, HPV negative HNSCC. ADC values were only mildly reduced, and contrast enhancement was variable. The results require confirmation in larger sample sizes

Wearable cardioverter‐defibrillator: friend or foe in suspected myocarditis?

Aim: Wearable cardioverter defibrillator (WCD, LifeVest, and Zoll) therapy has become a useful tool to bridge a temporarily increased risk for sudden cardiac death. However, despite extensive use, there is a lack of evidence whether patients with myocarditis and impaired LVEF may benefit from treatment with a WCD. Methods and results: We conducted a single-centre retrospective observational study analysing patients with a WCD prescribed between September 2015 and April 2020 at our institution. In total, 135 patients were provided with a WCD, amongst these 76 patients (mean age 48.9 +/- 13.7 years; 84.2% male) for clinically suspected myocarditis. Based on the results of the endomyocardial biopsy and, where available cardiac magnetic resonance imaging, 39 patients (51.3%) were diagnosed with myocarditis and impaired LVEF and 37 patients (48.7%) with dilated cardiomyopathy (DCM) without evidence of cardiac inflammation. The main immunohistopathological myocarditis subtype was lymphocytic myocarditis in 36 (92.3%) patients, and four patients (10.3%) of this group had an acute myocarditis. Three patients had cardiac sarcoidosis (7.7%). Ventricular tachycardia occurred in seven myocarditis (in total 41 VTs; 85.4% non-sustained) and one DCM patients (in total one non-sustained ventricular tachycardia). Calculated necessary WCD wearing time until ventricular tachycardia occurrence is 86.41 days in myocarditis compared with 6.46 years in DCM patients. Conclusions: Our data suggest that myocarditis patients may benefit from WCD therapy. However, as our study is not powered for outcome, further randomized studies powered for the outcome morbidity and mortality are necessary

Shortened Tracer Uptake Time in GA-68-DOTATOC-PET of Meningiomas Does Not Impair Diagnostic Accuracy and PET Volume Definition

Ga-68-DOTATOC-PET/MRI can affect the planning target volume (PTV) definition of meningiomas before radiosurgery. A shorter tracer uptake time before image acquisition could allow the examination of more patients. The aim of this study was to investigate if shortening uptake time is possible without compromising diagnostic accuracy and PET volume. Fifteen patients (f = 12; mean age 52 years (34-80 years)) with meningiomas were prospectively examined with dynamic [68Ga]Ga-68-labeled [DOTA0-Phe1-Tyr3] octreotide (Ga-68-DOTATOC)-PET/MRI over 70 min before radiosurgery planning. Meningiomas were delineated manually in the PET dataset. PET volumes at each time point were compared to the reference standard 60 min post tracer injection (p.i.) using the Friedman test followed by a Wilcoxon signed-rank test and Bonferroni correction. In all patients, the earliest time point with 100% lesion detection compared to 60 min p.i. was identified. PET volumes did not change significantly from 15 min p.i. (p = 1.0) compared to 60 min p.i. The earliest time point with 100% lesion detection in all patients was 10 min p.i. In patients with meningiomas undergoing Ga-68-DOTATOC-PET, the tracer uptake time can safely be reduced to 15 min p.i. with comparable PET volume and 100% lesion detection compared to 60 min p.i

evaluation of MR-thermometry in vitro

Die Perkutane Laser Diskus Dekompression (PLDD) kommt, als minimal-invasive Therapie für Bandscheibenvorfälle, in der klinischen Praxis vermehrt zum Einsatz. Neue offene Hochfeld-MRT-Systeme ermöglichen heute eine hohe Bildqualität, schnelle Sequenzen und die Option, Interventionen unter MRT- Kontrolle durchzuführen. Material und Methoden: In dieser Arbeit wurde in präklinischen Versuchen, die Durchführbarkeit der PLDD im offenen Hochfeld MRT und die MR-Thermometrie an der Bandscheibe in vitro untersucht und optimiert. Zunächst wurde die MR-Tauglichkeit des Lasers, der Punktionsnadeln und verschiedener MR-fluoroskopischer Sequenzen an 10 Schweinewirbelsäulen gezeigt. Anschließend wurden GRE Sequenzen mit unterschiedlichen TE-Zeiten, mit Hinblick auf die PRF-Thermometrie, an 30 Humankadaverbandscheiben (L1-S1) untersucht. Eine Korrelation der MR-thermometrisch kalkulierten und der tatsächlich gemessenen Temperaturen diente zur Beurteilung der jeweiligen Sequenzen. Ergebnisse: Temperaturkorrelationskoeffizienten: 0,946 (TE 7 ms) vergl. 0,859 (TE = 2 ms) und 0,792 (TE = 10ms mit ES); CNRDiskus/Endplatte/CNRDiskus/Spinalnerv/CNRDiskus/Muskel/CNRDiskus/Nadel: 14,3 ± 12,0 (n=10)/10,8 ± 7,5 (n=8)/16,3 ± 11,8 (n=10)/25,5 ± 12,7 (n=10) für die GRE mit TE = 7ms im Vergleich zu 11,6 ± 11,4 (n=10)/13,1 ± 12,8 (n=10)/22,7 ± 14,7 (n=10)/21,5 ± 17,4 (n=10) für die GRE mit TE = 2ms und 6,8 ± 4,6 (n=10)/n=0 /17,5 ± 7,3 (n=10)/20,6 ± 8,9 (n=10) für die GRE mit TE = 10ms mit ES. Korrelation der MR-Läsionen mit den makroskopischen Befunden: R2 = 0,63 (TE =7 ms); R2 = 0,76 (TE = 2ms) und R2 = 0,48 (TE = 10 ms mit ES). Im statistischen Vergleich korrelierten jene Temperaturverläufe, welche anhand der GRE mit TE = 7ms berechnet wurden, signifikant (p < 0,05) besser mit der tatsächlichen Temperatur, als die GRE mit ES und TE = 10 ms (p = 0,001). Eine statistisch relevante Überlegenheit gegenüber der GRE mit TE = 2ms konnte nicht belegt werden (p = 0,064). Die Auswertung ergab, dass die eine ungespoilte GRE Sequenz mit einer TE von 7ms (3D GRE TR/TE/FA 10/7/27°, 15 Schichten, Scandauer 13,1s pro Bild) im Vergleich zu den anderen evaluierten Sequenzen (3D GRE TR/TE/FA 4,2/2/27°, 15 Schichten, Scandauer 13,2 s; 3D GRE mit ES TR/TE/FA 6,8/10/35°, 15 Schichten, Scandauer 12,5 s), die beste Korrelation zwischen gemessener und kalkulierter Temperatur erzielte und den besten Kompromiss zwischen einer möglichst genauen PRF-Thermometrie und einer möglichst hohen Qualität der Magnitudenbilder darstellte. Diskussion: Die PRF- Thermometrie wird heute in der klinischen Praxis bereits für die Kontrolle hyperthermer Therapien an Prostata und Uterus eingesetzt. Eine PRF- Thermometrie an der Bandscheibe wurde bis dato nicht evaluiert. Mit dieser Arbeit konnte erfolgreich die Grundlage für eine klinische Etablierung der PLDD im offenen Hochfeld MRT unter MR-thermometrischer Kontrolle geschaffen werden. Die beste Sequenz hierfür war, unter den Vorraussetzungen des offenen Hochfeld MRT mit vertikalem Magnetfeld, eine ungespoile GRE Sequenz mit einer TE-Zeit von 7 ms und einem Flipwinkel von 27°.Percutaneous Laser Disc Decompression (PLDD) is becoming increasingly popular in the treatment of vertebral disc protrusions. New open high-field systems permit high image quality, fast sequences and the option to perform interventions under MR-guidance. Materials and methods: With this study the feasibility of PLDD under MR-thermometry in an open high-field MRI was investigated in preclinical experiments in vitro. First, the MR-compatibility of the Laser, the puncture needles and various fluoroscopic sequences was demonstrated on 10 porcine lumbar spines. Hereafter, GRE sequences with varying TE-times were evaluated with respect to PRF-thermometry on 30 human cadaveric lumbar discs (L1-S1). Correlation and regression analysis of MR- thermometrically calculated and the actually measured temperatures were performed to assess each investigated sequence. Results: Temperature correlation coefficients: 0.946 (TE 7 ms) compared to 0.859 (TE = 2 ms) and 0,792 (TE = 10ms and ES); CNRDiskus/Endplatte/CNRDiskus/Spinalnerv/CNRDiskus/Muskel/CNRDiskus/Nadel: 14.3 ± 12.0 (n=10)/10.8 ± 7.5 (n=8)/16.3 ± 11.8 (n=10)/25.5 ± 12.7 (n=10) for GRE sequence with TE = 7ms compared to 11.6 ± 11.4 (n=10)/13.1 ± 12,8 (n=10)/22.7 ± 14,7 (n=10)/21.5 ± 17.4 (n=10) for GRE sequence with TE = 2ms and 6.8 ± 4.6 (n=10)/n=0 /17.5 ± 7.3 (n=10)/20.6 ± 8.9 (n=10) for GRE sequence with TE = 10ms and ES. Correlation of MR-lesions with macroscopic findings upon regression analysis: R2 = 0.63 (TE =7 ms); R2 = 0.76 (TE = 2ms) und R2 = 0.48 (TE = 10 ms and ES). Upon statistical comparison with temperature data from the GRE with TE = 10ms and ES, those temperature curves calculated from the GRE sequence with TE = 7ms were more precise (p = 0.001). A statistically relevant (p < 0.05) superiority of the GRE with TE = 7ms compared to the GRE with TE = 2ms could not be shown (p = 0.064). In summary, the unspoiled GRE with TE = 7ms (3D GRE TR/TE/FA 10/7/27°, 15 slices, scan duration 13,1s per image) was shown to have the best temperature correlation with actually measured temperatures and proved to best he best compromise between precise PRF-thermometry and high image quality of magnitude images compared to the other two investigated GRE sequences (3D GRE TR/TE/FA 4,2/2/27°, 15 slices, scan duration 13,2 s and 3D GRE and ES TR/TE/FA 6,8/10/35°, 15 slices, scan duration 12,5 s). Discussion: PRF-thermometry is in clinical use today for hyperthermal treatment of the prostate and the uterus. To date, PRF- thermometry to monitor interventions in the intervertebral disc has not been investigated. With this study, the basis for clinical application and implementation of MR-thermometrically monitored PLDD in the open high-field MRI was provided. An unspoiled GRE sequence with TE = 7ms and a flip angle of 27° was deemed to be the best fit for this purpose