Feasibility and diagnostic accuracy of fast whole-body MRI in slightly to moderately injured trauma patients.

OBJECTIVES: To determine the feasibility and diagnostic accuracy of fast whole-body magnetic resonance imaging (WB-MRI) compared to whole-body computed tomography (WB-CT) in detecting injuries of slightly to moderately injured trauma patients. MATERIALS AND METHODS: In a prospective single-center approach, trauma patients from convenience sampling with an expected Abbreviated Injury Scale (AIS) score ≤ 3 at admission, received an indicated contrast-enhanced WB-CT (reference standard) and a plain WB-MRI (index test) voluntarily up to five days after trauma. Two radiologists, blinded to the WB-CT findings, evaluated the absence or presence of injuries with WB-MRI in four body regions: head, torso, axial skeleton, and upper extremity. Diagnostic accuracy was determined using sensitivity, specificity, positive predictive value, and negative predictive value by body region. RESULTS: Between June 2019 and July 2021, 40 patients were assessed for eligibility of whom 35 (median age (interquartile range): 50 (32.5) years; 26 men) received WB-MRI. Of 140 body regions (35 patients × 4 regions), 31 true positive, 6 false positive, 94 true negative, and 9 false negative findings were documented with WB-MRI. Thus, plain WB-MRI achieved a total sensitivity of 77.5% (95%-confidence interval (CI): (61.6-89.2%)), specificity of 94% (95%-CI: (87.4-97.8%)), and diagnostic accuracy of 89.3% (95%-CI: (82.9-93.9%)). Across the four regions sensitivity and specificity varied: head (66.7%/93.1%), torso (62.5%/96.3%), axial skeleton (91.3%/75%), upper extremity (33.3%/100%). Both radiologists showed substantial agreement on the WB-MRI reading (Cohen's Kappa: 0.66, 95%-CI: (0.51-0.81)). CONCLUSION: Regarding injury detection, WB-MRI is feasible in slightly to moderately injured trauma patients, especially in the axial skeleton. CLINICAL RELEVANCE STATEMENT: Besides offering a radiation-free approach, whole-body MRI detects injuries almost identically to whole-body CT in slightly to moderately injured trauma patients, who comprise a relevant share of all trauma patients. KEY POINTS: Whole-body MRI could offer radiation-free injury detection in slightly to moderately injured trauma patients. Whole-body MRI detected injuries almost identically compared to whole-body CT in this population. Whole-body MRI could be a radiation-free approach for slightly to moderately injured young trauma patients.

Safety and efficacy of Holmium-166 selective internal radiotherapy of primary and secondary liver cancer confirmed by real-world data.

Purpose: Holmium-166 has emerged as a promising option for selective internal radiotherapy (SIRT) for hepatic malignancies, but data on routine clinical use are lacking. The purpose of this study was to describe the safety and effectiveness of Holmium-166 SIRT in real-world practice through retrospective analysis of a multicenter registry. Methods: Retrospective analysis was conducted on Holmium-166 SIRT procedures performed between July 15, 2019, and July 15, 2021, across seven European centers. Treatment planning, treatment realization and post-treatment follow-up were conducted according to routine local practice. Safety and effectiveness data were extracted from the patients' health records. Primary endpoint analysis was assessed for the entire study population with separate analysis for subgroups with hepatocellular carcinoma, metastatic colorectal cancer and intrahepatic cholangiocarcinoma. Results: A total of 167 SIRT procedures in 146 patients (mean age 66 ± 11 years, 68% male) were retrospectively evaluated. Most common tumor entities were hepatocellular carcinoma (n=55), metastatic colorectal cancer (n=35), intrahepatic cholangiocarcinoma (n=19) and metastatic neuroendocrine tumors (n=10). Nine adverse events grade ≥ 3 according to Common Terminology Criteria for Adverse Events were recorded, including one fatal case of radioembolization-induced liver disease. Response rates and median overall survival for the above mentioned subgroups were comparable to results from previous Holmium-166 trials as well as to results from Yttrium-90 registries. Conclusion: This study confirms that the safety and effectiveness of Holmium-166 SIRT derived from prospective trials also applies in routine clinical practice, reinforcing its potential as a viable treatment option for primary and secondary liver cancer.

Midterm survival after aortic repair versus conservative treatment in patients with penetrating aortic ulcer.

Background: The clinical outcomes and survival of patients with penetrating aortic ulcers (PAU) were evaluated in a tertiary care hospital, comparing those who underwent aortic repair to those treated conservatively. Patients and methods: A retrospective single-centre analysis included all patients that underwent a computed tomography angiography (CT-A) scan with the diagnosis of a PAU between January 2009 and May 2019. "PAU" was identified in 1,493 of 112,506 CT-A scan reports in 576 patients. Clinical and angiomorphological data were collected. The primary outcome was overall survival (OS), with secondary outcomes focusing on identifying risk factors for poor OS. Survival probabilities were analysed by the Kaplan-Meier method using the log-rank test. A Cox hazard model using survival as dependent variable with stepwise backward eliminations based on the likelihood ratios was employed. Results: 315 PAUs were identified in 278 patients. The prevalence in the cohort was 0.8%. The mean age of the patients was 74.4 years, and they were predominantly male (n = 208, 74.8%). The mean ulcer depth was 11.8 mm (range 2-50 mm). Out of the patients, 232 were asymptomatic (83.5%). Among 178 PAUs (56.5%), high-risk factors, such as ulcer depth >10 mm, aortic diameter >40 mm, and ulcer length >20 mm, were observed. Aortic repair was associated with a better mean OS compared to conservatively managed patients (72.6 versus 32.2 months, p = 0.001). The Cox hazard model showed that ulcer depth >1 mm was associated with poor OS (HR 0.67, p = 0.048), while aortic repair was related to a better OS (HR 4.365, p<0.013). Conclusions: Aortic repair is associated with better OS, but this finding should be interpreted with caution because of differences in age and comorbidities between the groups. Further evaluation is warranted through prospective studies with randomized groups. Further assessment for angiomorphological parameters is recommended to identify patients at increased risk for poor OS.

The status of academic interventional radiologists in Germany with focus on gender disparity: how can we do better?

PURPOSE: The aim was to characterize the framework conditions in academic interventional radiology (IR) in Germany with focus on differences between genders. MATERIALS AND METHODS: After IRB approval, all members of The German Society for Interventional Radiology and Minimally Invasive Therapy (n = 1,632) were invited to an online survey on work and research. Statistical comparisons were undertaken with the Fisher's exact test, Wilcoxon rank sum test or Pearson's Chi-squared test. RESULTS: From 267 available questionnaires (general response rate 16.4%), 200 were fully completed. 40% of these (78/200) were involved in research (71% men vs. 29% women, p < 0.01) and eligible for further analysis. Of these, 6% worked part-time (2% vs. 17%, p < 0.05). 90% of the respondents spent less than 25% of their research during their paid working hours, and 41% performed more than 75% of their research during. leisure time. 28% received exemption for research. 88% were (rather) satisfied with their career. One in two participants successfully applied for funding, with higher success rates among male applicants (90% vs. 75%) and respondents with protected research time (93% vs. 80%). Compared to men, women rated their entrance in research as harder (p < 0.05), their research career as more important (p < 0.05), felt less noticed at congresses (93% vs. 53%, p < 0.01), less confident (98% vs. 71%, p < 0.01), and not well connected (77% vs. 36%, p < 0.01).  CONCLUSION: Women and men did research under the same circumstances; however, women were underrepresented. Future programs should generally focus on protected research time and gather female mentors to advance academic IR in Germany.

Outcome of Endovascular and Open Treated Penetrating Aortic Ulcers.

PURPOSE: Penetrating aortic ulcer (PAU) is a rare etiology of acute aortic syndrome. Few studies exist regarding the perioperative outcome. The aim was to analyze clinical outcome and risk factors of mortality in this treatment population. METHODS: Retrospective, monocentric study from 2010 to 2021. Clinical data of endovascular or open treated PAU were analyzed. In-hospital mortality was selected as the primary study endpoint. Angio-morphologies were analyzed and risk factors for mortality were identified by using univariate analysis. RESULTS: Overall, 133 patients were identified. 29% (n=38) of patients presented symptomatically. In 64% (n=85), the PAU was localized in the thoracic aorta. On average, PAUs had a depth of 15.4±10.1 mm and a width of 17.9±9.6 mm. The patients had a median of 2 (95% confidence interval [CI]=2-3) high-risk features (HRF) as PAU depth >10 mm, PAU width >20 mm, aortic diameter >40 mm, symptomatic, intramural hematoma (IMH), pleural effusion. Significantly more HRF were observed in symptomatic patients (p=0.01). 53% (n=71) of patients were treated with thoracic endovascular aortic repair (TEVAR), 41% (n=54) by endovascular aortic repair (EVAR), and 6% (n=8) by open surgery. A hybrid procedure with cervical debranching was performed in 16% (n=21) and complex endovascular repair with fenestrated or branched endografts in 15% (n=20). Overall, complications greater than grade II according to the Clavien-Dindo classification occurred in 19% (n=25) and of the patients. In-hospital mortality manifested in 6% (n=8). Factors associated with increased mortality were the diameter of the aorta >40 mm (88% vs 39%, p=0.03), as well as symptomatic patients (63% vs 26%, p=0.04), coincident IMHs (38% vs 10%, p=0.05), and complex endovascular procedures (50% vs 50% p<0.01). Penetrating aortic ulcer width >20 mm tended to show higher mortality (75% vs 40%, p=0.06). Routine follow-up was available for 89% (n=117) for a median of 39 months (95% CI=25-42). One-year and 5-year survival were 83% and 60%, respectively, with 1 aortic pathology-related death. CONCLUSIONS: Treatment of PAU is associated with an acceptable perioperative morbidity and mortality. Risk factors associated with increased mortality are an elevated aortic diameter, the presence of IMHs, clinical symptomatology at presentation, and complex endovascular procedures.

Comparative analysis of radiomics and deep-learning algorithms for survival prediction in hepatocellular carcinoma.

To examine the comparative robustness of computed tomography (CT)-based conventional radiomics and deep-learning convolutional neural networks (CNN) to predict overall survival (OS) in HCC patients. Retrospectively, 114 HCC patients with pretherapeutic CT of the liver were randomized into a development (n = 85) and a validation (n = 29) cohort, including patients of all tumor stages and several applied therapies. In addition to clinical parameters, image annotations of the liver parenchyma and of tumor findings on CT were available. Cox-regression based on radiomics features and CNN models were established and combined with clinical parameters to predict OS. Model performance was assessed using the concordance index (C-index). Log-rank tests were used to test model-based patient stratification into high/low-risk groups. The clinical Cox-regression model achieved the best validation performance for OS (C-index [95% confidence interval (CI)] 0.74 [0.57-0.86]) with a significant difference between the risk groups (p = 0.03). In image analysis, the CNN models (lowest C-index [CI] 0.63 [0.39-0.83]; highest C-index [CI] 0.71 [0.49-0.88]) were superior to the corresponding radiomics models (lowest C-index [CI] 0.51 [0.30-0.73]; highest C-index [CI] 0.66 [0.48-0.79]). A significant risk stratification was not possible (p > 0.05). Under clinical conditions, CNN-algorithms demonstrate superior prognostic potential to predict OS in HCC patients compared to conventional radiomics approaches and could therefore provide important information in the clinical setting, especially when clinical data is limited.

Avoiding adverse events in interventional radiology - a systematic review on the instruments.

BACKGROUND: Avoiding AEs is a pivotal fundament for high patient safety in an efficient interventional radiology (IR) department. Although IR procedures are considered to have a lower risk than their surgical alternatives, they account for one third of all radiological adverse events (AEs) and in general, the number of AEs is increasing. Thus, measures to prevent AEs in IR are of interest. METHODS: A systematic literature search was conducted via handsearch and Ovid. A structured data extraction was performed with all included studies and their quality of evidence was evaluated. Finally, data were aggregated for further statistical analysis. RESULTS: After screening 1,899 records, 25 full-text publications were screened for eligibility. Nine studies were included in the review. Of those, four studies investigated in simulator training, one in team training, three in checklists, and one in team time-out. Eight were monocenter studies, and five were conducted in a non-clinical context. Study quality was low. Aggregation and analysis of data was only possible for the studies about checklists with an overall reduction of the median error per procedure from 0.35 to 0.06, observed in a total of 20,399 and 58,963 procedures, respectively. CONCLUSION: The evidence on the instruments to avoid AEs in IR is low. Further research should be conducted to elaborate the most powerful safety tools to improve patient outcomes in IR by avoiding AEs.

Outcome After Conservative and Endovascular Treatment of Stanford Type B Aortic Intramural Hematomas - A Single-Center Retrospective Study.

OBJECTIVES: Aortic intramural hematoma (IMH) is a rare disease. Thus far, only limited data is available and the indications for conservative and endovascular treatment are not well defined. The aim of this study was to investigate clinical presentation, course, CT imaging features and outcome of patients with type B aortic IMHs. METHODS: We included all patients with type B IMHs between 2012 and 2021 in this retrospective monocentric study. Clinical data, localization, thickness of IMHs and the presence of ulcer-like projections (ULPs) was evaluated before and after treatment. RESULTS: Thirty five patients (20 females; 70.3 y ± 11 y) were identified. Almost all IMHs (n = 34) were spontaneous and symptomatic with back pain (n = 34). At the time of diagnosis, TEVAR was deemed indicated in 9 patients, 26 patients were treated primarily conservatively. During the follow-up, in another 16 patients TEVAR was deemed indicated. Endovascularly and conservatively treated patients both showed decrease in thickness after treatment. Patients without ULPs showed more often complete resolution of the IMH than patients with ULPs (endovascularly treated 90.9% (10/11) vs 71.4% (5/7); conservatively treated 71.4% (10/14) vs 33.3% (1/3); P = .207). Complications after TEVAR occurred in 32% and more frequently in patients treated primarily conservatively (37.5% vs 22.2%). No in-hospital mortality was observed during follow-up. CONCLUSIONS: Prognosis of IMH seems favourable in both surgically as well as conservatively treated patients. However, it is essential to identify patients at high risk for complications under conservative treatment, who therefore should be treated by TEVAR. In our study, ULPs seem to be an adverse factor for remodeling.

CT versus MR guidance for radiofrequency ablation in patients with colorectal liver metastases: a 10-year follow-up favors MR guidance.

OBJECTIVES: To compare the results of CT- vs MR-guided radiofrequency ablation (RFA) of liver metastases (LM) from colorectal cancer after 10 years of follow-up in an observational, retrospective, and multicentric study. METHODS: A total of 238 patients with 496 LM were treated with RFA either with CT (CT group) or magnetic resonance (MR group) guidance. Every ablated LM was assessed and followed up with diagnostic MRI. Technical success, technique efficacy, predictive factors, recurrence rates, and overall survival were assessed. RESULTS: The CT group comprised 143 patients and the MR group 77 patients. Eighteen patients underwent ablation with both modalities. Technical success per patient and per lesion was 88% and 93% for CT and 87% and 89.6% for MR, and technique efficacy was 97.1% and 98.6% for CT and 98.7% and 99.3% for MR respectively. Local recurrence following the first ablation (primary patency) occurred in 20.1% (CT) vs 4.6% (MR) (p < 0.001). Residual liver tumor, size of LM, and advanced N and M stage at initial diagnosis were independent predictors for overall survival in both groups. The median overall survival measured from first RFA treatment was 2.6 years. The 1-year, 5-year, and 10-year survival were 85.9%, 25.5%, and 19.1% respectively. CONCLUSIONS: The MR group had significantly better local control compared to the CT group. There was no significant difference in patient survival between the two groups. CLINICAL RELEVANCE STATEMENT: MR-guided radiofrequency ablation of colorectal liver metastases is safe and effective, and offers better local control than CT-guided ablation. KEY POINTS: • Imaging modality for radiofrequency ablation guidance is an independent predictor of local recurrence in colorectal liver metastases. • MR-guided radiofrequency ablation achieved better local control of liver metastases from colorectal cancer than CT-guided. • The number and size of liver metastases are, among others, independent predictors of survival. Radiofrequency ablation with MR guidance improved clinical outcome but does not affect survival.

Effect of Contrast Timing, Volume, and Flow Rate on Image Quality of Pulmonary Arteries in CTA.

PURPOSE: To evaluate the effect of contrast timing, contrast volume, and contrast flow rate on the image quality of pulmonary arteries in computed tomography angiography (CTA) and to assess if bolus-tracking region of interest (ROI) positioning in the left atrium, which is used for triple-rule-out CTA, allows for sufficient depiction of the pulmonary arteries. METHODS: In this retrospective single-center study, data were collected for patients who underwent thoracic CTA during a specific period. Two groups of 121 patients each were created based on bolus-tracking ROI positioning in the main pulmonary artery or left atrium using propensity score matching. Image quality of the pulmonary arteries was evaluated using quantitative and qualitative scores. Subgroups were formed to examine the influence of contrast volume and flow rate. Two radiologists determined if pulmonary embolism was present, if pulmonary embolism could be excluded with certainty, and from which level pulmonary embolism could be excluded with certainty. Interrater reliability also was evaluated. RESULTS: ROI positioning in the main pulmonary artery scored significantly higher compared with the left atrium. There was no significant difference in subgroups of patients who were examined with 60 mL or more contrast volume and less than 4 mL/s flow rate; scores were similar or better than in the overall study population. Pulmonary embolism was not able to be excluded with certainty for each 1 patient in these subgroups compared with a high percentage in the overall study population. DISCUSSION: ROI positioning in the left atrium in combination with the 60 mL or more contrast volume and less than 4 mL/s flow rate does not adversely affect depiction of the pulmonary arteries compared with conventional ROI positioning in the main pulmonary artery. CONCLUSION: When using 60 mL or more contrast volume and less than 4 mL/s flow rate, ROI positioning in the left atrium, which is used in triple-rule-out CTA, is sufficient for the assessment of pulmonary arteries.

Prediction of clinically relevant postoperative pancreatic fistula using radiomic features and preoperative data.

Clinically relevant postoperative pancreatic fistula (CR-POPF) can significantly affect the treatment course and outcome in pancreatic cancer patients. Preoperative prediction of CR-POPF can aid the surgical decision-making process and lead to better perioperative management of patients. In this retrospective study of 108 pancreatic head resection patients, we present risk models for the prediction of CR-POPF that use combinations of preoperative computed tomography (CT)-based radiomic features, mesh-based volumes of annotated intra- and peripancreatic structures and preoperative clinical data. The risk signatures were evaluated and analysed in detail by visualising feature expression maps and by comparing significant features to the established CR-POPF risk measures. Out of the risk models that were developed in this study, the combined radiomic and clinical signature performed best with an average area under receiver operating characteristic curve (AUC) of 0.86 and a balanced accuracy score of 0.76 on validation data. The following pre-operative features showed significant correlation with outcome in this signature ([Formula: see text]) - texture and morphology of the healthy pancreatic segment, intensity volume histogram-based feature of the pancreatic duct segment, morphology of the combined segment, and BMI. The predictions of this pre-operative signature showed strong correlation (Spearman correlation co-efficient, [Formula: see text]) with the intraoperative updated alternative fistula risk score (ua-FRS), which is the clinical gold standard for intraoperative CR-POPF risk stratification. These results indicate that the proposed combined radiomic and clinical signature developed solely based on preoperatively available clinical and routine imaging data can perform on par with the current state-of-the-art intraoperative models for CR-POPF risk stratification.

Impact of the COVID-19 pandemic on therapeutic interventional oncology procedures and diagnostic CT/MRI examinations at a German university hospital.

PURPOSE: The COVID-19 pandemic led to the implementation of severe restrictions on public life in Germany and a reduction in the number of non-COVID patients presenting for care. The aim of this study was to measure the impact on the number of therapeutic interventional oncology procedures in relation to diagnostic imaging studies at a high-volume radiology department. MATERIALS AND METHODS: The numbers of therapeutic interventional oncology procedures and diagnostic CT/MRI examinations for the years 2010 to 2021 were extracted using the hospital information system. Monthly data from January 2010 to December 2019 were used to build forecasting models for the timeframe from January 2020 to December 2021. Real procedure numbers were compared with predicted numbers to calculate residual differences, which were considered statistically significant if the real number was outside the 95 % confidence interval (p < 0.05). RESULTS: During the first German lockdown (March/April 2020), the number of outpatient CT/MRI examinations decreased significantly, with a less pronounced decrease of overall CT/MRI numbers. The second German lockdown (January-May 2021) led to lower than predicted outpatient CT numbers, whereas outpatient MRI numbers in part even exceeded predicted numbers and overall CT/MRI numbers stayed within confidence limits. The lockdowns had a more pronounced negative effect on the number of oncological MRI examinations compared to CT examinations. The number of therapeutic interventional oncology procedures showed no significant decrease during both lockdowns. CONCLUSION: Lockdown measures had minor impact on the number of therapeutic interventional oncology procedures, possibly due to a shift from more resource-intensive therapies like surgery towards interventional oncology. The overall numbers of diagnostic imaging decreased during the first lockdown, while the second lockdown had less negative impact. The number of oncological MRI examinations was affected most severely. To avoid adverse outcomes, specific protocols for patient management during future pandemic outbreaks should be implemented and continuously adapted. KEY POINTS: · COVID-19 lockdowns had minor effect on therapeutic interventional oncology procedures.. · Numbers of diagnostic outpatient imaging procedures dropped markedly, especially during the first lockdown.. · The number of oncological MRI examinations showed a significant decrease during both lockdowns.. CITATION FORMAT: · Nebelung H, Radosa CG, Schön F et al. Impact of the COVID-19 pandemic on therapeutic interventional oncology procedures and diagnostic CT/MRI examinations at a German university hospital. Fortschr Röntgenstr 2023; 195: 707 - 712.

Routine Use of Structured Reporting in Whole-body Trauma CT Facilitates Quality Improvement.

PURPOSE: Structured reporting (SR) is increasingly used. So far, there is minimal experience with SR in whole-body computed tomography (WBCT). The aim of this study was to investigate the value of routine use of SR in WBCT in trauma with a focus on reporting time, reporting errors, and referrer satisfaction. MATERIALS AND METHODS: Reporting time and reporting errors of CT reports were prospectively quantified for residents and board-certified radiologists 3 months before and for 6 months after implementation of a structured report in the clinical routine. Referrer satisfaction was prospectively quantified by means of a survey before and after the implementation period of SR using a 5-point Likert scale. Before and after results were compared to determine the effect of structured reporting on WBCT in trauma at our institution. RESULTS: The mean reporting time was lower when using SR (65 ±â€Š52 min. vs. 87 ±â€Š124 min., p = .25). After 4 months, the median reporting time was significantly lower with SR (p = .02). Consequently, the rate of reports that were finished within one hour rose from 55.1 % to 68.3 %. Likewise, reporting errors decreased (12.6 % vs. 8.4 %, p = .48). Residents and board-certified radiologists reported fewer errors when using SR with 16.4 % vs. 12.6 % and 8.8 % vs. 2.7 %, respectively. General referrer satisfaction improved (1.7 ±â€Š0.8 vs. 1.5 ±â€Š1.1, p = .58). Referrers graded improvements for standardization of reports (2.2 ±â€Š1.1 vs. 1.3 ±â€Š1.1, p = .03), consistency of report structure (2.1 ±â€Š1.1 vs. 1.4 ±â€Š1.1, p = .09), and retrievability of relevant pathologies (2.1 ±â€Š1.2 vs. 1.6 ±â€Š1.1, p = .32). CONCLUSION: SR has the potential to facilitate process improvement for WBCT in trauma in the daily routine with a reduction of reporting time and reporting mistakes while increasing referrer satisfaction. KEY POINTS: · SR for WBCT in trauma is feasable in clinical routine.. · Reporting time in WBCT in trauma decreases by SR.. · SR for WBCT in trauma has the potential to decrease reporting mistakes.. · SR for WBCT in trauma might increase referrer satisfaction.. CITATION FORMAT: · Blum SF, Hertzschuch D, Langer E et al. Routine Use of Structured Reporting in Whole-body Trauma CT Facilitates Quality Improvement. Fortschr Röntgenstr 2023; 195: 521 - 528.

Measuring appropriateness of diagnostic imaging: a scoping review.

In radiology, the justification of diagnostic imaging is a key performance indicator. To date, specific recommendations on the measurement of appropriateness in diagnostic imaging are missing. To map the study literature concerning the definition, measures, methods and data used for analyses of appropriateness in research of diagnostic imaging. We conducted a scoping review in Medline, EMBASE, Scopus and the Cochrane Central Register of Controlled Trials. Two independent reviewers undertook screening and data extraction. After screening 6021 records, we included 50 studies. National guidelines (n = 22/50) or American College of Radiology Appropriateness Criteria (n = 23/50) were used to define and rate appropriateness. 22/50 studies did not provide methodological details about the appropriateness assessment. The included studies varied concerning modality, amount of reviewed examinations (88-13,941) and body regions. Computed tomography (27 studies, 27,168 examinations) was the most frequently analyzed modality, followed by magnetic resonance imaging (17 studies, 6559 examinations) and radiography (10 studies, 7095 examinations). Heterogeneous appropriateness rates throughout single studies (0-100%), modalities, and body regions (17-95%) were found. Research on pediatric and outpatient imaging was sparse. Multicentric, methodologically robust and indication-oriented studies would strengthen appropriateness research in diagnostic imaging and help to develop reliable key performance indicators.