"Image quality evaluation of the Precise image CT deep learning reconstruction algorithm compared to Filtered Back-projection and iDose4: a phantom study at different dose levels".

PURPOSE: To characterize the performance of the Precise Image (PI) deep learning reconstruction (DLR) algorithm for abdominal Computed Tomography (CT) imaging. METHODS: CT images of the Catphan-600 phantom (equipped with an external annulus) were acquired using an abdominal protocol at four dose levels and reconstructed using FBP, iDose4 (levels 2,5) and PI ('Soft Tissue' definition, levels 'Sharper','Sharp','Standard','Smooth','Smoother'). Image noise, image non-uniformity, noise power spectrum (NPS), target transfer function (TTF), detectability index (d'), CT numbers accuracy and image histograms were analyzed. RESULTS: The behavior of the PI algorithm depended strongly on the selected level of reconstruction. The phantom analysis suggested that the PI image noise decreased linearly by varying the level of reconstruction from Sharper to Smoother, expressing a noise reduction up to 80% with respect to FBP. Additionally, the non-uniformity decreased, the histograms became narrower, and d' values increased as PI reconstruction levels changed from Sharper to Smoother. PI had no significant impact on the average CT number of different contrast objects. The conventional FBP NPS was deeply altered only by Smooth and Smoother levels of reconstruction. Furthermore, spatial resolution was found to be dose- and contrast-dependent, but in each analyzed condition it was greater than or comparable to FBP and iDose4 TTFs. CONCLUSIONS: The PI algorithm can reduce image noise with respect to FBP and iDose4; spatial resolution, CT numbers and image uniformity are generally preserved by the algorithm but changes in NPS for the Smooth and Smoother levels need to be considered in protocols implementation.

Automated Prediction of the Response to Neoadjuvant Chemoradiotherapy in Patients Affected by Rectal Cancer.

BACKGROUND: Rectal cancer is a malignant neoplasm of the large intestine resulting from the uncontrolled proliferation of the rectal tract. Predicting the pathologic response of neoadjuvant chemoradiotherapy at an MRI primary staging scan in patients affected by locally advanced rectal cancer (LARC) could lead to significant improvement in the survival and quality of life of the patients. In this study, the possibility of automatizing this estimation from a primary staging MRI scan, using a fully automated artificial intelligence-based model for the segmentation and consequent characterization of the tumor areas using radiomic features was evaluated. The TRG score was used to evaluate the clinical outcome. METHODS: Forty-three patients under treatment in the IRCCS Sant'Orsola-Malpighi Polyclinic were retrospectively selected for the study; a U-Net model was trained for the automated segmentation of the tumor areas; the radiomic features were collected and used to predict the tumor regression grade (TRG) score. RESULTS: The segmentation of tumor areas outperformed the state-of-the-art results in terms of the Dice score coefficient or was comparable to them but with the advantage of considering mucinous cases. Analysis of the radiomic features extracted from the lesion areas allowed us to predict the TRG score, with the results agreeing with the state-of-the-art results. CONCLUSIONS: The results obtained regarding TRG prediction using the proposed fully automated pipeline prove its possible usage as a viable decision support system for radiologists in clinical practice.

Statement of the Italian Association of Medical Physics (AIFM) task group on radiation dose monitoring systems.

The evaluation of radiation burden in vivo is crucial in modern radiology as stated also in the European Directive 2013/59/Euratom-Basic Safety Standard. Although radiation dose monitoring can impact the justification and optimization of radiological procedure, as well as effective patient communication, standardization of radiation monitoring software is far to be achieved. Toward this goal, the Italian Association of Medical Physics (AIFM) published a report describing the state of the art and standard guidelines in radiation dose monitoring system quality assurance. This article reports the AIFM statement about radiation dose monitoring systems (RDMSs) summarizing the different critical points of the systems related to Medical Physicist Expert (MPE) activities before, during, and after their clinical implementation. In particular, the article describes the general aspects of radiation dose data management, radiation dose monitoring systems, data integrity, and data responsibilities. Furthermore, the acceptance tests that need to be implemented and the most relevant dosimetric data for each radiological modalities are reported under the MPE responsibility.

A single phantom, a single statistical method for low-contrast detectability assessment.

PURPOSE: The assessment of low-contrast-details is a part of the quality control (QC) program in digital radiology. It generally consists of evaluating the threshold contrast (Cth) detectability details for different-sized inserts, appropriately located in dedicated QC test tools. This work aims to propose a simplified method, based on a statistical model approach for threshold contrast estimation, suitable for different modalities in digital radiology. METHODS: A home-madelow-contrast phantom, made of a central aluminium insert with a step-wedge, was assembled and tested. The reliability and robustness of the method were investigated for Mammography, Digital Radiography, Fluoroscopy and Angiography. Imageswere analysed using our dedicated software developed on Matlab®. TheCth is expressed in the same unit (mmAl) for all studied modalities. RESULTS: This method allows the collection of Cthinformation from different modalities and equipment by different vendors, and it could be used to define typical values. Results are summarized in detail. For 0.5 diameter detail, Cthresults are in the range of: 0.018-0.023 mmAl for 2D mammography and 0.26-0.34 mmAl DR images. For angiographic images, for 2.5 mm diameter detail, the Cths median values are 0.55, 0.4, 0.06, 0.12 mmAl for low dose fluoroscopy, coronary fluorography, cerebral and abdominal DSA, respectively. CONCLUSIONS: The statistical method proposed in this study gives a simple approach for Low-Contrast-Details assessment, and the typical values proposed can be implemented in a QA program for digital radiology modalities.

Computed Tomography-Colonography With Intravenous Contrast Medium and Urographic Phase for the Evaluation of Pelvic Deep Infiltrating Endometriosis of Intestinal and Urinary Tract.

OBJECTIVES: The aim of this study was to evaluate the diagnostic accuracy of a specific protocol of computed tomography-colonography with intravenous contrast medium and urographic phase, which combined simultaneously the study of the intestinal and urinary tract, in the preoperative evaluation of women with deep infiltrating endometriosis (DIE) of anterior and posterior pelvic compartments. METHODS: We retrospectively analyzed 73 women who underwent 74 computed tomography-colonography with intravenous contrast medium and urographic phase examinations for strong clinical suspicion of DIE. All the women had surgical confirmation. RESULTS: Computed tomography-colonography with intravenous contrast medium and urographic phase in detecting DIE rectosigmoid involvement had a sensitivity of 82.3% and a specificity of 66.7%, while in detecting DIE urinary tract involvement had a sensitivity of 45.9% and a specificity of 78.4%. CONCLUSIONS: Computed tomography-colonography with intravenous contrast medium and urographic phase is a useful technique for the preoperative planning of selected women with DIE, in particular, for the detection of sigmoid colon and bladder lesions especially when performed with a dose reduction protocol.

Practical recommendations for the application of DE 59/2013.

The changes introduced with Council Directive 2013/59/Euratom will require European Member States adapt their regulations, procedures and equipment to the new high standards of radiation safety. These new requirements will have an impact, in particular, on the radiology community (including medical physics experts) and on industry. Relevant changes include new definitions, a new dose limit for the eye lens, non-medical imaging exposures, procedures in asymptomatic individuals, the use and regular review of diagnostic reference levels (including interventional procedures), dosimetric information in imaging systems and its transfer to the examination report, new requirements on responsibilities, the registry and analysis of accidental or unintended exposure and population dose evaluation (based on age and gender distribution). Furthermore, the Directive emphasises the need for justification of medical exposure (including asymptomatic individuals), introduces requirements concerning patient information and strengthens those for recording and reporting doses from radiological procedures, the use of diagnostic reference levels, the availability of dose-indicating devices and the improved role and support of the medical physics experts in imaging.

Split-Bolus Multidetector-Row Computed Tomography Technique for Characterization of Focal Liver Lesions in Oncologic Patients.

BACKGROUND: In oncologic patients, the liver is the most common target for metastases. An accurate detection and characterization of focal liver lesions in patients with known primary extrahepatic malignancy are essential to define management and prognosis. OBJECTIVES: To assess the diagnostic accuracy of the split-bolus multidetector-row computed tomography (MDCT) protocol in the characterization of focal liver lesions in oncologic patients. PATIENTS AND METHODS: We retrospectively analyzed the follow-up split-bolus 64-detector row CT protocol in 36 oncologic patients to characterize focal liver lesions. The split-bolus MDCT protocol by intravenous injection of two boluses of contrast medium combines the hepatic arterial phase (HAP) and hepatic enhancement during the portal venous phase (PVP) in a single-pass. RESULTS: The split-bolus MDCT protocol detected 208 lesions and characterized 186 (89.4%) of them: typical hemangiomas (n = 9), atypical hemangiomas (n = 3), cysts (n = 78), hypovascular (n = 93) and hypervascular (n = 3) metastases. Twenty two (10.6%) hypodense lesions were categorized as indeterminate (≤5 mm). The mean radiation dose was 24.5±6.5 millisieverts (mSv). CONCLUSION: The designed split-bolus MDCT technique can be proposed alternatively to triphasic MDCT and in a single-pass to PVP in the initial staging and in the follow-up respectively in oncologic patients.

Split-Bolus Single-Pass Multidetector-Row CT Protocol for Diagnosis of Acute Pulmonary Embolism.

BACKGROUND: Currently computed tomography pulmonary angiography (CTPA) has become a widely accepted clinical tool in the diagnosis of acute pulmonary embolism (PE). OBJECTIVES: To report split-bolus single-pass 64-multidetector-row CT (MDCT) protocol for diagnosis of PE. PATIENTS AND METHODS: MDCT split-bolus results in 40 patients suspicious of PE were analyzed in terms of image quality of target pulmonary vessels (TPVs) and occurrence and severity of flow-related artifact, flow-related artifact, false filling defect of the pulmonary veins and beam hardening streak artifacts. Dose radiation to patients was calculated. RESULTS: MDCT split-bolus protocol allowed diagnostic images of high quality in all cases. Diagnosis of PE was obtained in 22 of 40 patients. Mean attenuation for target vessels was higher than 250 HU all cases: 361 ± 98 HU in pulmonary artery trunk (PAT); 339 ± 93 HU in right pulmonary artery (RPA); 334 ± 100 HU in left pulmonary artery (LPA). Adequate enhancement was obtained in the right atrium (RA):292 ± 83 HU; right pulmonary vein (RPV): 302 ± 91 HU, and left pulmonary vein (LPV): 291 ± 83 HU. The flow related artifacts and the beam hardening streak artifacts have been detected respectively in 4 and 25 patients. No false filling defect of the pulmonary veins was revealed. CONCLUSION: MDCT split-bolus technique by simultaneous opacification of pulmonary arteries and veins represents an accurate technique for diagnosis of acute PE, removes the false filling defects of the pulmonary veins, and reduces flow related artifacts.

Results of an Italian survey on teleradiology.

OBJECTIVES: The aim of this study is to present the results of the Italian survey on teleradiology (TR). METHODS: Two radiologists created an online electronic survey using the Survey Monkey web-based tool. The questionnaire was then improved by suggestions from a multidisciplinary group of experts. In its final form, the survey consisted of 19 multiple-choice questions. Space was left below each question for participants to add their personal comments. Members of Italian Society of Medical Radiology (SIRM) were given 2 weeks to perform the survey. RESULTS: A total of 1599 radiologists, corresponding to 17 % of all SIRM radiologists, participated into the online survey. As a result, 62 % of participants have a positive opinion on teleradiology, while 80 % including 18 % with a negative opinion believe that teleradiology will have a future. 55 % of responders (n = 874) use teleradiology in their clinical practice. The majority of users adopt intra-mural teleradiology for coverage of emergencies (47 %), of night and weekend shifts (37 %) or to even out distribution workload (33 %). Most responders still show concern on the use of teleradiology. In particular, they think that teleradiology is too impersonal (40 %), and that it is responsible for insufficient communication with the referring clinician (39 %). CONCLUSIONS: The majority of Italian radiologists are favorable to teleradiology. However, they have concerns that teleradiology may further reduce communication with the referring clinician ad patient.

FDG PET and Split-Bolus Multi-Detector Row CT Fusion Imaging in Oncologic Patients: Preliminary Results.

PURPOSE: To assess the incremental value of split-bolus multidetector computed tomography (CT) combined with fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) for follow-up of oncologic patients. MATERIALS AND METHODS: The institutional ethics committee approved the use of this protocol. Thirty-eight oncologic patients who underwent FDG PET/unenhanced multidetector CT and split-bolus multidetector CT for restaging were investigated retrospectively. The split-bolus CT protocol included imaging during the hepatic arterial and portal venous phases in one scan. Software was used for fusion of the independently acquired FDG PET and split-bolus CT data, and fused datasets were compared with FDG PET/unenhanced CT data. The standard of reference for diagnosis of lesions in all patients was a combination of histologic results (if available), clinical results (medical history, physical examination, and laboratory test results), and the results of follow-up imaging (conventional CT, magnetic resonance imaging, and/or ultrasonography) for at least 6 months. Descriptive statistics were used. RESULTS: Fifty-nine true-positive lesions were identified with fused FDG PET/split-bolus CT; 41 were concordant and detected with both split-bolus CT and PET/unenhanced CT, 16 with split-bolus CT only, and two with PET/unenhanced CT. Two different false-positive lesions were identified with PET/unenhanced CT and PET/split-bolus CT. Furthermore, in 20 of 38 (53%) patients, FDG PET/split-bolus CT allowed detection of important additional findings (n = 40) not detected at FDG PET/unenhanced CT. Both the tumor-related findings (n = 13, 32.5%) and the non-tumor-related findings (n = 27, 67.5%) were important to the clinical treatment of these patients. CONCLUSION: Fused FDG PET/split-bolus multidetector CT provides additional information compared with FDG PET/unenhanced multidetector CT in oncologic patients.

Split-bolus versus triphasic multidetector-row computed tomography technique in the diagnosis of hepatic focal nodular hyperplasia: a case report.

INTRODUCTION: Computed tomography and magnetic resonance imaging are able to demonstrate and to diagnose hepatic focal nodular hyperplasia when a typical pattern of a well-circumscribed lesion with a central scar is present.Our aim is to propose the split-bolus multidetector-row computed tomography technique as an alternative to the conventional triphasic technique in the detection and characterization of focal nodular hyperplasia to reduce the radiation dose to the patient.To the best of our knowledge, this is the first report regarding the application of the split-bolus computed tomography technique in the evaluation of hepatic focal nodular hyperplasia. CASE PRESENTATION: We describe a case of focal nodular hyperplasia of the liver in a 53-year-old Caucasian woman (weight 75Kg) with a colorectal adenocarcinoma histologically confirmed. An innovative split-bolus multidetector-row computed tomography technique was used that, by splitting intravenous contrast material in two boli, combined two phases (hepatic arterial phase and portal venous phase) in a single pass; a delayed (5 minutes) phase was obtained to compare the findings with that of triphasic multidetector-row computed tomography. CONCLUSIONS: Split-bolus multidetector-row computed tomography was able to show the same appearance of the lesion as the triphasic multidetector-row computed tomography technique.This is the first case demonstrating the effectiveness of the split-bolus multidetector-row computed tomography technique in the detection and characterization of focal nodular hyperplasia with a significant reduction in radiation dose to the patient with respect to triphasic multidetector-row computed tomography technique.

Detection and characterization of focal liver lesions by split-bolus multidetector-row CT: diagnostic accuracy and radiation dose in oncologic patients.

AIM: To assess the diagnostic accuracy and radiation dose of split-bolus multidetector-row computed tomography (MDCT) protocol in the detection and characterization of focal liver lesions in oncologic patients. PATIENTS AND METHODS: We retrospectively analyzed triphasic CT at initial diagnosis and follow-up split-bolus 64-detector row CT protocol in 48 oncologic patients with focal liver lesions. Split-bolus MDCT protocol by i.v. injection of two boli of contrast medium combines hepatic arterial phase (HAP) and hepatic enhancement during portal venous phase (PVP) in a single pass. First bolus: 75-90 mL at 2.0 mL/sec to obtain adequate hepatic enhancement during the PVP; second bolus: 60 mL/sec at 3.5 mL/sec to ensure HAP. Each bolus is followed by 20 mL of saline solution at the same flow rate. Sensitivity, specificity, positive predictive value and negative predictive value of split-bolus MDCT protocol were calculated for detection and characterization of liver lesions. The effective radiation dose (ED) was calculated using dose-length product (DLP) values in mSv determined using a conversion factor. RESULTS: compared to triphasic-MDCT, split-bolus MDCT protocol confirmed all the 210 lesions identified and characterized by triphasic-MDCT technique, unchanged during the follow-up. The mean ED was 27.8 ± 6 mSv for chest-abdomen-pelvis biphasic split-bolus MDCT and 45.7 ± 13.6 mSv for triphasic-MDCT. CONCLUSION: The diagnostic efficacy of split-bolus protocol is comparable to that of triphasic protocol at MDCT with a reduction in radiation dose of approximately 35-40%.

Detection of small (≤ 2 cm) pancreatic adenocarcinoma and surrounding parenchyma: correlations between enhancement patterns at triphasic MDCT and histologic features.

BACKGROUND: The aim is to assess the time-density curves (TDCs) and correlate the histologic results for small (≤ 2 cm) PDA and surrounding parenchyma at triphasic Multidetector-row CT (MDCT). METHODS: Triphasic MDCT scans of 38 consecutive patients who underwent surgery for a small PDA were retrospectively reviewed. The TDCs were analyzed and compared with histologic examination of the PDA and pancreas upstream/downstream in all cases. Three enhancement patterns were identified: 1) enhancement peak during pancreatic parenchymal phase (PPP) followed by a rapid decline on portal venous phase (PVP) and delayed phase (DP) at 5 minutes (type 1 pattern: normal pancreas); 2) maximum enhancement in PVP that gradually decreases in DP (type 2 pattern: mild chronic pancreatitis or PDA with mild fibrous stroma); 3) progressive enhancement with maximum peak in DP (type 3 pattern: severe chronic pancreatitis or PDA with severe fibrous stroma). A p value less than 0.05 was considered statistically significant. Sensitivity was calculated for PDA detection and an attenuation difference with the surrounding tissue of at least 10 HU was considered. RESULTS: PDA showed type 2 pattern in 5/38 cases (13.2%) and type 3 pattern in 33/38 cases (86,8%). Pancreas upstream to the tumor had type 2 pattern in 20/38 cases (52,6%) and type 3 pattern in 18/38 cases (47,4%). Pancreas downstream to the tumor had type 1 pattern in 19/25 cases (76%) and type 2 pattern in 6/25 cases (24%). Attenuation difference between tumor and parenchyma upstream was higher of 10 UH on PPP in 31/38 patients (sensitivity = 81.6%), on PVP in 29/38 (sensitivity = 76.3%) and on DP in 17/38 (sensitivity = 44.7%). Attenuation difference between tumor and parenchyma downstream was higher of 10 UH on PPP in 25/25 patients (sensitivity = 100%), on PVP in 22/25 (sensitivity = 88%) and on DP in 20/25 (sensitivity = 80%). Small PDAs were isodense to the pancreas upstream to the tumor, and therefore unrecognizable, in 8 cases (8/38; 21%) at qualitative analysis and in 4 cases (4/38; 10,5%) at quantitative analysis. CONCLUSIONS: The quantitative analysis increases the sensitivity for detection of small PDA at triphasic MDCT.

[Small renal cell carcinoma (≤ 4 cm): enhancement patterns on triphasic spiral CT]. / Carcinoma renale di piccole dimensioni (≤4 cm): pattern di enhancement con TC spirale multistrato trifasica.

The aim of this study was to define enhancement patterns of small renal cell carcinoma (RCC) (≤4 cm) by triphasic spiral CT. In 24 patients with RCC, hypervascularity and hypovascularity were identified in 12 and 12 RO, respectively, in the cortico-medullary phase (CMP). Hypervascular RCC showed increased density in the CMP (170,7±46,3 UH) and a gradual wash-out in the nephrographic phase (NP) (152,5±41 UH) and pielographic phase (PF) (99,2±38 UH). Hypovascular RCC showed increased density in the CMP (52,9±24,7 UH) and a gradual wash-out in NP (64,5±16,9 UH) and PP phases (55,0±17,3 UH).

Application of QC_DR software for acceptance testing and routine quality control of direct digital radiography systems: initial experiences using the Italian Association of Physicist in Medicine quality control protocol.

Ideally, medical x-ray imaging systems should be designed to deliver maximum image quality at an acceptable radiation risk to the patient. Quality assurance procedures are employed to ensure that these standards are maintained. A quality control protocol for direct digital radiography (DDR) systems is described and discussed. Software to automatically process and analyze the required images was developed. In this paper, the initial results obtained on equipment of different DDR manufacturers were reported. The protocol was developed to highlight even small discrepancies in standard operating performance.

Monte Carlo modelling of a voxel head phantom for in vivo measurement of bone-seeker nuclides.

Whole-body counters (WBCs) are used for the assessment of the internal contamination of actinides in the human body. WBCs require adequate calibration procedures that rely on the use of suitable calibration phantoms. A previous study carried out at the ENEA-Radiation Protection Institute was aimed at designing a head calibration phantom in which a heterogeneous distribution of 241Am point sources could satisfactorily approximate an assumed homogeneous contamination throughout the head bones. Suitable correction factors for the WBC detection efficiencies were evaluated with Monte Carlo. The present paper summarises the main aspects and implications of an advanced modelling technique based on a VOXEL approach. The methodology could be extended to other bone-seeker radionuclides.