Novel deep-learning-based diffusion weighted imaging sequence in 1.5 T breast MRI

PURPOSE

This study aimed to assess the technical feasibility, the impact on image quality, and the acquisition time (TA) of a new deep-learning-based reconstruction algorithm in diffusion weighted imaging (DWI) of breast magnetic resonance imaging (MRI).

METHODS

Retrospective analysis of 55 female patients who underwent breast DWI at 1.5 T. Raw data were reconstructed using a deep-learning (DL) reconstruction algorithm on a subset of the acquired averages, therefore a reduction of TA. Clinically used standard DWI sequence (DWIStd) and the DL-reconstructed images (DWIDL) were compared. Two radiologists rated the image quality of b800 and ADC images, using a Likert-scale from 1 to 5 with 5 being considered perfect image quality. Signal intensities were measured by placing a region of interest (ROI) at the same position in both sequences.

RESULTS

TA was reduced by 40 % in DWIDL, compared to DWIStd, DWIDL improved noise and sharpness while maintaining contrast, the level of artifacts, and diagnostic confidence. There were no differences regarding the signal intensity values of the apparent diffusion coefficient (ADC), (p = 0.955), b50-values (p = 0.070) and b800-values (p = 0.415) comparing standard and DL-imaging. Lesion assessment showed no differences regarding the number of lesions in ADC and DWI (both p = 1.000) and regarding the lesion diameter in DWI (p = 0.961;0.972) and ADC (p = 0.961;0.972).

CONCLUSIONS

The novel deep-learning-based reconstruction algorithm significantly reduces TA in breast DWI, while improving sharpness, reducing noise, and maintaining a comparable level of image quality, artifacts, contrast, and diagnostic confidence. DWIDL does not influence the quantifiable parameters.

Influence of [18F]FDG-PET/CT on Clinical Management Decisions in Breast Cancer Patients-A PET/CT Registry Study

There is a lack of evidence regarding the clinical impact of [¹⁸F]fluorodeoxyglucose positron emission tomography/computed tomography ([¹⁸F]FDG-PET/CT, hereinafter referred to as PET/CT), especially regarding management changes and their link to overall survival. We analyzed 52 PET/CTs in 47 stage I-IV breast cancer patients, selected from a prospective oncological PET/CT registry. Indications for PET/CT were primary staging (n = 15), restaging (n = 17), and suspected recurrence (n = 20). PET/CT-induced management changes were categorized as major or minor. PET/CT-induced management changes in 41 of 52 scans (78.8%; 38 of 47 patients (80.9%)), of which major changes were suggested in 18 of 52 scans (34.6%, 17 of 47 patients, 36.2%). PET/CT downstaged 6 of 15 primary staging patients, excluding distant metastases. Major management changes were documented in 3 of 17 restaging exams. PET/CT ruled out clinically suspected recurrence in 6 of 20 cases and confirmed it in 11 of 20. In three cases, locoregional recurrence had already been diagnosed via biopsy. In 30 of 52 exams, additional diagnostic tests were avoided, of which 13 were invasive. PET/CT-based management changes resulted in a 5-year survival rate of 72.3% for the whole study group, 93.3% for the staging group, 53.8% for the restaging group, and 68.4% for the recurrence group. This study shows that PET/CT significantly impacts clinical management decisions in breast cancer patients in different clinical scenarios, potentially determining the patient's tumor stage as the basis for further therapy more reliably and by avoiding unnecessary diagnostic tests.

Single-centre survival analysis over 10 years after MR-guided radiofrequency ablation of liver metastases from different tumour entities

Background

Radiofrequency ablation (RFA) is a minimal-invasive, local therapy in patients with circumscribed metastatic disease. Although widely used, long time survival analysis of treated liver metastases is still pending while also analysing the patients’ experience of MR-based radiofrequency.

Methods

Monocentric, retrospective analysis of long-time overall and progression free survival (OS; PFS) of 109 patients, treated with MRI-guided hepatic RFA between 1997 and 2010, focusing on colorectal cancer patients (CRC). Complimentary therapies were evaluated and Kaplan Meier-curves were calculated. Patients’ experience of RFA was retrospectively assessed in 28 patients.

Results

1-, 3-, 5-, 10-year OS rates of 109 patients with different tumour entities were 83.4%, 53.4%, 31.0% and 22.9%, median 39.2 months, with decreasing survival rates for larger metastases size. For 72 CRC patients 1-, 3-, 5-, 10-year OS rates of 90.2%, 57.1%, 36.1% and 26.5% were documented (median 39.5 months). Thereof, beneficial outcome was detected for patients with prior surgery of the CRC including chemotherapy (median 53.0 months), and for liver metastases up to 19 mm (28.5% after 145 months). Hepatic PFS was significantly higher in patients with liver lesions up to 29 mm compared to larger ones (p = 0.035). 15/28 patients remembered RFA less incriminatory than other applied therapies.

Conclusions

This is the first single-centre, long-time OS and PFS analysis of MRI-guided hepatic RFA of liver metastases from different tumour entities, serving as basis for further comparison studies. Patients’ experience of MR based RFA should be analysed simultaneously to the performed RFA in the future.

Detection of lung lesions in breath-hold VIBE and free-breathing Spiral VIBE MRI compared to CT

BACKGROUND

Detection of pulmonary nodules in MRI requires fast imaging strategies without respiratory motion impairment, such as single-breath-hold Cartesian VIBE. As patients with pulmonary diseases have limited breath-hold capacities, this study investigates the clinical feasibility of non-Cartesian Spiral VIBE under free-breathing compared to CT as the gold standard.

METHODS

Prospective analysis of 27 oncological patients examined in PET/CT and PET/MR. A novel motion-robust 3D ultrashort-echo-time (UTE) MR sequence was evaluated in comparison with CT and conventional breath-hold MR. CT scans were performed under breath-hold in end-expiratory and end-inspiratory position (CT ex, CT in). MR data was acquired with non-contrast-enhanced breath-hold Cartesian VIBE followed by a free-breathing 3D UTE Spiral VIBE. Impact of respiratory motion on pulmonary evaluation was investigated by two readers in Cartesian VIBE, followed by UTE Spiral VIBE and CT ex and the reference standard of CT in. Diagnostic accuracy was calculated, and visual image quality assessed.

RESULTS

Higher detection rate and sensitivity of pulmonary nodules in free-breathing UTE Spiral VIBE in comparison with breath-hold Cartesian VIBE were found for lesions > 10 mm (UTE Spiral VIBE/VIBE/CT ex): 93%/54%/100%; Lesions 5-10 mm: 67%/25%/ 92%; Lesions < 5 mm: 11%/11%/78%. Lobe-based analysis revealed sensitivities and specificities of 64%/96%/41% and 96%/93%/100% for UTE Spiral VIBE/VIBE/CT ex.

CONCLUSION

Free-breathing UTE Spiral VIBE indicates higher sensitivity for detection of pulmonary nodules than breath-hold Cartesian VIBE and is a promising but time-consuming approach. However, sensitivity and specificity of inspiratory CT remain superior in comparison and should be preferred for detection of pulmonary lesions.

CT texture analysis compared to Positron Emission Tomography (PET) and mutational status in resected melanoma metastases

PURPOSE

To evaluate the potential of CT texture analysis parameters and metabolic characteristics of melanoma metastases in ¹⁸F- FDG PET/CT to predict relevant mutations of tumour cells for targeted therapy in metastatic melanoma patients in correlation with histopathologic specimen.

MATERIAL AND METHODS

66 melanoma patients, examined with contrast-enhanced ¹⁸F-FDG PET/CT before scheduled metastasectomy without any prior systemic therapy, were included in this single-centre retrospective analysis under IRB waiver. The largest, resected metastasis in each patient was assessed with CT texture analysis and semiquantitative ¹⁸F-FDG PET parameters. Correlation between imaging parameters and histopathological mutations (BRAF- and NRAS- genes) were calculated.

RESULTS

Attenuation standard deviation (SD) within target lesion indicated a weak correlation with its SUV_peak (rho -0.292, p 0.017). However, no correlation between CT texture analysis, metabolic ¹⁸F-FDG PET parameters and tumour cell mutation could be established.

CONCLUSION

CT texture parameters cannot replace the diagnostic value of ¹⁸F- FDG PET/CT for metabolic information in melanoma patients. Discrimination between BRAF- and NRAS mutation status was not feasible with CT texture analysis in this exploratory study.

Influence of 18F-FDG PET/CT on clinical management and outcome in patients with advanced melanoma not primarily selected for surgery based on a linked evidence approach

PURPOSE

To evaluate the clinical benefit of positron emission tomography (PET)/computed tomography (CT) in patients with advanced melanoma, primarily not selected for surgery based on management changes and survival data using the linked evidence approach (LEA).

METHODS

A total of 201 ¹⁸F-FDG PET/CT examinations (n = 33, stage III and n = 168, stage IV) in 119 melanoma patients, primarily not scheduled for surgery, were analysed regarding their impact on clinical management. Patients were selected from a prospective oncological PET/CT registry. The three PET/CT indication groups included unclear lesions in conventional imaging (n = 8), routine follow-up after multiple surgeries (n = 115) and therapy response evaluation of systemic therapy (n = 78). PET/CT-induced management changes were categorized either as major (change from follow-up to surgical or systemic treatment or vice versa, change from surgery to systemic therapy or vice versa) or minor (modifications in systemic therapy). The expected benefit of changes was determined via the linked evidence approach (LEA) connecting registry data, outcome data including overall survival and evidence of diagnostic accuracy of PET/CT based on existing literature.

RESULTS

Related to the total study cohort, a change of management after PET/CT was observed in 48% of scans, including 10% minor and 38% major changes. Major changes involved a shift either from follow-up (33/201) or therapy pause (7/201) to systemic therapy, to surgical or other local therapy (26/201) and BSC (2/201). Nine out of 201 cases resulted in treatment pause of systemic therapy. We could confirm the prognostic value of PET/CT-based management by observing a 5-year survival rate more than roughly doubled in patients followed up after tumour exclusion or under local therapy compared with patients under systemic therapy. We could argue for a patient benefit from PET/CT-based management changes using results on accuracy and therapeutic effects from the literature.

CONCLUSION

The use of PET/CT in advanced melanoma patients, primarily not considered for surgery, resulted in frequent changes of management associated with a relevant expected clinical benefit especially in patients classified by PET/CT as tumour-free or eligible for radical surgery.

Practice-based evidence for the clinical benefit of PET/CT-results of the first oncologic PET/CT registry in Germany

PURPOSE

The purpose of this study was to evaluate the impact of PET/CT on clinical management of cancer patients based on a prospective data registry. The study was developed to inform consultations with public health insurances on PET/CT coverage.

METHODS

We evaluated a prospective patient cohort having a clinically indicated PET/CT at a single German University Center from April 2013 to August 2016. The registry collected questionnaire data from requesting physicians on intended patient management before and after PET/CT. A total of 4,504 patients with 5,939 PET/CT examinations were enrolled in the registry, resulting in evaluable data from 3,724 patients receiving 4,754 scans. The impact of PET/CT on patient management was assessed across 22 tumor types, for different indications (diagnosis, staging, suspected recurrence) and different categories of management including treatment (curative or palliative) and non-treatment (watchful waiting, additional imaging, invasive tests).

RESULTS

The most frequent PET/CT indication was tumor staging (59.7%). Melanoma, lung cancer, lymphoma, neuroendocrine tumor and prostate cancer accounted for 70% of cases. Overall, the use of PET/CT resulted in a 37.1% change of clinical management (95% CI, 35.7-38.5), most frequently (30.6%) from an intended non-treatment strategy before PET/CT to active treatment after PET/CT. The frequency of changes ranged from 28.3% for head and neck cancers up to 46.0% for melanomas. The impact of PET/CT was greatest in reducing demands for additional imaging which decreased from 66.1% before PET/CT to 6.1% after PET/CT. Pre-PET/CT planned invasive tests could be avoided in 72.7% of cases. The treatment goal changed after PET/CT in 21.7% of cases, in twice as many cases from curative to palliative therapy than vice versa.

CONCLUSIONS

The data of this large prospective registry confirm that physicians often change their intended management on the basis of PET/CT by initiating treatment and reducing additional imaging as well as invasive tests. This applies to various cancer types and indications.

Impact of 18F-FDG-PET/CT on surgical management in patients with advanced melanoma: an outcome based analysis

PURPOSE

To evaluate the influence of ¹⁸F-FDG-PET/CT on clinical decision making and outcome in advanced melanoma patients planned for radical metastasectomy.

METHODS AND MATERIALS

A cohort of 333 patients with mainly stage III/IV melanoma having a PET/CT for clinical reasons was prospectively enrolled in our oncologic PET/CT registry between 2013 and 2015. Referring physicians completed questionnaires regarding their intended management for each patient before and after PET/CT. Management changes after PET/CT were classified as major and minor changes. A subgroup of 107 patients (stage I, N = 5; stage II, N = 3; stage III, N = 42; stage IV, N = 57) was planned for complete metastasectomy initially, based on conventional imaging. Management changes and outcome were evaluated by linkage with the information obtained from patients' medical records.

RESULTS

In 28 of 107 patients (26%), the surgical treatment plan remained unchanged after PET/CT. In 24 patients (22%), minor changes were performed, such as enlargement or reduction of the surgical field. In 55 patients (51%, 95% CI 42%-61%) major changes of the intended treatment plan occurred; of those, 20 patients (19%) were classified to be tumor-free with PET/CT, 32 patients (30%) were found to have multiple previously unrecognized metastases and had to be treated by systemic therapy, three patients (3%) had to be changed to palliative radiotherapy or isolated extremity perfusion. The 1-year and 2-year overall survival (OS) in patients with complete metastasectomy (N = 52) was 90% and 79%, respectively. Systemically treated patients (N = 32) resulted in 1-year OS of 72% and 2-year OS of 61%. Eleven of 32 patients (34%) with systemic therapy experienced a complete response. Until December 2016, all 20 patients classified as tumor-free by PET/CT were alive.

CONCLUSION

The study confirms the high impact of PET/CT on clinical management in patients with advanced melanoma planned for radical metastasectomy. PET/CT resulted in frequent management changes, preventing futile surgery in half of the patients.

Imaging of Cholangiocarcinoma

Cholangiocarcinoma (CC) is the second most common primary hepatobiliary tumour, and it is increasing in incidence. Imaging characteristics, behaviour, and therapeutic strategies in CC differ significantly, depending on the morphology and location of the tumour. In cross-sectional imaging, CCs can be classified according to the growth pattern (mass-forming, periductal infiltrating, intraductal) and the location (intrahepatic, perihilar, extrahepatic/distal). The prognosis of CC is unfavourable and surgical resection is the only curative treatment option; thus, early diagnosis (also in recurrent disease) and accurate staging including the evaluation of lymph node involvement and vascular infiltration is crucial. However, the diagnostic evaluation of CC is challenging due to the heterogeneous nature of the tumour. Diagnostic modalities used in the imaging of CC include transabdominal ultrasound, endosonography, computed tomography, magnetic resonance imaging with cholangiopancreatography, and hybrid imaging such as positron emission tomography/computed tomography. In this review, the potential of cross-sectional imaging modalities in primary staging, treatment monitoring, and detection of recurrent disease will be discussed.