| 1. |
- Langkilde, Fredrik, 1990, et al.
(författare)
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Manual prostate MRI segmentation by readers with different experience: a study of the learning progress
- 2024
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Ingår i: European Radiology. - 0938-7994 .- 1432-1084.
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To evaluate the learning progress of less experienced readers in prostate MRI segmentation. Materials and methods: One hundred bi-parametric prostate MRI scans were retrospectively selected from the Göteborg Prostate Cancer Screening 2 Trial (single center). Nine readers with varying degrees of segmentation experience were involved: one expert radiologist, two experienced radiology residents, two inexperienced radiology residents, and four novices. The task was to segment the whole prostate gland. The expert’s segmentations were used as reference. For all other readers except three novices, the 100 MRI scans were divided into five rounds (cases 1–10, 11–25, 26–50, 51–76, 76–100). Three novices segmented only 50 cases (three rounds). After each round, a one-on-one feedback session between the expert and the reader was held, with feedback on systematic errors and potential improvements for the next round. Dice similarity coefficient (DSC) > 0.8 was considered accurate. Results: Using DSC > 0.8 as the threshold, the novices had a total of 194 accurate segmentations out of 250 (77.6%). The residents had a total of 397/400 (99.2%) accurate segmentations. In round 1, the novices had 19/40 (47.5%) accurate segmentations, in round 2 41/60 (68.3%), and in round 3 84/100 (84.0%) indicating learning progress. Conclusions: Radiology residents, regardless of prior experience, showed high segmentation accuracy. Novices showed larger interindividual variation and lower segmentation accuracy than radiology residents. To prepare datasets for artificial intelligence (AI) development, employing radiology residents seems safe and provides a good balance between cost-effectiveness and segmentation accuracy. Employing novices should only be considered on an individual basis. Clinical relevance statement: Employing radiology residents for prostate MRI segmentation seems safe and can potentially reduce the workload of expert radiologists. Employing novices should only be considered on an individual basis. Key Points: • Using less experienced readers for prostate MRI segmentation is cost-effective but may reduce quality. • Radiology residents provided high accuracy segmentations while novices showed large inter-reader variability. • To prepare datasets for AI development, employing radiology residents seems safe and might provide a good balance between cost-effectiveness and segmentation accuracy while novices should only be employed on an individual basis. Graphical abstract: [Figure not available: see fulltext.]
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| 2. |
- Nilsson, Markus, et al.
(författare)
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Mapping prostatic microscopic anisotropy using linear and spherical b-tensor encoding : A preliminary study
- 2021
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Ingår i: Magnetic Resonance in Medicine. - : Wiley. - 0740-3194 .- 1522-2594. ; 86:4, s. 2025-2033
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Tensor-valued diffusion encoding provides more specific information than conventional diffusion-weighted imaging (DWI), but has mainly been applied in neuroimaging studies. This study aimed to assess its potential for the imaging of prostate cancer (PCa). Methods: Seventeen patients with histologically proven PCa were enrolled. DWI of the prostate was performed with linear and spherical tensor encoding using a maximal b-value of 1.5 ms/µm2 and a voxel size of 3 × 3 × 4 mm3. The gamma-distribution model was used to estimate the mean diffusivity (MD), the isotropic kurtosis (MKI), and the anisotropic kurtosis (MKA). Regions of interest were placed in MR-defined cancerous tissues, as well as in apparently healthy tissues in the peripheral and transitional zones (PZs and TZs). Results: DWI with linear and spherical encoding yielded different image contrasts at high b-values, which enabled the estimation of MKA and MKI. Compared with healthy tissue (PZs and TZs combined) the cancers displayed a significantly lower MD (P <.05), higher MKI (P < 10−5), and lower MKA (P <.05). Compared with the TZ, tissue in the PZ showed lower MD (P < 10−3) and higher MKA (P < 10−3). No significant differences were found between cancers of different Gleason scores, possibly because of the limited sample size. Conclusion: Tensor-valued diffusion encoding enabled mapping of MKA and MKI in the prostate. The elevated MKI in PCa compared with normal tissues suggests an elevated heterogeneity in the cancers. Increased in-plane resolution could improve tumor delineation in future studies.
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| 3. |
- Ahlberg, Mats Steinholtz, et al.
(författare)
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PCASTt/SPCG-17-A randomised trial of active surveillance in prostate cancer: Rationale and design
- 2019
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Ingår i: BMJ Open. - : BMJ. - 2044-6055. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Overtreatment of localised prostate cancer is substantial despite increased use of active surveillance. No randomised trials help define how to monitor patients or when to initiate treatment with curative intent. Methods and analysis A randomised, multicentre, intervention trial designed to evaluate the safety of an MRI-based active surveillance protocol, with standardised triggers for repeated biopsies and radical treatment. The aim is to reduce overtreatment of prostate cancer. 2000 men will be randomly allocated to either surveillance according to current practice or to standardised triggers at centres in Sweden, Norway, Finland and the UK. Men diagnosed in the past 12 months with prostate cancer, ≤T2a, prostate-specific antigen (PSA) <15 ng/mL, PSA density ≤0.2 ng/mL/cc, any International Society of Urological Pathology (ISUP) grade 1 are eligible. Men with ISUP grade 2 in <30% of cores on systematic biopsy and <10 mm cancer in one core on systematic or targeted biopsy are also eligible. Men diagnosed on systematic biopsy should have an MRI and targeted biopsies against Prostate Imaging and Reporting Data System V.2 3-5 lesions before inclusion. Identical follow-up in the two study arms: biannual PSA testing, yearly clinical examination and MRI every second year. In the experimental arm, standardised triggers based on MRI and PSA density elicit repeated biopsies. MRI and histopathological progression trigger radical treatment. Primary outcome measure is progression-free survival. Secondary outcome measures are cumulative incidence of metastatic disease, treatments with curative intent, pT3-4 at radical prostatectomy, switch to watchful waiting, prostate cancer mortality and quality of life. Inclusion started in October 2016 and in October 2018; 275 patients have been enrolled. Ethics and dissemination Ethical approval was obtained in each participating country. Results for the primary and secondary outcome measures will be submitted for publication in peer-reviewed journals. Trial registration number NCT02914873.
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| 4. |
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| 5. |
- Bratt, Ola, et al.
(författare)
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Satsa på MRT för diagnostik av prostatacancer.
- 2015
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Ingår i: Läkartidningen. - : Läkartidningen Förlag. - 1652-7518 .- 0023-7205. ; 112:Apr 20, s. DFZ3-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 6. |
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| 7. |
- Fisichella, Valeria A, 1974, et al.
(författare)
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Computer-aided detection (CAD) as a second reader using perspective filet view at CT colonography: effect on performance of inexperienced readers.
- 2009
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Ingår i: Clinical Radiology. - : Elsevier BV. - 1365-229X .- 0009-9260. ; 64:10, s. 972-82
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To evaluate whether computer-aided detection (CAD) as a second reader using perspective filet view [three-dimensional (3D) filet] improves the performance of inexperienced readers at computed tomography colonography (CTC) compared with unassisted 3D filet and unassisted two-dimensional (2D) CTC. MATERIAL AND METHODS: Fifty symptomatic patients underwent CTC and same-day colonoscopy with segmental unblinding. Two inexperienced readers read the CTC studies on 3D filet and 2D several weeks apart. Four months later, readers re-read the cases only evaluating CAD marks using 3D filet. Suspicious CAD marks not previously described on 3D filet were recorded. Jackknife free-response receiver operating characteristic (JAFROC-1) analysis was used to compare the observers' performances in detecting lesions with 3D filet, 2D and 3D filet with CAD. RESULTS: One hundred and three lesions > or =3mm were detected at colonoscopy with segmental unblinding. CAD alone had a sensitivity of 73% (75/103) at a mean false-positive rate per patient of 12.8 in supine and 11.4 in prone. For inexperienced readers sensitivities with 3D filet with CAD were 58% (60/103) and 48% (50/103) with an improvement of 14-16 percentage points (p<0.05) compared with 2D and of 10-11 percentage points (p<0.05) compared with 3D filet. For inexperienced readers, the false-positive rate was 25-41% and 71-200% higher with 3D filet with CAD compared with 3D filet and 2D, respectively. JAFROC-1 analysis showed no significant differences in per-lesion overall performance among reading modes (p=0.8). CONCLUSION: CAD applied as a second reader using 3D filet increased both sensitivity and the number of false positives by inexperienced readers compared with 3D filet and 2D, thus not improving overall performance, i.e., the ability to distinguish between lesions and non-lesions.
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| 8. |
- Fisichella, Valeria A, 1974, et al.
(författare)
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Primary three-dimensional analysis with perspective-filet view versus primary two-dimensional analysis: evaluation of lesion detection by inexperienced readers at computed tomographic colonography in symptomatic patients
- 2009
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 50:3, s. 244-55
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Tidskriftsartikel (refereegranskat)abstract
- Background: “Perspective-filet view” is a novel three-dimensional (3D) viewing technique for computed tomography colonography (CTC). Studies with experienced readers have shown a sensitivity for perspective-filet view similar to that of 2D or 3D endoluminal fly-through in detection of colorectal lesions. It is not known whether perspective-filet view, compared to axial images, improves lesion detection by inexperienced readers. Purpose: To compare primary 3D analysis using perspective-filet view (3D Filet) with primary 2D analysis, as used by inexperienced CTC readers. Secondary aims were to compare lesion detection by 3D Filet when used by experienced and inexperienced readers, and to evaluate the effect of combined 3D Filet + 2D analysis. Material and Methods: Fifty symptomatic patients were prospectively enrolled. An experienced reader performed 3D Filet analysis followed by complete 2D analysis (3D Filet + 2D), before colonoscopy with segmental unblinding. Two inexperienced readers (readers 2 and 3), blinded to CTC and colonoscopy findings, retrospectively performed 3D Filet analysis and, after 5 weeks, 2D analysis. True positives ≥6 mm detected by the inexperienced readers with 3D Filet and/or 2D were combined to obtain 3D Filet + 2D. Results: Colonoscopy revealed 116 lesions: 16 lesions ≥10 mm, 19 lesions 6–9 mm, and 81 lesions ≤5 mm. For the experienced reader, sensitivities for lesions ≥6 mm with 3D Filet and 3D Filet + 2D were 77% and 83%, respectively. For the inexperienced readers, sensitivities for lesions ≥6 mm with 3D Filet and 2D were 51% and 57% (reader 2) and 40% and 43% (reader 3), respectively. There was no significant difference between 3D Filet and 2D regarding sensitivity and reading time. For lesions ≥6 mm, 3D Filet + 2D improved the sensitivity of reader 2 to 63% and of reader 3 to 51%. Conclusion: Lesion detection by inexperienced readers using perspective-filet view is comparable to that obtained by 2D. Lesion detection improves by combining 3D Filet + 2D, but not to the level of an experienced reader.
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| 9. |
- Jäderling, Fredrik, et al.
(författare)
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Accuracy in local staging of prostate cancer by adding a three-dimensional T2-weighted sequence with radial reconstructions in magnetic resonance imaging
- 2018
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Ingår i: Acta Radiologica Open. - : Sage Publications. - 2058-4601. ; 7:2
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Tidskriftsartikel (refereegranskat)abstract
- Background: The evidence supporting the use of magnetic resonance imaging (MRI) in prostate cancer detection has been established, but its accuracy in local staging is questioned. Purpose: To investigate the additional value of multi-planar radial reconstructions of a three-dimensional (3D) T2-weighted (T2W) MRI sequence, intercepting the prostate capsule perpendicularly, for improving local staging of prostate cancer. Material and Methods: Preoperative, bi-parametric prostate MRI examinations in 94 patients operated between June 2014 and January 2015 where retrospectively reviewed by two experienced abdominal radiologists. Each patient was presented in two separate sets including diffusion-weighted imaging, without and with the 3D T2W set that included radial reconstructions. Each set was read at least two months apart. Extraprostatic tumor extension (EPE) was assessed according to a 5-point grading scale. Sensitivity and specificity for EPE was calculated and presented as receiver operating characteristics (ROC) with area under the curve (AUC), using histology from whole-mount prostate specimen as gold standard. Inter-rater agreement was calculated for the two different reading modes using Cohen's kappa. Results: The AUC for detection of EPE for Readers 1 and 2 in the two-dimensional (2D) set was 0.70 and 0.68, respectively, and for the 2D+3D set 0.62 and 0.65, respectively. Inter-rater agreement (Reader 1 vs. Reader 2) on EPE using Cohen's kappa for the 2D and 2D+3D set, respectively, was 0.42 and 0.17 (i.e. moderate and poor agreement, respectively). Conclusion: The addition of 3D T2W MRI with radial reconstructions did not improve local staging in prostate cancer.
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| 10. |
- Jäderling, Fredrik
(författare)
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Preoperative local staging of prostate cancer : aspects on predictive models, magnetic resonance imaging and interdisciplinary teamwork
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In prostate cancer surgery the two issues at stake are the removal of the tumour on one hand and functional outcome i.e. urinary continence and sexual function on the other. A nerve preserving procedure will optimise the functional outcome but introduces the risk of positive surgical margins by accidentally leaving small tumour remnants behind, thus risking a poor oncological outcome. Preoperative knowledge of tumour aggressiveness, location and whether local growth is confined to the prostate is of outmost importance for an optimal outcome. Currently available tools that provide the surgeon with preoperative information on which to base the treatment decision and surgical technique are far from perfect. The overall aim of this thesis was to explore ways to improve preoperative local staging of prostate cancer, including the development of a prediction tool and the use of magnetic resonance imaging (MRI) in the decision of surgical method. In Paper 1 we found that of men who underwent surgery with preoperative characteristics implicating very low risk disease, one third had adverse pathology outcome i.e. non‐organ confined tumours and/or more aggressive tumour features at pathology. Sixteen percent had positive surgical margins and only 40% were urinary continent and sexually potent 12 months after surgery. The findings describe both the shortcomings of the preoperative work‐up and the risks linked to surgery. It also gives support to active surveillance, where active treatment is deferred, as an option for men with very low risk, albeit after careful risk stratification where MRI should play an important role to rule out maleficent tumours. Patients with tumour that on clinical examination are classified as organ‐confined will in approximately one third of the cases subsequently be reclassified at pathology as non‐organ confined. In Paper 2 the development of a prediction tool from preoperative variables, predicting non‐organ confined disease, is described. The accuracy of the final model was only moderate and when validated on an external group showed even lower performance. We found that the probable cause of the low performance was due to variability between pathologists in judgement of our primary outcome measure, tumour stage. This underlines the need for validation before the use of an externally derived prediction model. Paper 3 investigated the additional value of a three‐dimensional (3D) T2‐weighted sequence with radial reconstructions, in local staging of patients receiving a preoperative prostate MRI. A radial reconstruction overcomes the partial volume effect encountered at the curved portions of the prostate seen with conventional imaging methods. The outcome however showed no benefits of adding the 3D sequence but rather introduced an uncertainty when comparing assessments from two radiologists, with an inter‐rater correlation of 0.17 (poor agreement) compared to traditional sequences of 0.42 (moderate agreement). In Paper 4 we compared outcome measures from pathology regarding positive surgical margins between (A) men who had performed a preoperative MRI discussed at an interdisciplinary consensus conference between surgeons and a radiologist and (B) men who were operated on without a preoperative MRI. The group receiving MRI and a conference showed a significant reduction in positive surgical margins but at the cost of less nerve sparing procedures, compared to those men not receiving a preoperative MRI. The findings of this thesis highlight the difficulties encountered at prediction of local tumour stage in prostate cancer at all stages of the preoperative investigation. This implicates the need for improvements, with tuning and standardisation of the different preoperative investigational modalities for better oncological and functional outcome in men undergoing treatment with curative intent. This should be carried out in a multi‐disciplinary setting, to optimize and increase the knowledge of all specialists involved in the care of prostate cancer patients.
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