Software-based Fusion Research Articles

A prospective study on inter-operator variability in semi-robotic software-based MRI/TRUS-fusion targeted prostate biopsies

PurposeMagnetic resonance imaging (MRI)/ultrasound-fusion prostate biopsy (FB) comprises multiple steps each of which can cause alterations in targeted biopsy (TB) accuracy leading to false-negative results. The aim was to assess the inter-operator variability of software-based fusion TB by targeting the same MRI-lesions by different urologists.MethodsIn this prospective study, 142 patients eligible for analysis underwent software-based FB. TB of all lesions (n = 172) were carried out by two different urologists per patient (n = 31 urologists). We analyzed the number of mismatches [overall prostate cancer (PCa), clinically significant PCa (csPCa) and non-significant PCa (nsPCa)] between both performed TB per patient. In addition we evaluated factors contributing to inter-operator variability by uni- and multivariable analyses.ResultsIn 11.6% of all MRI-lesions (10.6% of all patients) there was a mismatch between TB1 and TB2 in terms of overall prostate cancer (PCa detection. Regarding csPCa, patient-based mismatch occurred in 14.8% (n = 21). Overall PCa and csPCa detection rate of TB1 and TB2 did not differ significantly on a per-patient and per-lesion level.Analyses revealed a smaller lesion size as predictive for mismatches (OR 9.19, 95% CI 2.02–41.83, p < 0.001).ConclusionReproducibility and precision of targeting particularly small lesions is still limited although using software-based FB. Further improvements in image-fusion, segmentation, needle-guidance, and automatization are necessary.

MRI/US fusion prostate biopsy in men on active surveillance: Our experience.

The upgrading or staging in men with prostate cancer (PCA) undergoing active surveillance (AS), defined as Gleason score (GS) ≥ 3+4 or more than 2 area with cancer, was investigated in our experience using the software-based fusion biopsy (FB). We selected from our database, composed of 620 biopsies, only men on AS according to criteria of John Hopkins Protocol (T1c, < 3 positive cores, GS = 3+3 = 6). Monitoring consisted of PSA measurement every 3 months, a clinical examination every 6 months, confirmatory FB within 6 months and then annual FB in all men. The suspicious MRI lesions were scored according to the Prostate Imaging Reporting and Data System (PI-RADS) classification version 2. FB were performed with a transrectal elastic free-hand fusion platform. The overall and clinically significant cancer detection rate was reported. Secondary, the diagnostic role of systematic biopsies was evaluated. We selected 56 patients on AS with mean age 67.4 years, mean PSA 6.7 ng/ml and at least one follow-up MRI-US fusion biopsy (10 had 2 or 3 follow-up biopsies). Lesions detected by MRI were: PIRADS-2 in 5, PIRADS-3 in 28, PIRADS-4 in 18 pts and PIRADS-5 in 5 patients. In each MRI lesion, FB with 2.1 ± 1.1 cores were taken with a mean total cores of 13 ± 2.4 including the systematic cores. The overall cancer detection rate was 71% (40/56): 62% (25/40) in target core and 28% (15/40) in systematic core. The overall significant cancer detection rate was 46% (26/56): 69% (18/26) in target vs 31% (8/26) in random cores. The incidence of clinical significant cancer was 46% in men starting active surveillance, but it was more than doubled using MRI/US Target Biopsy 69% (18/26) rather than random cores (31%, 8/26). However, 1/3 of disease upgrades would have been missed if only the targeted biopsies were performed. Based on our experience, MRI/US fusion target biopsy must be associated to systematic biopsies to improve detection of significant cancer, reducing the risks of misclassification.

Study protocol for a single-centre non-inferior randomised controlled trial on a novel three-dimensional matrix positioning-based cognitive fusion-targeted biopsy and software-based fusion-targeted biopsy for the detection rate of clinically significant prostate cancer in men without a prior biopsy

IntroductionThe classical pathway for diagnosing prostate cancer is systematic 12-core biopsy under the guidance of transrectal ultrasound, which tends to underdiagnose the clinically significant tumour and overdiagnose the insignificant disease....

The utility of in-bore multiparametric magnetic resonance-guided biopsy in men with negative multiparametric magnetic resonance-ultrasound software-based fusion targeted biopsy

ObjectivesTo evaluate the utility of in-bore multiparametric magnetic resonance-guided biopsy of the prostate (IB) in patients with visible lesion/s and previous negative software-based multiparametric magnetic resonance imaging/ultrasonography fusion-targeted biopsy of the prostate (FTB). Patients and methodsWe retrospectively analysed prospectively maintained database including consecutive men undergoing IB from March 2013 to October 2017 in 2 European centres expert in this procedure. We selected men with the following criteria: No previous treatment for prostate cancer (CaP), multiparametric magnetic resonance imaging (mpMRI) lesion(s) PIRADS score ≥ 3, FTB showing no clinically significant cancer (csCaP), and subsequent IB. Patient's characteristics, mpMRI findings, biopsy technique, and histopathological results were extracted. The primary outcome was to determine the detection rate of csCaP, defined as any Gleason pattern ≥ 4. A multivariable analysis was performed to identify predictors of positive findings at IB. ResultsFifty-three men were included. Median age was 68 years (interquartile range [IQR] 64–68), median Prostate-Specific Antigen (PSA) was 7.6 ng/ml (IQR 5.2–10.9), and median prostate volume was 59 ml (IQR 44–84). Fifty-six lesions with PIRADS score 3 in 9 cases (16%), 4 in 30 cases (54%), and 5 in 17 cases (30%) were detected. FTB was performed in all cases using a transrectal approach with 3 different platforms (Toshiba, Koelis, and Artemis). Median time between FTB and IB was 3 months (IQR 1–7). A median of 2 cores per lesion were collected with IB (IQR 2–3). No cancer, clinically insignificant and clinically significant cancer were found in 33 (59%), 9 (16%), and 14 (25%) targeted lesions, respectively. Median maximum cancer core length and maximum positive percentage were 9 mm (3–13) and 55% (21%–80%). The only predictor of csCaP on IB was prostate volume (P = 0.026) with an ideal cut-off at 70 ml. ConclusionOne in 4 patients with previous negative FTB, IB was able to detect csCaP. According to this study, IB would be of particularly useful in patients with large glands.

PT422 - Centre and operator impact on MRI-targeting performance for grade group prediction during software-based fusion biopsies

PT422 - Centre and operator impact on MRI-targeting performance for grade group prediction during software-based fusion biopsies

Intercenter reproducibility of software-based fusion biopsies for grade group prediction when targeting suspicious MRI lesions

PurposeTo assess the intercenter reproducibility of software-based fusion targeted biopsy (TB) for grade-group assessment and pretherapeutic evaluation of highly suspicious MRI lesions. Patients and methodsIn this study, were included 380 consecutive patients who underwent radical prostatectomy (RP) after prostate cancer diagnosis and a prebiopsy MRI showing Prostate Imaging-Reporting and Data System (PIRADS) score 4 or 5 lesions. All patients underwent systematic biopsies (SB) combined with software-based fusion TB in the 2 centers. Biopsies were only performed by expert urologists or radiologists in a contemporary time frame. The primary endpoint was the center difference of concordance/upgrading rates between biopsy and RP specimens. ResultsPathological features on biopsy and RP specimens were significantly different among centers with more unfavourable disease in center 1. The rate of TB upgrading was 33.6% in center 1 vs. 35.4% (P = 0.860) in center 2. Grading concordance was also comparable among centers (50.0% vs. 47.1%) as well as the SB upgrading rate. Regression analysis did not find any baseline characteristics (Age, prostate-specific antigen, MRI lesions, center) predictive for TB upgrading. These findings were achieved by using fewer TB per lesion in center 1 (2.3 vs. 5.0, P < 0.001), at the expense of more SB cores (14.4 vs. 8.5, P < 0.001). The influence of MRI characteristics (lesion size and number, PIRADS score) on upgrading rates was consistent among centers. ConclusionsSoftware-based fusion TB technique leads to comparable outcomes in terms of grade group prediction accuracy in PIRADS 4 to 5 lesions, insignificant between centers, in spite of different non imaging-based aggressiveness features.

Impact of MRI and Targeted Biopsies on Eligibility and Disease Reclassification in MRI-positive Candidates for Active Surveillance on Systematic Biopsies

OBJECTIVETo assess the impact of concomitant targeted biopsies (TB) for predicting final disease reclassification in MRI-positive low-risk prostate cancer patients eligible for active surveillance (AS) on systematic biopsies (SB). MATERIALS AND METHODSFrom a prospective database, we included all prebiopsy MRI-positive men fulfilling AS criteria at diagnosis (Toronto [n = 114], UCSF [n = 82], or PRIAS [n = 60] criteria) on SB. All patients underwent a combination of SB and software-based fusion TB, and an immediate radical prostatectomy. The primary endpoints were the pathologic upgrading and upstaging rates. RESULTSBiopsy grade group was upgraded to grade group (GG) 2 and to GG≥3 on TB in 65.9%-76.7% and in 12.2-16.7%, respectively. The rate of GG ≥3 in radical prostatectomy specimens varied from 31.6% to 43.3% with no relation between strictest criteria and lower upgrading rates. The proportion of not organ-confined disease (35%-39%) was comparable among the AS cohorts. Negative TB was strongly associated with the absence of final GG ≥3. Tumor grade on TB was significantly correlated with the risk of final GG ≥3 in both Toronto and UCSF cohorts, not in the PRIAS cohort. In the PRIAS cohort, the only independent predictive factor for GG ≥3 disease was the maximal tumor length in any core (P = .034). CONCLUSIONIn MRI-positive patients, the risk of disease reclassification was comparable whatever the SB-based AS criteria used. TB were predictive of final upgrading, with a varied impact according to the AS criteria. SB features remained relevant for reclassification prediction even in case of positive TB. The risk of upstaged disease remains important, approximately one third, and neither TB/SB parameters nor MRI findings could accurately predict it.

Active surveillance eligibility of MRI-positive patients with grade group 2 prostate cancer: a pathological study

To assess the final pathology risk in MRI-positive grade group (GG) 2 prostate cancer (PCa) patients undergoing targeted (TB) and systematic (SB) biopsies, and thereby, the possibility of active surveillance (AS) in this population. We included 242 consecutive men diagnosed with GG2 PCa by a combination of SB and software-based fusion TB undergoing a radical prostatectomy (RP). The primary endpoints were the pathological findings in RP specimens, including favourable disease which was defined by a pT2 and GG1-2 disease. The rate of upgrading was 33% including 3% of GG 4-5 disease. MRI lesion size (p = 0.038) and tumor length per core (p < 0.001) were significantly lower in case of favourable pathology. Only 34.2% of not organ-confined disease was reported when only SB were positive, compared with 45.7% and 57.1% when GG2 was detected on TB only and on TB plus SB, respectively (p = 0.035). The number of positive cores on SB was significantly higher in not organ-confined disease (4.3 versus 2.9; p = 0.005). The risk of not organ-confined disease was only 20.8% in men who had a PSAD ≤ 0.20ng/ml/gr, 1-2 positive biopsies and a maximal tumor length ≤ 6mm per core, compared with 52.3% in men who did not fulfil all these criteria (p = 0.003). This study identified clinical, imaging, and pathological factors that were significantly associated with the final pathology risk. In case of positive MRI followed by TB showing GG2, AS could be offered in patients having a PSAD ≤ 0.20, a tumor length ≤ 6mm and 1-2 positive cores.

Performance of systematic, MRI-targeted biopsies alone or in combination for the prediction of unfavourable disease in MRI-positive low-risk prostate cancer patients eligible for active surveillance.

To assess the upstaging/upgrading rates of low-risk prostate cancer (PCa) according to the biopsy scheme used (systematic (SB), targeted biopsies (TB), or both) in the setting of positive pre-biopsy MRI. We included 143 consecutive men fulfilling the Toronto University active surveillance (AS) criteria who underwent a pre-biopsy positive MRI, a combination of SB and software-based fusion TB, and a radical prostatectomy, in two expert centres. The primary endpoints were the pathological upgrading and upstaging rates. Overall unfavourable disease (OUD) was defined by any pT3-4 and/or pN1 and/or ≥ GG 3. Using TB alone would have missed 21.7% of cancers including 16.7% of ≥ GG 3. The use of TB was significantly associated with a lower risk of ≥ Grade Group (GG) 3 disease (p < 0.006) in RP specimens. Combination of SB and TB lowered this risk by 39%, compared with TB alone. The biopsy scheme did not affect the upstaging rates which were substantial even in case of combination scheme (from 37 to 46%). OUD was detected in approximately 50% of cases. The presence of high grade on TB was the only independent predictive factor for both ≥ GG 2 (p = 0.015) and ≥ GG 3 (p = 0.023) in RP specimens. High grade on TB biopsies represented the major predictor of upgrading. Combination of SB and TB better defined the sub-group of patients having the lowest risk of reclassification, compared with TB or SB alone. The risk of non-organ-confined disease remained high, and could not be accurately predicted by MRI or systematic/targeted biopsy features.

Co-registration of MRI and ultrasound: accuracy of targeting based on radiology-pathology correlation.

We reviewed the role of multiparametric magnetic resonance imaging (MP-MRI) and methods of MRI guided biopsy including in-bore, cognitive fusion, and software-based fusion. MP-MRI has been developed, optimized, and studied as a means of improving prostate cancer detection beyond the standard evaluation that utilizes digital rectal examinations and serum prostate specific antigen (PSA). MP-MRI has been proven to be an excellent diagnostic imaging modality that improves prostate cancer detection and risk stratification by guiding biopsy samples. The co-registration between MRI and ultrasound has allowed for software-based fusion which enables office-based biopsy procedures while still benefiting from the detailed prostate characterization of MRI. MP-MRI/ultrasound fusion guided biopsy has been studied in detail as this technology has been developed, tested, and validated in the past decade. The imaging to pathology correlation supporting the use of MP-MRI/ultrasound fusion is well documented in the literature. As the indication for the use of prostate MP-MRI becomes more widespread, it is important to continue to evaluate the correlation between imaging and pathologic findings.

Diagnostic accuracy of ultrasound, 18F-FDG-PET/CT, and fused 18F-FDG-PET-MR images with DWI for the detection of cervical lymph node metastases of HNSCC

This study aimed to compare (18)F-fluorodesoxyglucose positron emission tomography/MRI ((18)F-FDG-PET-MRI) fusion images, including diffusion-weighted imaging (DWI), (18)F-FDG-PET/CT, and ultrasound (US) regarding their performance in nodal staging of patients with head and neck squamous cell carcinoma (HNSCC). Eighteen patients prospectively underwent ultrasound examination, (18)F-FDG- PET/CT, and MRI before oral tumor resection and bilateral neck dissection. PET data sets were fused with contrast-enhanced T1-weighted MR images. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for nodal detection were calculated for all the imaging modalities. Furthermore, the accuracy of the correct N-staging was calculated for all methods. Detailed histopathology served as the standard of reference. The sensitivity, specificity, PPV, NPV, and accuracy for detection of lymph node metastases were 63, 99, 86, 96, and 95 % for ultrasound; 30, 97, 56, 92, and 90 % for (18)F-FDG-PET/CT; 52, 96, 59, 94, and 91 % for (18)F-FDG-PET-MRI; and 53, 97, 67, 95, and 92 % for (18)F-FDG-PET-MRI plus DWI, respectively. There was no significant difference in the diagnostic accuracy for lymph node metastasis detection between (18)F-FDG-PET-MRI and (18)F-FDG-PET/CT (p = 0.839) and between (18)F-FDG-PET-MRI plus DWI and (18)F-FDG-PET/CT (p = 0.286), respectively. US was significantly more accurate than (18)F-FDG-PET/CT (p = 0.009), whereas no significant difference was seen between (18)F-FDG-PET-MRI and US (p = 0.223) or (18)F-FDG-PET-MRI plus DWI and US (p = 0.115). The nodal stage was correctly rated by (18)F-FDG-PET-MRI in eight patients, (18)F-FDG-PET-MRI plus DWI in nine patients, US in 12 patients, and (18)F-FDG-PET/CT in five out of 18 patients. Software-based fusion of (18)F-FDG-PET-MRI and (18)F-FDG-PET-MRI plus DWI may not increase nodal detection and N-staging performance in patients with oral malignancies compared to US and (18)F-FDG-PET/CT. Surgical staging of cervical lymph nodes will not be replaced even by advanced imaging modalities in the near future.

Prosthetic vascular graft infection imaging

PurposeWe are reporting our experience with imaging of vascular graft infections using computed tomography angiography (CTA), white blood cell (WBC) scintigraphy and software-based fusion imaging. Material and methodsInstitutional review board approval was obtained. We performed a retrospective review of patients who had clinical signs and symptoms of vascular graft infection in whom both WBC single photon emission computed tomography (SPECT) and CTA was performed between 2005 and 2010. We performed fusion imaging with available data using software coregistration technique and analyzed outcome of the patients. ResultsWe had 20 patients; 11 had grafts of the aorta, five had peripheral vascular grafts, three had aortic and peripheral vascular grafts, and one had a thoracic aortic graft. WBC imaging was positive in 10 patients, negative in six patients and indeterminate in 4 patients. CTA was positive in six patients, negative in four patients and indeterminate in 10 patients. Sensitivity, specificity, accuracy, positive predictive value and negative predictive value (NPV) for WBC, CTA and WBC SPECT/CTA fusion were 75/100/80/100/50%, 88/50/80/88/50% and 94/50/85/88/67% respectively. ConclusionThe use of CTA, WBC scintigraphy, and image co-registration influenced the diagnostic confidence of graft infection and the outcome of the patients. Software-based fusion imaging of both modalities resulted in improved sensitivity, accuracy, and NPV.

Anatomical accuracy of abdominal lesion localization

SummarySoftware-based image registration can improve the diagnostic value of imaging procedures and is an alternative to hybrid scanners. The aim of this study was to evaluate the anatomical accuracy of automatic rigid image registration of independently acquired datasets of positron emission tomography with 18F-deoxyglucose and abdominal magnetic resonance imaging. Patients, methods: Analyses were performed on 28 abdominal lesions from 20 patients. The PET data were obtained using a stand-alone PET camera in 14 cases and a hybrid PET/CT scanner in 9 cases. The abdominal T1- and T2-weighted MRI scans were acquired on 1.5 T MRI scanners. The mean time interval between MRI and PET was 7.3 days (0–28 days). Automatic rigid registration was carried out using a self-developed registration tool integrated into commercial available software (InSpace for Siemens Syngo). Distances between the centres of gravity of 28 manually delineated neoplastic lesions represented in PET and MRI were measured in X-, Y-, and Z-direction. The intra- (intraclass correlation 0.94) and inter- (intraclass correlation 0.86) observer repeatability were high. Results: The average distance in all MRI sequences was 5.2 ± 7.6 mm in X-direction, 4.0 ± 3.7 mm in Y-direction and 6.1 ± 5.1 mm in Z-direction. There was a significantly higher misalignment in Z-direction (p &lt; 0.05). The misalignment was not significantly different for the registration of T1- and T2- weighted sequences (p = 0.7). Conclusion: The misalignment between FDG-PET and abdominal MRI registered using an automated rigid registration tool was comparable to data reported for software-based fusion between PET and CT. Although this imprecision may not affect diagnostic accuracy, it is not sufficient to allow for pixel-wise integration of MRI and PET information.

Hybrid cardiac imaging: SPECT/CT and PET/CT. A joint position statement by the European Association of Nuclear Medicine (EANM), the European Society of Cardiac Radiology (ESCR) and the European Council of Nuclear Cardiology (ECNC)

Improvements in software and hardware have enabled the integration of dual imaging modalities into hybrid systems, which allow combined acquisition of the different data sets. Integration of positron emission tomography (PET) and computed tomography (CT) scanners into PET/CT systems has shown improvement in the management of patients with cancer over stand-alone acquired CT and PET images. Hybrid cardiac imaging either with single photon emission computed tomography (SPECT) or PET combined with CT depicts cardiac and vascular anatomical abnormalities and their physiologic consequences in a single setting and appears to offer superior information compared with either stand-alone or side-by-side interpretation of the data sets in patients with known or suspected coronary artery disease (CAD). Hybrid systems are also advantageous for the patient because of the single short dual data acquisition. However, hybrid cardiac imaging has also generated controversy with regard to which patients should undergo such integrated examination for clinical effectiveness and minimization of costs and radiation dose, and if software-based fusion of images obtained separately would be a useful alternative. The European Association of Nuclear Medicine (EANM), the European Society of Cardiac Radiology (ESCR) and the European Council of Nuclear Cardiology (ECNC) in this paper want to present a position statement of the institutions on the current roles of SPECT/CT and PET/CT hybrid cardiac imaging in patients with known or suspected CAD.

Software-based Fusion of PET and CT Images for Suspected Recurrent Lung Cancer

The purpose of this study was to compare the diagnostic performance of the manual fusion of positron emission tomography (PET) and computed tomography (CT) images with that of CT alone and that of side-by-side PET and CT (PET/CT) in patients with suspected recurrent lung cancer. Fifty-three patients who had previously had surgery for lung cancer underwent a whole-body 2-deoxy-2-[F-18]fluoro-D-glucose (FDG)-PET scan, followed by a diagnostic CT scan. The PET and CT images were fused on a workstation. CT alone, PET/CT, and fused images were evaluated separately using a five-point grading scale (0=definitely negative, 1=probably negative, 2=equivocal, 3=probably positive, and 4=definitely positive). Lesions of grade 3 or 4 were considered positive, and diagnostic accuracy and certainty were evaluated. Overall, 67 lesions in 33 patients were considered true positive pathologically or clinically. Of these 67 lesions, the evaluation of CT, PET/CT, and fused images detected 46, 55, and 66 lesions, respectively, with the number of grade 4 lesions detected being 38, 50, and 63, respectively. The diagnostic accuracy of CT, PET/CT, and fused images according to patients was 75%, 79%, and 87%, respectively. These results suggest that interpreting fused images increased diagnostic certainty for detecting recurrence and provided more accurate diagnoses.

Functional-anatomical image fusion in neuroendocrine tumors.

Nuclear medicine provides physiologic and functional data for normal and pathologic organs but often the clear definition of the sites of radiotracers' uptake are difficult. Radiological methods are able to identify structural changes in a detailed way, but do not give precise information on function of organs or pathologic lesions. The registration and fusion of nuclear medicine studies with structural information obtained by radiological exams allows the precise correlation of functional and anatomical data. Software-based fusion of independently performed nuclear medicine and morphologic studies is uncertain of success and the alignment procedures are labor intensive. Recently, a new imaging device combining a dual-head, variable angle gamma camera with a low-dose x-ray tube has been introduced; the acquired single-photon emission computed tomography (SPECT) and x-ray computed tomography (CT) images are coregistered by means of the hardware in the same session. This new technology can be particularly useful when applied to scintigraphic procedures in neuroendocrine tumors. In-111 pentetreotide and radiolabeled MIBG play an important role in the study of patients with these tumors; the addition of anatomical maps provides a precise localization of SPECT findings and allows the exclusion of disease in sites of physiologic tracer uptake. SPECT/CT fused images are able to provide additional information that improves the accuracy of SPECT interpretation and leads to changes in therapeutic options, so enhancing the clinical role of nuclear medicine in evaluating patients with neuroendocrine tumors.

Fusion imaging in nuclear medicine--applications of dual-modality systems in oncology.

Medical imaging has become of the utmost importance in evaluating patients with cancer. Single-photon emission computed tomography (SPECT) and positron emission tomography (PET) are accurate methods for detecting cancer and related metabolic abnormalities, but they often do not provide the anatomical landmarks needed to precisely localize lesions. Magnetic resonance imaging (MRI) and computed tomography (CT) scan, on the other hand, offer excellent anatomic detail but are less sensitive because they do not provide functional detail. Fusion imaging combines functional studies with morphological ones, so overcoming the drawbacks of both modalities. Software-based fusion of independently performed scintigraphic and radiological images has proven time consuming and impractical for routine use. Recently, dual-modality integrated imaging systems (SPECT/CT and PET/CT) have been developed: the acquired images are coregistered by means of the hardware in the same session. These new devices can be particularly useful for tumour imaging. The anatomical images provide precise localization and allow the exclusion of disease in sites of physiologic tracers' accumulation for SPECT and PET findings. Hybrid imaging in oncological applications has been very encouraging, indicating that these systems are suited for routine use in clinical practice. In fact, fused images provide additional information that improves diagnostic accuracy and impacts on patient management.