Improved early outcome prediction by MRI-based 3D tumor volume assessment in patients with CNS lymphomas

BACKGROUND

Central nervous system lymphomas (CNSL) display remarkable clinical heterogeneity, yet accurate prediction of outcomes remains challenging. The IPCG criteria are widely used in routine practice for the assessment of treatment response. However, the value of the IPCG criteria for ultimate outcome prediction is largely unclear, mainly due to the uncertainty in delineating complete from partial responses during and after treatment.

METHODS

We explored various MRI features including semi-automated 3D tumor volume measurements at different disease milestones and their association with survival in 93 CNSL patients undergoing curative-intent treatment.

RESULTS

At diagnosis, patients with more than 3 lymphoma lesions, periventricular involvement, and high 3D tumor volumes showed significantly unfavorable PFS and OS. At first interim MRI during treatment, the IPCG criteria failed to discriminate outcomes in responding patients. Therefore, we randomized these patients into training and validation cohorts to investigate whether 3D tumor volumetry could improve outcome prediction. We identified a 3D tumor volume reduction of ≥97% as the optimal threshold for risk stratification (=3D early response, 3D_ER). Applied to the validation cohort, patients achieving 3D_ER had significantly superior outcomes. In multivariate analyses, 3D_ER was independently prognostic of PFS and OS. Finally, we leveraged prognostic information from 3D MRI features and circulating biomarkers to build a composite metric that further improved outcome prediction in CNSL.

CONCLUSIONS

We developed semi-automated 3D tumor volume measurements as strong and independent early predictors of clinical outcomes in CNSL patients. These radiologic features could help improve risk stratification and help guide future treatment approaches.

Intratumoral heterogeneity after targeted therapy in murine cancer models with differing degrees of malignancy

INTRODUCTION

Conventional morphologic and volumetric assessment of treatment response is not suitable for adequately assessing responses to targeted cancer therapy. The aim of this study was to evaluate changes in tumor composition after targeted therapy in murine models of breast cancer with differing degrees of malignancy via non-invasive magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Mice bearing highly malignant 4T1 tumors or low malignant 67NR tumors were treated with either a combination of two immune checkpoint inhibitors (ICI, anti-PD1 and anti-CTLA-4) or the multi-tyrosine kinase inhibitor sorafenib, following experiments with macrophage-depleting clodronate-loaded liposomes and vessel-stabilizing angiopoietin-1. Mice were imaged on a 9.4 T small animal MRI system with a multiparametric (mp) protocol, comprising T1 and T2 mapping and diffusion-weighted imaging. Tumors were analyzed ex vivo with histology.

RESULTS AND DISCUSSIONS

All treatments led to an increase in non-viable areas, but therapy-induced intratumoral changes differed between the two tumor models and the different targeted treatments. While ICI treatment led to intratumoral hemorrhage, sorafenib treatment mainly induced intratumoral necrosis. Treated 4T1 tumors showed increasing and extensive areas of necrosis, in comparison to 67NR tumors with only small, but also increasing, necrotic areas. After either of the applied treatments, intratumoral heterogeneity, was increased in both tumor models, and confirmed ex vivo by histology. Apparent diffusion coefficient with subsequent histogram analysis proved to be the most sensitive MRI sequence. In conclusion, mp MRI enables to assess dedicated therapy-related intratumoral changes and may serve as a biomarker for treatment response assessment.

MRI-Guided Targeted and Systematic Prostate Biopsies as Prognostic Indicators for Prostate Cancer Treatment Decisions

The standard procedure for the diagnosis of prostate carcinoma involves the collection of 10-12 systematic biopsies (SBx) from both lobes. MRI-guided targeted biopsies (TBx) from suspicious foci increase the detection rates of clinically significant (cs) PCa. We investigated the extent to which the results of the TBx predicted the tumor board treatment decisions. SBx and TBx were acquired from 150 patients. Risk stratifications and recommendations for interventional therapy (prostatectomy and radiotherapy) or active surveillance were established by interdisciplinary tumor boards. We analyzed how often TBx alone were enough to correctly classify the tumors as well as to indicate interventional therapy and how often the findings of SBx were crucial for therapy decisions. A total of 28/39 (72%) favorable risk tumors were detected in TBx, of which 11/26 (42%) very-low-risk tumors were not detected and 8/13 (62%) low-risk tumors were undergraded. A total of 36/44 (82%) intermediate-risk PCa were present in TBx, of which 4 (9%) were underdiagnosed as a favorable risk tumor. A total of 12/13 (92%) high-risk carcinomas were detected and correctly grouped in TBx. The majority of csPCa were identified by the sampling of TBx alone. The tumor size was underestimated in a proportion of ISUP grade 1 tumors. Systematic biopsy sampling is therefore indicated for the next AS follow-up in these cases.

Circulating Tumor DNA Profiling for Detection, Risk Stratification, and Classification of Brain Lymphomas

PURPOSE

Clinical outcomes of patients with CNS lymphomas (CNSLs) are remarkably heterogeneous, yet identification of patients at high risk for treatment failure is challenging. Furthermore, CNSL diagnosis often remains unconfirmed because of contraindications for invasive stereotactic biopsies. Therefore, improved biomarkers are needed to better stratify patients into risk groups, predict treatment response, and noninvasively identify CNSL.

PATIENTS AND METHODS

We explored the value of circulating tumor DNA (ctDNA) for early outcome prediction, measurable residual disease monitoring, and surgery-free CNSL identification by applying ultrasensitive targeted next-generation sequencing to a total of 306 tumor, plasma, and CSF specimens from 136 patients with brain cancers, including 92 patients with CNSL.

RESULTS

Before therapy, ctDNA was detectable in 78% of plasma and 100% of CSF samples. Patients with positive ctDNA in pretreatment plasma had significantly shorter progression-free survival (PFS, P < .0001, log-rank test) and overall survival (OS, P = .0001, log-rank test). In multivariate analyses including established clinical and radiographic risk factors, pretreatment plasma ctDNA concentrations were independently prognostic of clinical outcomes (PFS HR, 1.4; 95% CI, 1.0 to 1.9; P = .03; OS HR, 1.6; 95% CI, 1.1 to 2.2; P = .006). Moreover, measurable residual disease detection by plasma ctDNA monitoring during treatment identified patients with particularly poor prognosis following curative-intent immunochemotherapy (PFS, P = .0002; OS, P = .004, log-rank test). Finally, we developed a proof-of-principle machine learning approach for biopsy-free CNSL identification from ctDNA, showing sensitivities of 59% (CSF) and 25% (plasma) with high positive predictive value.

CONCLUSION

We demonstrate robust and ultrasensitive detection of ctDNA at various disease milestones in CNSL. Our findings highlight the role of ctDNA as a noninvasive biomarker and its potential value for personalized risk stratification and treatment guidance in patients with CNSL.

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Application of diffusion microstructure imaging in musculoskeletal radiology - translation from head to shoulders

OBJECTIVES

Quantitative MRI techniques, such as diffusion microstructure imaging (DMI), are increasingly applied for advanced tissue characterization. We determined its value in rotator cuff (RC) muscle imaging by studying the association of DMI parameters to isometric strength and fat fraction (FF).

METHODS

Healthy individuals prospectively underwent 3T-MRI of the shoulder using DMI and chemical shift encoding-based water-fat imaging. RC muscles were segmented and quantitative MRI metrics (V-ISO, free fluid; V-intra, compartment inside of muscle fibers; V-extra, compartment outside of muscle fibers, and FF) were extracted. Isometric shoulder strength was quantified using specific clinical tests. Sex-related differences were assessed with Student's t. Association of DMI-metrics, FF, and strength was tested. A factorial two-way ANOVA was performed to compare the main effects of sex and external/internal strength-ratio and their interaction effects on quantitative imaging parameters ratios of infraspinatus/subscapularis.

RESULTS

Among 22 participants (mean age: 26.7 ± 3.1 years, 50% female, mean BMI: 22.6 ± 1.9 kg/m²), FF of the individual RC muscles did not correlate with strength or DMI parameters (all p > 0.05). Subjects with higher V-intra (r = 0.57 to 0.87, p < 0.01) and lower V-ISO (r = -0.6 to -0.88, p < 0.01) had higher internal and external rotation strength. Moreover, V-intra was higher and V-ISO was lower in all RC muscles in males compared to female subjects (all p < 0.01). There was a sex-independent association of external/internal strength-ratio with the ratio of V-extra of infraspinatus/subscapularis (p = 0.02).

CONCLUSIONS

Quantitative DMI parameters may provide incremental information about muscular function and microstructure in young athletes and may serve as a potential biomarker.

KEY POINTS

• Diffusion microstructure imaging was successfully applied to non-invasively assess the microstructure of rotator cuff muscles in healthy volunteers. • Sex-related differences in the microstructural composition of the rotator cuff were observed. • Muscular microstructural metrics correlated with rotator cuff strength and may serve as an imaging biomarker of muscular integrity and function.

Transitioning the Molecular Tumor Board from Proof of Concept to Clinical Routine: A German Single-Center Analysis

Molecular precision oncology faces two major challenges: first, to identify relevant and actionable molecular variants in a rapidly changing field and second, to provide access to a broad patient population. Here, we report a four-year experience of the Molecular Tumor Board (MTB) of the Comprehensive Cancer Center Freiburg (Germany) including workflows and process optimizations. This retrospective single-center study includes data on 488 patients enrolled in the MTB from February 2015 through December 2018. Recommendations include individual molecular diagnostics, molecular stratified therapies, assessment of treatment adherence and patient outcomes including overall survival. The majority of MTB patients presented with stage IV oncologic malignancies (90.6%) and underwent an average of 2.1 previous lines of therapy. Individual diagnostic recommendations were given to 487 patients (99.8%). A treatment recommendation was given in 264 of all cases (54.1%) which included a molecularly matched treatment in 212 patients (43.4%). The 264 treatment recommendations were implemented in 76 patients (28.8%). Stable disease was observed in 19 patients (25.0%), 17 had partial response (22.4%) and five showed a complete remission (6.6%). An objective response was achieved in 28.9% of cases with implemented recommendations and for 4.5% of the total population (22 of 488 patients). By optimizing the MTB workflow, case-discussions per session increased significantly while treatment adherence and outcome remained stable over time. Our data demonstrate the feasibility and effectiveness of molecular-guided personalized therapy for cancer patients in a clinical routine setting showing a low but robust and durable disease control rate over time.

Revised FIGO Staging for Cervical Cancer - A New Role for MRI

Cervical cancer is still the fourth most common malignancy in women worldwide and has a high mortality rate. The prognosis as well as the therapy depends largely on the extent of the tumor at the time of initial diagnosis. This shows the importance of correct staging of cervical cancer. In order to promote a globally uniform approach, staging of cervical cancer in the past was based on widespread examinations such as exam under anesthesia, histology from cervical conization or biopsy, systematic lymphadenectomy, cystoscopy, proctoscopy, i. v.-pyelogram and chest X-ray. However, as the primary tumor stage was often underestimated, the 2018 revised FIGO classification now permits cross-sectional imaging techniques and pathological findings to be incorporated into disease staging or an already existing stage to be adapted based on radiological findings. Thanks to its excellent soft tissue contrast, magnetic resonance imaging (MRI) is the method of choice for local-regional staging of cervical cancer, evaluating the response to treatment, detecting tumor recurrence and for follow-up examinations. It is important that radiologists interpreting pelvic MRI in case of suspected cervical cancer are familiar with the current FIGO staging system. This is the only way to determine the tumor stage as precisely as possible and thus lay the foundation for the success of therapy for patients. The aim of this review is to present the changes of the revised FIGO classification as well as to show the importance of MRI as the method of choice for local-regional tumor staging as a complement to clinical examination. KEY POINTS::   · Cervical cancer is still the world's fourth most common female cancer and has a high mortality rate.. · The FIGO classification for staging cervical cancer in the past was based on clinical and widespread examinations.. · The primary tumor stage has often been underestimated with the FIGO staging system since 2018.. · Since 2018, cross-sectional imaging techniques have been incorporated into disease staging.. · MRI is the method of choice for local-regional tumor staging, evaluation of the response to treatment, detection of tumor recurrence and possible complications.. CITATION FORMAT: · Merz J, Bossart M, Bamberg F et al. Revised FIGO Staging for Cervical Cancer - A New Role for MRI. Fortschr Röntgenstr 2020; 192: 937 - 944.

Work and Training Conditions of German Residents in Radiology - Results from a Nationwide Survey Conducted by the Young Radiology Forum in the German Roentgen Society

PURPOSE

 Good training is the basis for high job satisfaction and high-quality patient care in radiology. The aim of this survey was to record the current state of working conditions for residents in radiology training in Germany and to focus on the aspects of training and psychosocial workload. The description of the actual state should help to identify possible problem areas and to develop improvement approaches.

MATERIALS AND METHODS

 At the beginning of 2018, we sent an electronic questionnaire to the German Roentgen Society (DRG), the German Association of Chairmen in Academic Radiology (KLR), the Chief Physician Forum of the DRG (CAFRAD) and the Forum of Registered Radiologists (FUNRAD) with the request to forward it to radiology residents. With 63 questions, the questionnaire covered seven essential areas of medical working and training conditions. In order to ensure interdisciplinary comparability, most questions were identical to previous surveys among residents of other disciplines.

RESULTS

 643 residents started the survey. 501 (78 %) questionnaires were fully processed and included in the final analysis. 65 % of respondents were satisfied with their current job situation. At the same time, shortcomings, especially with regard to the reconciliation of family and work as well as scientific and clinical work, became clear. Only 36 % of participants with children were satisfied with the compatibility of family and work at their workplace. Only 31 % of the researchers were satisfied with their research conditions. In addition, residents experienced a high psychosocial workload.

CONCLUSION

 Job satisfaction is high among radiology residents in direct comparison to other disciplines. However, based on this survey, adjustments to working conditions and training in radiology seem necessary to maintain the health of the physicians concerned, to encourage motivation for scientific work and to enhance development opportunities, especially for women, through a better compatibility of work and family life. The present survey identifies strategies and leadership tools that can help to achieve this.

KEY POINTS

 Residents in radiology training ... · have a relatively high job satisfaction.. · experience a high psychosocial workload.. · evaluate the compatibility of family and work as in need of improvement.. · are interested in research, but evaluate research conditions as insufficient.

CITATION FORMAT

· Oechtering TH, Panagiotopoulos N, Völker M et al. Work and Training Conditions of German Residents in Radiology - Results from a Nationwide Survey Conducted by the Young Radiology Forum in the German Roentgen Society. Fortschr Röntgenstr 2020; 192: 458 - 469.

Target-Specific Imaging of Cathepsin and S100A8/A9 Reflects Specific Features of Malignancy and Enables Estimation of Tumor Malignancy

PURPOSE

Tumor development and metastasis are dependent on tumor infiltrating immune cells which form a characteristic tumor microenvironment (TME). Activated monocytes secrete the protein heterodimer S100A8/A9 promoting TME formation. Monocyte-dependent proteases facilitate local tumor cell invasion by degradation of the extracellular matrix. We aimed for target specific in vivo imaging of S100A8 and proteases to provide differentiating biomarkers for local tumor growth and metastatic potential.

PROCEDURES

Murine breast cancer cells of the 4T1 model with graduated metastatic potential (4T1 and 4T07: both hematogenous metastasis > 168FAR: lymph-node metastasis > 67NR: no metastasis) were orthotopically implanted into female BALB/c mice. At 4 mm size, tumors were investigated by injecting the protease-specific probe ProSense 750EX (PerkinElmer, 4T1 n = 7, 4T07 n = 10, 168FAR n = 16, 67NR n = 15) and anti-S100A8-Cy5.5 (n = 6 each) and performing fluorescence reflectance imaging at 0 and 24 h after injection. In vivo imaging was validated with immunohistochemistry.

RESULTS

At 24 h, S100A8-specific signals in 4T1 and 4T07 were significantly higher (1714.05/1683.45 AU) as compared to 168FAR and 67NR (174.85/167.95 AU, p = 0.0012/p = 0.0003), reflecting the capability of hematogenous spread. Protease-specific signals were significantly higher in 4T1 and 4T07 (348.01/409.93 AU) as compared to 168FAR (214.91 AU) and 67NR (129.78 AU p < 0.0001 each), reflecting local vessel invasion and tumor cell shedding. Immunohistology supported the in vivo imaging results.

CONCLUSIONS

Non-invasive in vivo imaging of S100A8 and monocytic proteases allows for differentiation of the tumors' local invasive and systemic metastatic potential in reflecting the TME formation. While proteases augment local tumor cell invasion, solid metastases seem to be dependent on a pro-tumoral microenvironment.

In Vivo Imaging of Pro- and Antitumoral Cellular Components of the Tumor Microenvironment

Tumor development and growth, as well as metastatic spread, are strongly influenced by various, mostly innate, immune cells, which are recruited to the tumor site and driven to establish a specific tumor-supportive microenvironment. The contents of this microenvironment, such as myeloid cells, are a major factor in the overall prognosis of malignant disease, addressed by a constantly growing armament of therapeutic interventions targeting tumor-supportive immune cells. Current clinical imaging has long ignored the growing need for diagnostic approaches addressing these microenvironmental contents-approaches enabling a sensitive and specific classification of tumor immune crosstalk and the resulting tumor-associated immune cell activity. In this focus article we review the present status of, and promising developments in, the in vivo molecular imaging of tumor immune components designed to allow for inferences to be made on the cross-talk between tumor cells and the immune system. Current imaging modalities based on the infiltrating cell types are briefly discussed.

Visualization of Tumor-Immune Interaction - Target-Specific Imaging of S100A8/A9 Reveals Pre-Metastatic Niche Establishment

Background Systemic cancer spread is preceded by the establishment of a permissive microenvironment in the target tissue of metastasis - the premetastatic niche. As crucial players in establishment of the pre-metastatic niche, myeloid derived suppressor cells (MDSC) release S100A8/A9, an exosomal protein that contributes to metastasis, angiogenesis, and immune suppression. We report the application of antibody-based single-photon emission computed tomography (SPECT) for detection of S100A8/A9 in vivo as an imaging marker for pre-metastatic tissue priming. Methods A syngeneic model system for invasive breast cancer with (4T1.2) or without (67NR) the tendency to form lung metastasis was established in BALB/c mice. A SPECT-probe has been generated and tested for visualization of S100A9 release. Tumor-associated changes in numbers and fuction of immune cells in pre-metastatic tissue were evaluated by flow cytometry and confocal microscopy. Results S100A8/A9 imaging reflected MDSC abundance and the establishment of an immunosuppressive environment in pre-metastatic lung tissue (activity 4T1.2 vs. healthy control: 0.95 vs. 0.45 %ID; p<0.001). The S100A8/A9 imaging signal in the pre-metastatic lung correlated with the subsequent metastatic tumor burden in the same organ (r2=0.788; p<0.0001). CCL2 blockade and the consecutive inhibition of premetastatic niche establishment was clearly depicted by S100A9-SPECT (lung activity untreated vs. treated: 2 vs, 1.4 %ID). Conclusion We report S100A8/A9 as a potent imaging biomarker for tumor-mediated immune remodeling with potential applications in basic research and clinical oncology.

c-Met PET Imaging Detects Early-Stage Locoregional Recurrence of Basal-Like Breast Cancer

Locoregional recurrence of breast cancer poses significant clinical problems because of frequent inoperability once the chest wall is involved. Early detection of recurrence by molecular imaging agents against therapeutically targetable receptors, such as c-Met, would be of potential benefit. The aim of this study was to assess (18)F-AH113804, a peptide-based molecular imaging agent with high affinity for human c-Met, for the detection of early-stage locoregional recurrence in a human basal-like breast cancer model, HCC1954.

METHODS

HCC1954 tumor-bearing xenograft models were established, and (18)F-AH113804 was administered. Distribution of radioactivity was determined via PET at 60 min after radiotracer injection. PET and CT images were acquired 10 d after tumor inoculation, to establish baseline distribution and uptake, and then on selected days after surgical tumor resection. CT images and caliper were used to determine the tumor volume. Radiotracer uptake was assessed by (18)F-AH113804 PET imaging. c-Met expression was assessed by immunofluorescence imaging of tumor samples and correlated with (18)F-AH113804 PET imaging results.

RESULTS

Baseline uptake of (18)F-AH113804, determined in tumor-bearing animals after 10 d, was approximately 2-fold higher in the tumor than in muscle tissue or the contralateral mammary fat pad. The tumor growth rate, determined from CT images, was comparable between the animals with recurrent tumors, with detection of tumors of low volume (<10 mm(3)) only possible by day 20 after tumor resection. (18)F-AH113804 PET detected local tumor recurrence as early as 6 d after surgery in the recurrent tumor-bearing animals and exhibited significantly higher (18)F-AH113804 uptake (in comparison to mammary fatty tissue), with a target-to-background (muscle) ratio of approximately 3:1 (P < 0.01). The c-Met expression of individual resected tumor samples, determined by immunofluorescence, correlated with the respective (18)F-AH113804 imaging signals (r = 0.82, P < 0.05).

CONCLUSION

(18)F-AH113804 PET provides a new diagnostic tool for the detection of c-Met-expressing primary tumor and has potential utility for the detection of locoregional recurrence from an early stage.

Optical in vivo imaging of the alarmin S100A9 in tumor lesions allows for estimation of the individual malignant potential by evaluation of tumor-host cell interaction

Tumors recruit and reprogram immune cells to support tumor development and spread, the most prominent among them being of monocytic origin such as tumor-associated macrophages (TAM) or myeloid-derived suppressor cells (MDSC). The alarmin S100A8/A9 has been implicated in the induction of TAM and MDSC. We assessed S100A9 as a molecular imaging marker for the activity of tumor-associated immune cells in a syngeneic murine breast cancer model. S100A9 could serve as a surrogate marker for tumor immune crosstalk as a function of malignancy, providing a tool with the potential for both basic research in tumor immunology and clinical stratification of patients.

METHODS

BALB/c mice were inoculated with murine breast cancer cells of common origin but different metastatic capability. At different times during tumor development, optical imaging was performed using a S100A9-specific probe to visualize activated monocytes. To further explore the impact of tumor-educated monocytes, splenic myeloid cells were isolated from either healthy or tumor-bearing animals and injected into tumor-bearing mice. We analyzed the effect of the cell transfer on immune cell activity and tumor development.

RESULTS

We could prove S100A9-driven imaging to sensitively and specifically reflect monocyte activity in primary tumor lesions. The imaging results were corroborated by histology and fluorescence-activated cell sorting analyses. In a prospective experiment, S100A9 imaging proved indicative of the individual tumor growth, with excellent correlation. Moreover, we could show that the monocyte activity as depicted by S100A9 activity in the primary tumor lesion mirrored the tumor's metastatic behavior. Treatment with tumor-primed splenic monocytes induced increased tumor growth, accompanied by an augmented infiltration of activated myeloid cells (MDSC and TAM) into the tumor. The consecutive S100A9 expression as depicted by in vivo imaging was significantly increased.

CONCLUSION

S100A9 proved to be a sensitive and specific marker for the activity of tumor-associated immune cells. To our knowledge, S100A9 imaging represents a first in vivo imaging approach for the estimation of recruitment and activity of tumor-associated myeloid immune cells. We demonstrated the potential value of this imaging approach for prediction of local and systemic tumor development.