J. L. Bloem

Monitoring the effect of chemotherapy in Ewing's sarcoma of bone with MR imaging

Magnetic resonance (MR) imaging was performed in 26 patients with Ewings sarcoma of bone preceding and following neoadjuvant chemotherapy, to assess tumour response non-invasively prior to surgery. T1- and T2-weighted spin echo images were obtained. Changes including intra- and extramedullary signal intensities, tumour demarcation, tumour volume and the appearance of residual extramedullary tumour were compared with histopathology of the resected specimens. Reduction of tumour volume was significantly higher in good responders. Other single parameters did not correlate with histologic tumour response. However, when several MR parameters summarized in a classification system were combined, a positive correlation with histopathologic response was found. A limited decrease of tumour volume (<25%) and/or residual soft tissue mass following chemotherapy correlated with a poor response. An inhomogeneous, well-defined cuff of abnormal tissue encircling the bone and/or radiological disappearance of the soft tissue tumour component following chemotherapy correlated with good response. Twenty-three out of 26 patients were correctly classified by MR as good or poor responders. Minimal residual disease (<10% of the entire tumour volume), observed histologically, could not be identified with MR imaging. Tumour volume reduction and residual extramedullary tumour, rather than changes of signal intensity, are major features for evaluating the response to chemotherapy in Ewings sarcoma.

Can conventional radiographs be used to monitor the effect of neoadjuvant chemotherapy in patients with osteogenic sarcoma

Abstractu2002Objective. The objective of this study was to assess the effectiveness of conventional radiography in predicting histopathologic response in patients with osteogenic sarcoma who were treated with preoperative chemotherapy. Design and patients. The radiographs of 22 patients with an osteogenic sarcoma, taken before and after neoadjuvant chemotherapy, were reviewed. Tumour location, size, radiographic appearance, margination, cortical destruction and periosteal reaction were evaluated. The findings were correlated with the histopathologic response of the surgical specimen. Results. None of the findings proved to be of predictive value for the histopathologic response. Increase in tumour diameter and increase in ossification and/or calcification, which were seen in more than half of the patients, did not correlate with response. Conclusion. Conventional radiographs do not contribute to the identification of good or poor responders.

Classification of histopathologic changes following chemotherapy in Ewing's sarcoma of bone

A uniform classification of response to chemotherapy is essential to allow comparison of local effect and ultimate prognosis between different therapy schedules. We define a histological grading system for assessment of the response to chemotherapy in Ewings sarcoma, based on the amount and architectural pattern of residual histologically viable-appearing tumour, the preferential sites of minimal residual tumour and the amount of tumour necrosis. Twenty-six consecutive patients with a biopsy-proven Ewings sarcoma were treated with chemotherapy prior to surgery. The effect of chemotherapy was evaluated microscopically on the specimens obtained after surgery. Response to chemotherapy was classified as minimal or no effect (<10% tumour necrosis), moderate effect (solid areas of remnant viable tumour), minimal residual disease, and no evidence of disease (100% tumour necrosis or well-vascularized fibrous tissue). The subperiosteal area in particular, and, less frequently, soft tissues and intramedullary compartment were identified as sites of predilection for persistence of microscopic viable tumour foci, frequently depicted as pseudo-rosettes in a characteristic scattered pattern. Although it is not well known whether morphological viability of these residual clusters in Ewings sarcoma indicates biological viability, accurate preoperative local staging, with special attention to preferential sites of residual viable tumour, is essential. The proposed grading system can be used to standardize assessment of chemotherapy in trials, and may serve as a standard for non-invasive monitoring of preoperative chemotherapy with magnetic resonance imaging.

Magnetic resonance relaxation times of normal tissue in the course of chemotherapy: a study in patients with bone sarcoma

To study the effect of chemotherapy on normal fat, skeletal muscle, and bone marrow, T1 and T2 relaxation times were measured in 15 patients with bone sarcoma before and after each cycle of preoperative chemotherapy. A section plane containing the tumor and if possible the nonaffected extremity was imaged with combined multiecho spin echo and inversion recovery pulse sequences. T1 and T2 relaxation times were calculated in the normal-appearing tissues. Although some variation was found in the values in the individual patient and between patients, no systematic changes of relaxation times of fat, muscle, or bone marrow occurred in the course of treatment. We conclude that the chemotherapy used in bone sarcoma has no effect on relaxation times of normal fat, muscle, and bone marrow, and that therefore these tissues may serve as a reference for the signal intensity of tumor.

Segmentation of Dynamic Contrast-Enhanced MR-Images of Post Chemotherapy Ewing’s Sarcoma with a Pharmacokinetic Model and a Neural Network

Most patients with Ewing’s sarcoma undergo neoadjuvant (preoperative) chemotherapy before surgery is performed. Generally, chemotherapy reduces the size of the tumor which makes the subsequent treatment more successful. MR-imaging aims at monitoring the effect of chemotherapy by identifying areas of vital remnant tumor. An MR-examination includes static T1- and T2-weighted MR-images as well as dynamic, contrast-enhanced T1-weighted MR-images. Whereas the static MR-images are used to estimate the volume of intra- and extra-osseous bone tumor, the dynamic contrast-enhanced MR-sequence indicates which parts of the tumor are highly perfused by blood. In general, malignant bone tumors are highly perfused. Moreover, these lesions are heterogenuous (sometimes multifocal) containing viable as well as nonviable (necrotic) parts. The only way to reliably distinguish viable from nonviable tumor tissue is by performing a perfusion study by dynamic contrast-enhanced MRI [1].

Tumoren und tumorähnliche Läsionen des Kniegelenkes

Die schnelle Entwicklung der bildgebenden Verfahren hat in den letzten Jahren einen entscheidenden Einflus auf die Behandlung primarer maligner Knochentumorengenommen. Die klassischen ablativen Operationverfahren sind uberwiegend durch Kombinationstherapien wie (neo-)adjuvante Chemotherapie, Strahlentherapie, lokale Resektion und rekonstruktive operative Verfahren ersetzt worden. Derzeit werden etwa 80% unserer Patienten mit primaren muskuloskeletalen Tumoren primar durch lokale Operationsverfahren anstelle einer Amputation oder Exartikulation behandelt. Nur nach genauem praoperativem Staging mit Hilfe von bildgebenden Verfahren ist eine extremitatenerhaltende Operation moglich, die zugleich eine gute residuelle Funktion erhalt. Das genaue Tumorstaging ist somit der wichtigste Grund, bei Patienten mit muskuloskelettalen Tumoren praoperativ eine MRT durchzufuhren [7]. Weiter sind der Nachweis, die spezifische Diagnose, das Monitoring der Chemotherapie und der Nachweis von Rezidiven wichtige Indikationen zur MRT bei diesen Patienten, wobei die letzten beiden Indikationen zunehmende Bedeutung erlangt haben. In diesem Kapitel werden die technischen Aspekte, die Problematik des lokalen Tumorstagings und schlieslich die wichtigsten Aspekte der Tumoren der Kniegelenkregion besprochen.