Value of diffusion-weighted images in differentiating mid-course responders to chemotherapy for osteosarcoma compared to the histological response: preliminary results

BACKGROUND

Preoperative diffusion-weighted MRI (DW-MRI) has been described as an efficient method to differentiate good and poor responders to chemotherapy in osteosarcoma patients. A DW-MRI performed earlier during treatment could be helpful in monitoring chemotherapy.

OBJECTIVE

To assess the accuracy of DW-MRI in evaluating response to chemotherapy in the treatment of osteosarcoma, more specifically at mid-course of treatment.

MATERIALS AND METHODS

This study was carried out on a prospective series of adolescents treated for long-bone osteosarcoma. MR examinations were performed at diagnosis (MRI-1), at mid-course of chemotherapy (MRI-2), and immediately before surgery (MRI-3). A DW sequence was performed using diffusion gradients of b0 and b900. The apparent diffusion coefficients (ADC1, ADC2, ADC3, respectively), their differentials (ADC2 - ADC1 and ADC3 - ADC1), and their variation (ADC2 - ADC1/ADC1 and ADC3 - ADC1/ADC1) were calculated for each of these three time points.

RESULTS

Fifteen patients were included. Patients with no increase in ADC showed a poor response to chemotherapy on their histology results. At mid-course, the three calculated values were significantly different between good and poor responders. ADC2 - ADC1 enabled us to detect, with 100% specificity, four out of seven of the poor responders. There was no significant difference in the values at MRI-3 between the two groups.

CONCLUSION

DW-MRI performed both at baseline and mid-course of neoadjuvant chemotherapy is an efficient method to predict further histological response of osteosarcoma. This method could be used as an early prognostic factor to monitor preoperative chemotherapy.

Diffusion-weighted magnetic resonance imaging with apparent diffusion coefficient (ADC) determination in normal and pathological fetal kidneys

OBJECTIVES

To assess the use of diffusion-weighted magnetic resonance imaging (DW-MRI) in the evaluation of the fetal kidney and to estimate age-dependent changes in the apparent diffusion coefficient (ADC) of normal and pathological fetal kidneys.

METHODS

DW-MRI was performed on a 1.5-T machine at 23-38 gestational weeks in 51 pregnant women in whom the fetal kidneys were normal and in 10 whose fetuses had renal pathology (three with suspected nephropathy, three with renal tract dilatation, one with unilateral renal venous thrombosis, and three with twin-twin transfusion syndrome (TTTS)). The ADC was measured in an approximately 1-cm2 region of interest within the renal parenchyma.

RESULTS

ADC values in normal renal parenchyma ranged from 1.1 to 1.8 10(-3) mm2 s-1. There was no significant age-dependent change in the ADC of normal kidneys. In cases of nephropathy, the ADC value was not always pathological but an ADC map could show abnormal findings. In cases of dilatation, the ADC value was difficult to determine when the dilatation was huge. In cases of TTTS, the ADC of the donor twin was higher than that of the recipient twin and the difference seemed to be related to the severity of the syndrome.

CONCLUSION

Evaluation of the ADC for fetal kidneys is feasible. Fetal measurement of the ADC value and ADC maps may be useful tools with which to explore the fetal kidney when used in conjunction with current methods. DW-MR images, ADC value and ADC map seem to be useful in cases of suspected nephropathy (hyperechoic kidneys), dilated kidney and vascular pathology (renal venous thrombosis, TTTS).

Fiabilité de la détermination de l’âge osseux par la méthode de Sauvegrain et Nahum

PURPOSE

The Sauvegrain and Nahum method can be used to assess bone age in addition to methods based on hand and wrist radiographs in children between 9 and 15 years of age. The aim of this study was to evaluate the reliability of this method in a contemporary population.

MATERIAL AND METHODS

Elbow radiographs taken for acute trauma in 106 patients (42 girls, 64 boys) aged from 9 to 15 years old were analyzed by four radiologists. Inclusion in the study required the absence of chronic disease and previous trauma as well as parental consent.

RESULTS

There was no significant difference between the four observers. The differences between bone age (BA) and chronological age (CA) were 5+/-1 months for the study group, 3.5+/-9 months for the female group, and 6+/-12 months for the male group. Bone age was overestimated compared with chronological age. There was a good correlation between CA and BA (r = 0.84).

CONCLUSION

The Sauvegrain and Nahum method seems to overestimate CA in a contemporary population.