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.

[Pediatric thoracic spine radiographs: Comparison of two scintillators]

PURPOSE

To compare image quality and radiation exposure from pediatric thoracic spine radiographs from two systems, one using a granular structure scintillator and another using a needle structure scintillator with 40% reduction of exposure.

PATIENTS AND METHODS

Randomized prospective study of 296 patients divided into 2 groups of 5 weight categories from 4 to 60 kg. Standard technique parameters are used for granular structure scintillators with dose reduction of 40% applied for needle structure scintillators based on results from a phantom study. Image quality based on detectability of 8 anatomical structures for both types of scintillators was assessed by 6 blinded radiologists. Exposure was expressed by DLP. Results underwent statistical analysis.

RESULTS

Overall, image quality was superior with corresponding dose reduction between 33-46% according to weight with needle structure scintillators. For the 4 lower weight categories, image quality was identical.

CONCLUSION

With image quality at least equal, new needle structure scintillator units allow a dose reduction of about 40%.

[Percutaneous treatment of cystic lymphangiomas]

Management of cystic lymphangioma necessitate for optimal diagnosis and treatment the expertise of a trained multidisciplinary team including dermatologists, radiologists, plastic and vascular surgeons. An initial imaging work-up of these lesions by ultrasound Doppler examination and MR imaging are necessary before treatment planning. Depending of the size, the location, the risk for the adjacent organs, a therapeutic decision may be mandatory. Percutaneous sclerotherapy is a safe and efficient treatment. It is the treatment of choice that must be proposed in first intention.

Localized cervical neuroblastoma: prevention of surgical complications

OBJECTIVES

The purpose of this study focused on cervical neuroblastoma (NB) was to assess the prognosis, define the most suitable methods of investigation, and evaluate risk factors for complications following primary surgery.

METHODS

Between 1990 and 1999, we conducted two consecutive prospective multicentric studies (NBL90 and NBL94) on localized NB. Because the first study (1990-1994) found surgery-related morbidity and mortality, several surgical risk factors (i.e. adhesion to major vessels, size, friability, and dumb bell tumor) were defined and used prospectively as criteria of resectability in the second study (1994-1999).

RESULTS

Of 617 cases included in the two studies, 43 involved cervical NB including 17 cervicothoracic tumors. With a median follow-up of 4 years, overall survival and event-free survival rates were 91 and 81%, respectively with no significant difference between cervical or cervicothoracic NB. Seventeen patients were included in the second study; surgery was used as the first line treatment in 11. Full pre-operative work-up was performed in eight patients, demonstrating one or more risk factors in three. The remaining three patients underwent emergency surgery with no pre-operative work-up or only ultrasound: two developed serious complications. All three patients presenting documented risk factors developed post-operative complications versus only two of the eight patients who presented no risk factor (n = 5) or were inadequately evaluated (n = 3) (P = 0.06). None of the five patients in whom full work-up demonstrated no risk factor had post-operative complications (P = 0.02).

CONCLUSIONS

Cervical neuroblastoma has a favorable prognosis. Surgery is the treatment of choice but there is a risk of complications. Appropriate pre-operative work-up is mandatory to evaluate resectability. The surgical risk factors defined for our second study seem to be significant predictors of post-operative complications.

Kyste du cholédoque avec dilatation congénitale du canal cystique : à propos de deux cas

We report two cases of a choledochal cyst associated with dilatation of the cystic duct. This unusual variant of choledochal cyst was explored by ultrasonography and MR cholangiopancreatography.

[Lipoblastoma of the buttock]

Lipoblastoma is an uncommon benign soft tissue tumor arising from embryonal mesenchymal cells. It occurs mostly during early childhood with a predilection for the extremities, trunk, head and neck. This tumor tends to spread locally and no metastatic potential has been reported. Complete surgical resection is mandatory to prevent local recurrence. MRI provides excellent presurgical delineation of the tumor and confirms its fatty nature. Histology demonstrates the presence of lipoblasts in different stages of maturation; cytogenetic evaluation often discloses chromosomal anomalies of tumoral cells. A case of lipoblastoma of the buttock in a 10 month infant associated with anomalies of chromosome 8 is reported.

Microcephalic osteodysplastic primordial dwarfism Taybi-Linder type: report of four cases and review of the literature

Microcephalic and osteodysplastic primordial dwarfism (MODP) types I, II, and III were defined by Majewski et al. in 1982. This group of syndromes was characterized by intrauterine growth retardation, microcephaly, and typical facial appearance with prominent nose and micrognathia. Type II was clearly different, both clinically and radiologically, whereas types I and III shared manifestations. Distinction between the latter two was established on the basis of subtle radiological differences. In 1967, Taybi and Linder described another syndrome with microcephalic congenital dwarfism. There is a consensus that MODP type I and III and Taybi-Linder cephaloskeletal dysplasia represent the same disorder. We report on four patients with MODP type Taybi-Linder syndromes, two of whom were born to unrelated but consanguineous parents, while the other two were sibs. Second-trimester prenatal detection by ultrasonography was possible in one case. Consanguinity in two cases and recurrence among sibs are consistent with autosomal recessive inheritance.

Congenital bowing of the long bones in two fetuses presenting features of Stüve-Wiedemann syndrome and Schwartz-Jampel syndrome type 2

We report two fetuses with congenital bowing of the long bones. Clinical and radiological features led us to consider two conditions: the Stüve-Wiedemann syndrome and the neonatal Schwartz-Jampel syndrome type 2. Similarities between the two syndromes are discussed.

Imaging of vascularized fibular grafts in large bone reconstruction in skeletally immature patients

OBJECTIVE

To describe the imaging findings of vascularized fibular grafts (VFG) in large bone reconstruction in children and teenagers.

DESIGN AND PATIENTS

Fifteen patients aged from 4 to 19 years underwent VFG for bone reconstruction for primary tumors involving bone in 13 cases and for chronic osteomyelitis in 2 cases. Lesions were located in the femur (6 cases), the tibia (6 cases), the humerus, the distal fibula and the ilium. Radiographic follow-up was performed in all patients, radionuclide studies in 12 patients and MRI in 8.

RESULTS

Plain films showed a lamellated periosteal reaction on the VFG within 3 weeks following the procedure in all cases. Fusion of VFG and host bone occurred during the first 3 months. Radionuclide uptake of the VFG was seen in all cases but one. MRI showed cortical thickening and conservation of the high signal intensity of fatty marrow on T1-weighted sequences, and periosteal enhancement on dynamic post-contrast studies in all but one of the patients.

CONCLUSION

Radionuclide studies and MRI show the periosteal enhancement and assess the viability of the VFG satisfactorily. However, we feel that plain films may be sufficient to ascertain this viability.