Imaging of pediatric bone tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper

Malignant primary bone tumors are uncommon in the pediatric population, accounting for 3%-5% of all pediatric malignancies. Osteosarcoma and Ewing sarcoma comprise 90% of malignant primary bone tumors in children and adolescents. This paper provides consensus-based recommendations for imaging in children with osteosarcoma and Ewing sarcoma at diagnosis, during therapy, and after therapy.

Assessing vascular effects of adding bevacizumab to neoadjuvant chemotherapy in osteosarcoma using DCE-MRI

BACKGROUND

The purpose of this study was to assess the impact of bevacizumab alone and in combination with cytotoxic therapy on tumour vasculature in osteosarcoma (OS) using DCE-MRI.

METHODS

Six DCE-MRI and three (18)F-FDG PET examinations were scheduled in 42 subjects with newly diagnosed OS to monitor the response to antiangiogenic therapy alone and in combination with cytotoxic therapy before definitive surgery (week 10). Serial DCE-MRI parameters (K(trans), v(p), and v(e)) were examined for correlation with FDG-PET (SUV(max)) and association with drug exposure, and evaluated with clinical outcome.

RESULTS

K(trans) (P=0.041) and v(p) (P=0.001) significantly dropped from baseline at 24 h after the first dose of bevacizumab alone, but returned to baseline by 72 h. Greater exposure to bevacizumab was correlated with larger decreases in v(p) at day 5 (P=0.04) and week 10 (P=0.02). A lower K(trans) at week 10 was associated with greater percent necrosis (P=0.024) and longer event-free survival (P=0.034).

CONCLUSIONS

This is the first study to demonstrate significant changes of the plasma volume fraction and vascular leakage in OS with bevacizumab alone. The combination of demonstrated associations between drug exposure and imaging metrics, and imaging metrics and patient survival during neoadjuvant therapy, provides a compelling rationale for larger studies using DCE-MRI to assess vascular effects of therapy in OS.

Bilateral internal hemipelvectomy for osteosarcoma in a pediatric patient previously treated for rhabdomyosarcoma

The surgical treatment of malignant bone tumors involving the pelvis represents a great challenge in terms of local control. Internal hemipelvectomy is a major surgical procedure that involves the resection of the entire hemipelvis or of a portion of the hemipelvis with preservation of the ipsilateral extremity. The need for a bilateral internal hemipelvectomy is an extraordinary situation. We describe the case of an 11-year-old girl with a primary diagnosis of rhabdomyosarcoma of the bladder at the age of two years who subsequently developed a right pelvis osteosarcoma at the age of six years and a left pelvis osteosarcoma at the age of nine years. She ultimately underwent sequential bilateral internal hemipelvectomies and she postoperatively ambulates without an assist device.

Imaging neuroblastoma: what the radiologist needs to know

Neuroblastoma is the most common extracranial solid malignancy in children. The tumor has variable biological behavior that can be predicted by patient age, genetic features, tumor biology and extent of disease at diagnosis. Factors chosen by various cooperative groups to define risk of treatment failure have been non-uniform. Therefore, historically, it has been difficult to compare outcomes across clinical trials performed around the world. This has hindered the advancement of treatment strategies to improve survival of these patients. The International Neuroblastoma Risk Group (INRG) was established in 2004 to develop a consensus approach to pretreatment risk stratification. The result was the development of the INRG Staging System (INRGSS) which relies on imaging-defined risk factors (IDRFs) that are determined before surgery or other therapy. With the application of the INRGSS the radiologist's role in staging children with neuroblastoma is increased. This review provides an overview of the INRGSS and the IDRFs.

Malignant pulmonary and mediastinal tumors in children: differential diagnoses

Conventional chest radiography is the most common imaging procedure in children. When a chest mass is discovered, cross-sectional imaging is often required to accurately localize and characterize the lesion in order to narrow the differential diagnosis. Knowledge of the differential diagnostic possibilities for chest tumors in children is important for both the pediatric and general radiologist because they differ from adults. The more common pediatric, malignant, mediastinal and pulmonary tumors and the characteristic imaging and clinical features that are useful in distinguishing between them are discussed in this review.

Sonographic appearance of appendicitis in a neutropenic pediatric patient after inversion appendectomy

The technique of inversion-ligation appendectomy is used by some surgeons to eliminate the risk of peritoneal contamination as the result of incidental appendectomy during an otherwise clean surgical procedure. In most cases, the intussuscepted appendix necroses and sloughs into the cecum after several days. We present the first report of the ultrasonographic appearance of a retained, inflamed appendix, which occurred in a neutropenic pediatric patient 15 months after inversion appendectomy. Our case illustrates the importance of a complete surgical history for the interpretation of abnormal sonographic findings of the cecum.

Secondary ovarian neoplasms in children: imaging features with histopathologic correlation

BACKGROUND

Although the pathologic features and imaging appearance of childhood primary ovarian neoplasms have been well described, little information is available about the malignancies that may secondarily involve the ovary.

OBJECTIVE

To determine the relationship between the imaging features and the histopathology of secondary ovarian neoplasms in children treated at our institution.

MATERIALS AND METHODS

We searched our institutional database for codes indicating metastatic ovarian disease. Of the 35 patients with such codes, 18 had pathologically proven secondary ovarian disease. From their medical records we recorded demographic data, presenting symptoms, and evidence of endocrine dysfunction. We reviewed the pre-oophorectomy imaging and the subsequent pathologic specimens.

RESULTS

One-third of the patients had bilateral pelvic masses; another third had large masses indistinguishable from the ovaries. Twelve (67%) had either ascites, peritoneal implants, matted bowel, adenopathy, pleural effusions, or some combination of these. Five (28%) had other metastatic disease. Primary tumors included colon adenocarcinoma (9), Burkitt's lymphoma (3), alveolar rhabdomyosarcoma (3), Wilms' tumor (1), neuroblastoma (1), and retinoblastoma (1).

CONCLUSION

Although rare, secondary ovarian tumors should be considered in the differential diagnosis of children with ovarian masses. Bilateral ovarian masses or large masses indistinguishable from the ovaries, particularly in the presence of other metastatic foci, may help distinguish primary from secondary ovarian malignancies.

Prognostic factors and imaging patterns of recurrent pulmonary nodules after thoracotomy in children with osteosarcoma

BACKGROUND

In children with osteosarcoma who have undergone thoracotomy, it often is difficult to distinguish metastatic from benign recurrent pulmonary nodules. The authors of this study sought to identify any computed tomography (CT) imaging pattern of recurrent pulmonary metastases in this patient population. The authors also sought to identify associated prognostic factors.

METHODS

CT scans obtained after thoracotomy were available for 35 patients with osteosarcoma who had undergone resection of presumed pulmonary metastases at St. Jude Children's Research Hospital (Memphis, TN). CT scans obtained before the initial thoracotomy were available for 33 of the 35. The authors recorded location, histologic diagnosis, and time of development of the original pulmonary nodules, time of recurrence of pulmonary disease; the location of recurrent nodules, and the presence of calcification, adenopathy, or progressive pleural disease, as well as patient demographic data, survival data, and location of the primary tumor site.

RESULTS

Pulmonary nodules recurred in 32 of the 35 patients after thoracotomy. Nineteen of these patients underwent resection of the recurrent lesions and 1 who died underwent an autopsy; 18 of the 20 patients had metastatic disease. The only CT finding consistently associated with recurrent metastatic disease was progressive pleural thickening, which predicted a poor outcome. The occurrence of a solitary pulmonary nodule in the lung contralateral to the previous surgery was associated almost always with a benign process.

CONCLUSIONS

CT imaging cannot distinguish reliably between benign and metastatic recurrent pulmonary disease after thoracotomy in patients with osteosarcoma. Recurrent pulmonary disease in this set of patients is likely to be metastatic, and aggressive surgical intervention is probably warranted. In this study, patients who had progressive pleural disease after thoracotomy consistently experienced pulmonary metastatic recurrence and had a poor prognosis.

Hepatic veno-occlusive disease in children undergoing bone-marrow transplantation: usefulness of sonographic findings

BACKGROUND

Reports of the usefulness of ultrasonography in the diagnosis of hepatic veno-occlusive disease (HVOD) have presented conflicting results.

OBJECTIVE

To determine the usefulness of gray-scale or Doppler ultrasonographic measurements in the diagnosis of HVOD in pediatric patients undergoing BMT.

MATERIALS AND METHODS

We prospectively obtained 202 serial sonograms on 48 patients and examined the association between the clinical diagnosis of HVOD (McDonald criteria) and eight ultrasound parameters, including the hepatic artery resistive index (HARI), direction and velocity of portal venous flow, and thickness of the gall bladder wall.

RESULTS

HVOD developed in 29 of the 48 patients. The portal venous velocity increased after BMT in the group without HVOD and decreased in the group with HVOD; this difference was significant (P = 0.01). However, there was a great deal of variability in velocity measurements for individual patients. The mean HARI was 0.64 in the group with HVOD and 0.63 in the group without HVOD, and there was no difference between the two groups in the pattern of change in HARI relative to the day of BMT (P = 0.4). There was also no significant difference in thickness of the gallbladder wall between the two groups (P = 0.6).

CONCLUSION

No ultrasound parameter studied was as useful as the McDonald criteria for diagnosing HVOD.

Selective use of whole-lung irradiation for patients with Ewing sarcoma family tumors and pulmonary metastases at the time of diagnosis

PURPOSE

The benefit of whole-lung irradiation (WLI) for patients who have pulmonary metastases (PM) of Ewing sarcoma family tumors (ESFT) is unclear. At our institution, WLI is reserved for patients with PM that do not respond completely to induction chemotherapy. We reviewed our experience to assess the impact of WLI on clinical outcome.

PATIENTS AND METHODS

Twenty-eight patients with ESFT and PM were treated in three consecutive institutional trials (1979-1996). Extent of pulmonary involvement at diagnosis, response of PM after induction chemotherapy, local treatment of PM thereafter, and clinical outcome were recorded. Treatment included primary tumor surgery and/or radiotherapy and 42 to 58 weeks of multiagent chemotherapy.

RESULTS

Only eight patients (29%) received WLI. For the entire study group, the estimated 5-year event-free survival was 22.9% +/- 9.0%; the 5-year survival was 37.3% +/- 9.8%. Complete resolution of PM after induction chemotherapy was not correlated with survival (P = 0.53), nor was treatment with WLI (P = 0.87).

CONCLUSIONS

The comparable survival of patients with poor and good response of PM to induction chemotherapy suggests that WLI may benefit poor responders. The use of WLI in good responders may provide similar benefit and merits further study.

Imaging findings of hemorrhagic cystitis in pediatric oncology patients

In pediatric oncology patients, hemorrhagic cystitis may be a life-threatening complication of bone-marrow transplantation, chemotherapy, and/or radiation therapy. The inciting agent in urine can affect the entire urothelium from the renal collecting system to the bladder, and the severity of disease can vary. The radiologist often plays a key role in the diagnosis, follow-up, and occasionally the treatment of hemorrhagic cystitis and its complications. This review discusses the imaging findings in the kidneys and bladder in patients with hemorrhagic cystitis both before and after treatment for this disease. Findings on two-dimensional sonography, color Doppler and power Doppler sonography, computed tomography, magnetic resonance imaging, antegrade pyleography, and cystography are presented.