Search

OBJECTIVE. Distinguishing nephrogenic rests from small Wilms tumors can be challenging. This retrospective study was performed to determine if imaging characteristics can be used to distinguish nephrogenic rests from Wilms tumors. MATERIALS AND METHODS. All cases of pathologically confirmed nephrogenic rests and Wilms tumors smaller than 5 cm in maximum dimension on imaging in patients younger than 5 years old were identified from the Children’s Oncology Group AREN03B2 study (July 2006–August 2016). Exclusion criteria were chemotherapy before pathologic evaluation or more than 30 days between imaging and surgery; in addition, patients with nephrogenic rests occurring within or juxtaposed to a Wilms tumor and patients with diffuse hyperplastic perilobar nephroblastomatosis were excluded. Two radiologists who were blinded to pathology results assessed all lesions. The two-sample t test was used for continuous variables, and the Fisher exact test was used for categoric variables. ROC analysis was performed to determine the optimal size cutoff for distinguishing between nephrogenic rests and Wilms tumors. RESULTS. Thirty-one pathologically confirmed rests (20 perilobar, 11 intralobar) and 26 Wilms tumors smaller than 5 cm met the eligibility criteria for study inclusion. The median diameter of the nephrogenic rests was 1.3 cm (range, 0.7–3.4 cm) and the median diameter of the Wilms tumor was 3.2 cm (range, 1.8–4.9 cm) (p < 0.001). Imaging findings supportive of Wilms tumors were spherical (p < 0.001) and exophytic (p < 0.001) lesions. Perilobar rests (17/20) were more likely to be homogeneous than intralobar rests (3/11) or Wilms tumor (3/26) (p < 0.001). ROC analysis showed that the optimal size cutoff for distinguishing between nephrogenic rests and Wilms tumors was 1.75 cm. CONCLUSION. In children younger than 5 years old, the diagnosis of a Wilms tumor should be favored over a nephrogenic rest when a renal mass is spherical, exophytic, or larger than 1.75 cm. Homogeneity favors the diagnosis of perilobar nephrogenic rests, whereas intralobar rests and Wilms tumors are more likely to be inhomogeneous.

Wilms tumor is the most common pediatric renal tumor, accounting for approximately 7% of all childhood cancers. Imaging plays an important role in the detection, staging, post-therapy evaluation and surveillance of Wilms tumor. Wilms tumor can be detected during surveillance of a known cancer predisposition or after a child presents with symptoms. In this manuscript we describe an evidence-based approach to the initial evaluation of Wilms tumor using current guidelines from the Children's Oncology Group (COG). We illustrate the COG staging system for pediatric renal tumors and highlight key imaging findings that are critical for surgical management. We also discuss the controversies regarding detection and significance of

To retrospectively determine the diagnostic performance of computed tomography (CT) in identifying the presence or absence of preoperative Wilms tumor rupture.The cohort was derived from the AREN03B2 study of the Children's Oncology Group. The study was approved by the institutional review board and was compliant with HIPAA. Written informed consent was obtained before enrollment. The diagnosis of Wilms tumor rupture was established by central review of notes from surgery and/or pathologic examination. Seventy Wilms tumor cases with rupture were matched to 70 Wilms tumor controls without rupture according to age and tumor weight (within 6 months and 50 g, respectively). CT scans were independently reviewed by two radiologists, and the following CT findings were assessed: poorly circumscribed mass, perinephric fat stranding, peritumoral fat planes obscured, retroperitoneal fluid (subcapsular vs extracapsular), ascites beyond the cul-de-sac, peritoneal implants, ipsilateral pleural effusion, and intratumoral hemorrhage. All fluids were classified as hemorrhagic or nonhemorrhagic by using a cutoff of 30 HU. The relationship between CT findings and rupture was assessed with logistic regression models.The sensitivity and specificity for detecting Wilms tumor rupture were 54% (36 of 67 cases) and 88% (61 of 69 cases), respectively, for reviewer 1 and 70% (47 of 67 cases) and 88% (61 of 69 cases), respectively, for reviewer 2. Interobserver agreement was substantial (ĸ = 0.76). All imaging signs tested, except peritoneal implants, intratumoral hemorrhage, and subcapsular fluid, showed a significant association with rupture (P ≤ .02). The attenuation of ascitic fluid did not have a significant correlation with rupture (P = .9990). Ascites beyond the cul-de-sac was the single best indicator of rupture for both reviewers, followed by perinephric fat stranding and retroperitoneal fluid for reviewers 1 and 2, respectively (P.01).CT has moderate specificity but relatively low sensitivity in the detection of preoperative Wilms tumor rupture. Ascites beyond the cul-de-sac, irrespective of attenuation, is most predictive of rupture.

Little information exists regarding pediatric contrast-enhanced US. To assess the safety and feasibility of contrast-enhanced US of pediatric abdominal and pelvic tumors. This prospective study included eight boys and five girls (mean age, 10.8 years) with abdominal or pelvic tumors. Cohorts of three subjects underwent US with perflutren contrast agent at escalating dose levels. Neurological and funduscopic examination, electrocardiography and continuous pulse oximetry were performed before and after contrast administration. Three radiologists independently scored six imaging parameters on pre- and postcontrast sonography. Inter-reviewer agreement was measured by the Kappa statistic. No neurological, retinal, electrocardiographical or pulse oximetry changes were attributable to the contrast agent. Two subjects reported minor, transient symptoms. Postcontrast US parameter scores improved slightly in 8 of 12 subjects. Postcontrast ultrasound inter-reviewer agreement improved slightly for detection of tumor margins (precontrast = 0.20, postcontrast = 0.26), local tumor invasion (precontrast = -0.01, postcontrast = 0.10) and adenopathy (precontrast = 0.35, postcontrast = 0.44). Although our sample size is small, perflutren contrast agents appear to be safe and well tolerated in children. Contrast-enhanced sonography of pediatric abdominal and pelvic tumors is feasible, but larger studies are needed to define their safety and efficacy in children.

The outcome of desmoid tumor in children cannot be reliably predicted on the basis of histologic findings. We sought to determine whether the postoperative presence of residual or recurrent tumor can be predicted on the basis of demographic variables and baseline MRI features of the tumor. We also aimed to determine how imaging features change during adjuvant treatment and how the imaging features relate to the histologic features.Two radiologists retrospectively reviewed images from 281 MRI examinations performed at baseline and during postoperative therapy for desmoid tumor. The examinations had been performed on 17 children treated between September 1991 and March 2003. Tumor volume; distinctness of margins; involvement of bone and neurovascular bundle; and T1-weighted, T2-weighted, and STIR signal intensity and contrast enhancement pattern were recorded. Baseline imaging and demographic features were correlated with the postoperative presence of residual or recurrent tumor. Imaging changes during follow-up were compared with treatment response and outcome. The imaging features of eight tumors were compared with percentage cellularity and collagen deposition in biopsy samples obtained within 30 days of imaging.Baseline involvement of the neurovascular bundle approached significance as a predictor of the presence of residual or recurrent tumor (p = 0.08). Other baseline imaging and demographic features were not predictive (por = 0.4). Changes in imaging features were variable during follow-up. T2-weighted and STIR signal intensity may be correlated with percentage cellularity and collagen deposition.MRI has limited value in prediction of the postoperative presence of residual or recurrent desmoid tumor in children. It is useful, however, for detecting disease and monitoring postoperative adjuvant therapy.

Core body temperature elevation (hyperthermia) can occur during radiofrequency ablation of large centrally located tumors in small children. Hyperthermia can be predicted on the basis of long burn times, high wattage delivered by the RF system and low body weight. If hyperthermia is anticipated, cooling blankets using refrigerated air or water are recommended. The advantage of these systems is that the cooling can help maintain normal core body temperature.

Pleurodesis for end-of-life care has been used in adults for decades, but little is known about the usefulness of this technique in improving the quality of care for pediatric patients.To assess whether intractable pleural effusions in pediatric oncology patients at end of life could be sufficiently relieved by pleurodesis.Eleven pleurodeses were performed with doxycycline in seven pediatric cancer patients (age 3-21 years) with intractable pleural effusions at the end of life. Five patients had unilateral pleurodeses and two had a unilateral followed by bilateral pleurodeses.Respiratory rates decreased in all seven patients (P = 0.016) and aeration improved significantly after chest tube placement (P = 0.033). The chest tubes were placed a median of 1 day before pleurodesis. Eight of nine chest tubes (89%) were removed before discharge at a median of 3 days after pleurodesis. Pain secondary to the pleurodesis lasted 1 day or less. Improvement in the respiratory rate remained after pleurodesis and chest tube removal (P = 0.031). Five of seven patients (70%) were able to leave the hospital to return home. The five patients discharged lived 10 to 49 days (median 19 days) after discharge.Pediatric oncology patients with intractable effusions at end of life can have respiratory benefit from pleurodeses and, as a result, are more likely to return home for terminal care.

Background: MRI is an effective tool in evaluating bone marrow metastases. However, no study has defined which MRI sequences or image characteristics best correlate with bone-marrow metastases in neuroblastoma. Objective: To identify and refine MRI criteria and sequence selection for the diagnosis of bone-marrow metastases in children with neuroblastoma. Materials and methods: Ninety-one children (mean age: 3.2 years; standard deviation: 2.8 years) enrolled in the RDOG IV study participated in our study. Forty-five children had bone metastases determined by bone-marrow aspiration or biopsy (n=4), radionuclide imaging (n=2), or both (n=39). Spine lesions were characterized using coronal T1-weighted (T1W) sagittal short tau inversion recovery (STIR) and coronal gadolinium-enhanced T1-weighted (GAD) MR sequences. Contingency table analysis was performed to determine which MRI sequences and characteristics were associated with metastases. The MRI criteria for metastatic disease were then developed for each imaging sequence. The sensitivity, specificity, predictive values, and accuracy of these criteria were determined for the whole group, children younger than 12 months old, and children 12 months and older. Results: The MR characteristics that had significant (P ≤ 0.05) associations with metastases were homogeneous low T1-signal intensity, homogeneous high STIR-signal intensity, and heterogeneous pattern on T1, STIR, or GAD. Homogeneous low T1-signal had the highest sensitivity (88%), but a specificity of 62% for detecting metastases. A heterogeneous pattern on GAD was highly specific (97%), but relatively insensitive (65%) for detecting metastases. These MR characteristics were most accurate in children 12 months and older. Conclusion: The combination of non-contrast-enhanced T1W and GAD sequences can be used to determine the presence of spinal metastases in children with neuroblastoma, particularly those children who are 1 year and older.

Fluid aspiration, percutaneous biopsy, and catheter drainage are standard minimally invasive methods of diagnosing lymphoma or leukemia in adults.To determine the effectiveness of interventional radiologic techniques in diagnosing specific hematologic malignancies in children.During a 4-year period, 22 patients (16 male, 6 female; median age, 13 years) underwent 25 percutaneous biopsies, 6 fluid aspirations, 3 catheter drainages, and 1 needle localization for diagnosing suspected hematologic malignancy.For Hodgkin's disease, the procedures yielded 6 true-positive (TP) results, 2 true-negative (TN) results, and 2 false-negative (FN) results; for non-Hodgkin lymphoma (NHL), 14 TP results, 1 TN result, and 3 FN results; and for leukemia, 4 TP results and 3 FN results. Percutaneous biopsies yielded 16 TP results, 3 TN results, and 6 FN results. Aspirations and drainages yielded 8 TP results and 1 FN result. The one needle localization yielded a FN result. Overall sensitivity was 75%+/-7.3%; specificity, 100%; and accuracy, 77%+/-7.1%.Percutaneous biopsy of lymphoma is usually diagnostic. Drainage or aspiration of a fluid collection associated with NHL or leukemia is often diagnostic and is less invasive than biopsy. These procedures are minimally invasive and effective for diagnosing pediatric hematologic malignancies.

Background. The identification of risk factors that predict poor clinical outcome at the time of diagnosis could lead to intensified early therapy and improved outcome for pediatric patients with Ewing sarcoma family of tumors (ESFT). Objective. To compare the effectiveness of static magnetic resonance (MR) imaging measurements of tumor volume with variables obtained by dynamic contrast-enhanced MR imaging (DEMRI) in predicting ESFT outcome. Methods. MR examinations that included DEMRI were retrospectively reviewed. The analyses included 45 examinations of 21 patients with ESFT (performed from 1992 to 1996). Tumor volumes were measured on the static MR images, and the regions of interest were selected for DEMRI analysis. The relationships of static MR imaging and DEMRI variables with the probability of progression-free survival (PFS) and disease-free survival (DFS) were determined. Results. Larger tumor volume at the time of diagnosis predicted poorer PFS and DFS estimates. No DEMRI variable predicted outcome. Conclusion. Determination of tumor volume by static MR imaging at the time of diagnosis is a simple and reliable method of predicting the clinical outcome of patients with ESFT. DEMRI is not as reliable a technique as static MR imaging for predicting the outcome of these patients.

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.

Malignant mesothelioma is a rare tumor in childhood. We present two cases of malignant peritoneal mesothelioma in which contrast-enhanced, fat-saturated magnetic resonance (MR) imaging was used advantageously to detect peritoneal tumor involvement.

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.

We used contrast-enhanced three-dimensional magnetic resonance angiography (3D MRA) modified for pediatric use to evaluate the hepatic vasculature prior to partial hepatectomy in five consecutive children with hepatoblastoma. Modifications included non-breath-hold technique in four of the five children who were sedated. The single breath-hold technique was performed in only one awake child. Scan delay times were based on contrast infusion time rather than total infusion time. The hepatic artery, portal vein, and inferior vena cava were identified in all patients. MRA findings were confirmed by conventional angiography in one patient and by surgery in all. Contrast-enhanced 3D MRA is a useful and rapid technique prior to partial hepatectomy in patients with hepatoblastoma.

This paper reviews the techniques that we employ to perform musculoskeletal magnetic resonance imaging in the pediatric patient. We examine the procedures for preparation and screening of the patient and the protocols for sedation. The selection of imaging coils and sequences for the evaluation of the pediatric musculoskeletal system is also addressed, followed by a summary of scanning protocols.

Localization of skeletal tracer in a neuroblastoma primary is common but localization in extraskeletal metastatic sites has not received recognition. Tc-99m MDP concentration in hepatic or pulmonary metastases was noted in three of ten patients with such metastases. Lesion size appears to be important for demonstrating these metastases with Tc-99m MDP. This was particularly true for hepatic metastases, which were identified only when they were 5 cm or greater in diameter.

PURPOSE: To determine whether percutaneous biopsy can provide the diagnostic and prognostic information necessary to treat children with advanced neuroblastoma. MATERIALS AND METHODS: From 1991 through 1995, 21 percutaneous biopsies were performed in 20 children with advanced neuroblastoma by using 15- or 16-gauge core biopsy needles. An average of six samples were obtained. Since September 1994, fresh tissue was sent to the reference laboratory, where touch preparations were prepared for N-myc evaluation. RESULTS: Histologic confirmation and prognostic information (Shimada classification) were obtained in all cases. Genetic prognostic information was obtained in 19 patients (95%), DNA index (ploidy) in 18 (90%), N-myc gene expression in 14 (70%), and cytogenetic analysis in 10 (50%). N-myc and ploidy determinations were successful in all five biopsy specimens obtained since September 1994. CONCLUSION: Percutaneous biopsy of advanced neuroblastoma is a feasible alternative to open biopsy.

Interventional radiology techniques to treat oncological disease have already shown value in adults. The adoption and development of interventional oncology (IO) in children have been more limited and challenging. This relates to the approval process for new devices and agents, oncology group protocol limitations and the inherent hesitation of trying new treatments in children. This paper will discuss how new procedures are developed and approved, and the new therapies that will become available to better treat pediatric malignancies. Bringing the benefits of IO to children will require initiative on the part of pediatric diagnostic and interventional radiologists as well as the cooperation of our clinical colleagues.

Interventional radiologists (IRs) with expertise in image guidance have an inherent skill set for the safe and reliable placement of central venous access catheters (CVACs) in children. Above and beyond the technical requirements, IRs have an integral role as consultants in evaluating children for the most appropriate catheter to meet their short- and long-term needs. This article is meant to serve as a reference for decision making along with tips and pearls on how we approach placing CVACs in pediatric patients at our Children's Hospital.

Image-guided procedures involving the musculoskeletal (MSK) system of children can be challenging because of the variability posed by the child's age, skeletal maturity, and the stage of development. The imaging findings of the maturing MSK system and the underlying diseases affecting children, particularly those that are skeletally immature, can differ significantly from typical adults. The breadth of possible MSK procedures performed by an interventional radiology service depends on the availability of local expertise/experience as well as the referral patterns. In our practice, the majority of nonvascular MSK procedures involve children with a sequela of pain and in need of a therapeutic intervention. We describe our techniques for our more commonly performed MSK procedures, including corticosteroid injections, treating osteoid osteomas, and performance of image-guided bone biopsies and foreign body removal.

We report an unusual case of a child with a congenital solitary functional kidney complicated by a sports-related posttraumatic Page kidney. The child developed severe hypertension and renal insufficiency requiring percutaneous intervention to preserve renal function. The literature is sparse with no definitive guidelines for the treatment of Page kidney. Following the initial unsuccessful treatment with percutaneous drainage and sclerotherapy procedures, the child ultimately required catheter-directed particle embolization of the capsular arteries to resolve a recurrent subscapsular hematoma definitively. This was successful in preserving renal function and stabilization of the clinical manifestations of the Page kidney.

A recently developed rf echo planar imaging method has been modified to rapidly generate spectroscopic information along one in-plane axis and spatial information along the other. The method allows the production of one-dimensional chemical shift images (1D CSIs) in acquisition times of 18 sec or less. A specific phase-encode-reordering algorithm provides convenient manipulation of T2 weighting, yielding partial suppression of short T2 species like muscle water. The method is demonstrated in phantoms and in vivo with 1D CSIs of human brain and limbs. Abnormal fat distribution is demonstrated in the calf of a patient with aggressive fibromatosis. The advantages of short acquisition times obtainable with SIRFEN are offset by limited spectral resolution, suggesting that primary applications will be confined to rapid spatial mapping of major spectral components.

We present a unique case of Budd-Chiari syndrome caused by Gaucher's disease. The diagnosis was based on Doppler sonography, magnetic resonance imaging, contrast-enhanced three-dimensional magnetic resonance angiography, standard venography, and venous pressure measurements and was confirmed histologically.

Purpose. We report a case of Ewing's sarcoma in the right distal femur in a 6-year-old male to demonstrate how dynamic contrast-enhanced magnetic resonance imaging (DEMRI) findings predicted histopathology. Materials and methods. DEMRI was performed at presentation and during and after completion of chemotherapy and radiation therapy. Histopathologic studies were done at presentation, at 77 weeks (20 weeks after a pathological fracture), and from the en bloc resection at 104 weeks. Results. DEMRI predicted the early tumor response, absence of tumor recurrence, presence of necrosis and lack of fracture healing, confirmed by histopathology. Conclusion. DEMRI is a clinically useful tool in managing Ewing's sarcoma.

Purpose/Objective This study aimed to develop objective models of radiation effects on musculature in children with soft tissue sarcoma using treatment dosimetry and clinical and quantitative magnetic resonance imaging (MRI) parameters that may be used to guide treatment planning or predict side effects. Methods In the initial 13 patients undergoing external beam radiation therapy (RT) on a Phase II study of conformal or intensity-modulated RT for the treatment of soft tissue sarcoma approved by an Institutional Review Board, we evaluated quantitative MRI changes in the musculature to assess radiation-related treatment effects. Patients with soft tissue sarcoma, including Ewing's sarcoma, had quantitative T 1 , T 2 and dynamic enhanced MRI (DEMRI) performed before, during (Week 4) and after RT (Week 12). Regions of interest were selected in consistent locations within and outside the high-dose regions (on ipsilateral and contralateral sides when available). Mean RT dose, T 1 , T 2 and DEMRI parameters were calculated and modeled using a mixed random coefficient dose model. Results The mean doses to the high- and low-dose regions were 56.4 Gy (41.8–75.3 Gy) and 13.0 Gy (0.1–37.5 Gy), respectively. Compared with tissues distant from the tumor bed, maximal enhancement was significantly increased in tissues adjacent to the tumor/tumor bed prior to RT (60.6 vs. 44.2, P =.045) and remained elevated after 12 weeks. T 1 was significantly elevated in tissues adjacent to the tumor bed prior to RT (942.4 vs. 759.0, P =.0078). The slope of longitudinal change in T 1 was greater for tissues that received low-dose irradiation than those that received high-dose irradiation ( P =.0488). The effect of dose on the slope of T 2 was different ( P =.0333) when younger and older patients are compared. Conclusions Acute affects of irradiation in muscle are quantifiable via MRI. These models provide evidence that quantifiable MRI parameters may be correlated with patient parameters of radiation dose and clinical factors including patient age. Long-term follow-up will be required to determine if acute changes correlate with clinically significant late effects.

Magnetic resonance (MR) plays a unique role in the diagnosis and management of pediatric abdominal masses. The “as low as reasonably achievable” (ALARA) radiation dose of CT is zero when substituted by MR. Whole body MR may also compete with PET imaging to stage abdominal tumors. Specific advantages of MR include determination of resectability of hepatic tumors using MRI and MRA; staging of neuroblastoma in the bone marrow, lymph nodes, liver, and spinal canal; response of bilateral Wilms tumor and nephroblastomatosis; detection of pelvic tumors with sagittal sectioning, and peritoneal tumors with contrast enhancement.

We present the radiological and clinical aspects of a patient with advanced-stage Burkitt lymphoma who presented with an acute abdomen complicated by abdominal compartment syndrome.

There are many radiological interventions necessary for pediatric oncology patients, some of which may be covered in other articles in this publication. I will discuss a number of interventions including percutaneous biopsy for solid tumor and hematological malignancy diagnosis or recurrence, for the diagnosis of graft versus host disease after stem cell or bone marrow transplantation, and for the diagnosis of complications of immunosuppression such as invasive pulmonary aspergillosis. In the past, tumor localization techniques have been necessary to biopsy or resect small lesions. However improved guidance techniques have allowed for more precise biopsy and the use of thermal ablation instead of excision for local tumor control. A percutaneously placed radio frequency, microwave, laser or cryogen probe can ablate the primary and metastatic tumors of the liver, lung, bone, kidney and other structures in children. This is an alternative treatment for the local control of tumors that may not be amenable to surgery, chemotherapy or radiotherapy. I will also describe how chemoembolization can be used to treat primary or metastatic tumors of the liver that have failed other therapies. This treatment delivers chemotherapy in the hepatic artery infused with emboli to increase the dwell time and concentration of the agents.

Pediatric interventions for oncology patients include aspiration or percutaneous biopsy for malignancy diagnosis or recurrence, and percutaneous biopsy for the complications of tumor treatment. Tumor localization techniques have been used to resect small lesions with minimal invasion. However improved guidance techniques have allowed for more precise biopsy and the use of thermal ablation instead of excision for local tumor control. I will discuss these diagnostic and therapeutic techniques as they apply to children.

Pelvic neoplasms can arise from the genitourinary tract, gonads, soft tissues, or bone. The role of imaging is to confirm the presence of tumor, determine the site of origin, delineate the extent for staging and treatment planning, and serve as a baseline for monitoring response to therapy. MR imaging is well suited for the characterization and staging of pediatric pelvic tumors. This article reviews the imaging findings and staging evaluation of the common nongynecologic neoplasms in children. Prostatic, bladder, gonadal, and sacrococcygeal tumors are discussed. Gynecologic tumors are discussed elsewhere in this issue.

The care for children and adolescents with malignant bone tumors such as osteosarcoma and Ewing sarcoma will be improved by the magnetic resonance imager that can recognize the tumor early in its course and can stage it correctly for proper chemotherapy and local control. This can be accomplished by attention to the proper magnetic resonance imaging technique, recognition of the magnetic resonance appearance, and knowledge of the prognostic factors at diagnosis. Determination of response on follow-up static and dynamic contrast-enhanced magnetic resonance imaging and knowledge of optimal methods to determine recurrent tumor will improve the outcome for these children.

The authors have intentionally included some confusing examples to demonstrate that the imaging findings of benign and malignant pediatric bone lesions are not always pathognomonic. The radiologist's role is to recognize malignant bone lesions and encourage the prompt referral of these patients to an appropriate institution for biopsy and treatment. The radiologist must also be able to identify benign lesions and help determine whether these lesions require biopsy and intervention or simply observation.

Background. Invasive pulmonary aspergillosis is fulminant and often fatal in immunosuppressed patients. Percutaneous biopsy may select patients who could benefit from surgical resection. Objective. We sought to determine the accuracy of percutaneous biopsy for pediatric invasive pulmonary aspergillosis. Materials and methods. We retrospectively reviewed 28 imaging-guided percutaneous biopsies of the lungs of 24 children with suspected pulmonary aspergillosis. Twenty-two were being treated for malignancy and two for congenital immunodeficiency; 15 had received bone-marrow transplants. The accuracy of the percutaneous lung biopsy was determined by subsequent surgical resection, autopsy, or clinical course. Results. Histopathological studies showed ten biopsy specimens with septate hyphae, indicating a mold, and seven with Aspergillus flavus colonies in culture. The remaining 18 biopsies revealed no fungi. No patient had progressive aspergillosis after negative biopsy. Invasive pulmonary mold was detected by percutaneous biopsy with 100 % (10/10) sensitivity and 100 % (18/18) specificity. Percutaneous biopsy results influenced the surgical decision in 86 % (24 of 28) of the cases. Bleeding complicated the biopsy in 46 % (13/28) and hastened one death. Conclusion. Percutaneous biopsy of the lung is an accurate technique for the diagnosis of invasive pulmonary aspergillosis and correctly determines which immunosuppressed pediatric patients would benefit from therapeutic pulmonary resection.

Pediatric oncology patients with large metallic prostheses were imaged with one of two MR imaging techniques: 1) the “tilted view-angle” technique, 2) or a higher readout bandwidth technique. The tilted view-angle method uses an additional gradient in the slice selection direction during readout. The high bandwidth technique increases the readout bandwidth and shortens the echo time (TE). High bandwidth and short echo times were implemented in both T1-weighted (T1W) turbo spin echo and turbo short tau inversion recovery (STIR) sequences. Both imaging techniques reduced the size of metal-induced image artifacts. The tilted view-angle method reduced the artifact to a greater degree but had inherent shortcomings. The reformatted images were blurred and shifted. The area of interest was often moved outside of the field of view, unless parameters were adjusted on the basis of a pre-scan calculation. The high readout bandwidth, short echo technique required no special preparation and reduced metal artifacts without image blurring. The combination of high-bandwidth, shorter echo turbo STIR and T1W turbo spin echo sequences with subtraction of pre- from post-contrast images allowed effective fat suppression without local field inhomogeneity affects. This greatly improved our ability to evaluate suspected disease near metallic implants in pediatric cancer patients.

Background. Survivors of childhood acute lymphocytic leukemia (ALL) are at risk of venous occlusion induced by central venous access devices (CVADs). A sensitive, noninvasive screening technique to identify the magnitude of this problem is needed. Ultrasound (US) cannot always adequately image the innominate veins or the superior vena cava. Magnetic resonance angiography (MRA) can be noninvasive and may be useful for screening these patients. Objective. We examined the suitability of US and MRA to identify venous occlusion. Materials and methods. We used MRA and ultrasound to examine 11 pediatric patients previously treated for ALL. CVADs had been in place a median of 2.5 years (range, 0.4–2.8 years) and removed a median of 2.1 years (range, 0.6–2.9 years) previously. We also performed 2D time-of-flight magnetic resonance angiography (TOF MRA) on two healthy young adult women with no history of venous abnormality or CVAD use. Results. MRA suggested central venous abnormalities in 8 of the 11 ALL survivors and in both healthy control subjects. US results were negative in all 11 survivors. Conclusion. Further investigation is warranted to develop a sensitive and specific noninvasive method for identifying venous occlusion caused by prior CVAD use. Such a method would allow prospective studies of this complication in pediatric ALL survivors.

Background. Prognosis in neuroblastoma has been shown to correlate with age and stage at diagnosis and site of origin. Extra-abdominal tumors (chest, neck, pelvis) do better in terms of survival than tumors arising from the upper abdomen. Objective. We evaluated a subgroup of abdominal neuroblastomas arising near to the aortic bifurcation (commonly called organ of Zuckerkandl, O. Z.) to assess their biologic outcome and problems in diagnosis and therapy. Materials and methods. Sixteen O. Z. primary tumors were seen at three children's hospitals. Their clinical records and imaging studies were reviewed, including the sonographic, CT, and MRI findings. When available, MYCN amplification was noted (MYCN is the current term previously called N-MYC). Results. Despite more than half of the tumors being very large, survival was the rule, with only one fatality (following multiple local recurrences). Only one patient (who survived) had bone metastases. The larger masses were usually palpated in otherwise well children, while the smaller ones were found in the course of evaluation for unrelated problems such as urinary tract infection. Intraspinal extension was common, though usually asymptomatic. MYCN amplification was absent in the four patients studied. Conclusions. Lower abdominal (O. Z.) neuroblastomas present technical problems of surgical removal, but form a group with a favorable outcome similar to cervical and thoracic primary sites. MRI was useful in delineating intraspinal extension.

Our objective was to offer a preliminary description of MR lymphangiography; its uses and limitations; and its findings in infants, children, and young adults.Twenty-nine patients underwent 32 MR lymphangiographic examinations for evaluation of vascular malformations, other masses, soft-tissue swelling, gigantism, fluid accumulation, or pain. MR lymphangiography was based on a heavily T2-weighted fast spin-echo sequence and a maximum-intensity-projection algorithm. We assessed the axial and off-axial lymphatic channels in conjunction with MR venography to help differentiate veins from lymphatics. Correlation was made with published lymphangiograms and anatomic diagrams to assist interpretation and (when available) with histologic specimens (n = 11) for validation.Presumed lymphatic channels were seen universally, although 14 examinations showed incomplete venous signal suppression. Lymphatic channels appeared normal in eight children and in 20 of the 21 asymptomatic contralateral limbs. Ten patients had an increased number and size of off-axial channels, including seven children with large, diffuse low-flow vascular malformations. Enlarged axial and off-axial channels were seen in five patients, four of whom had Klippel-Trénaunay syndrome. Six patients, each with an extensive hemangioendothelioma, Klippel-Trénaunay syndrome, Gorham syndrome, or unilateral body edema, showed absence or interruption of axial channels.MR lymphangiography appears to be a useful noninvasive technique to study superficial and deep lymphatic channels in children with local or diffuse vascular lesions or swelling of extremities. Its limitations notwithstanding, the technique may offer further insight into the nature of vascular anomalies, may direct therapy, and may predict prognosis.

OBJECTIVE: The purpose of this study is to report our technique for MR cholangiography in children and to describe the postoperative imaging findings in children who have undergone liver transplantation from living related donors. CONCLUSION: MR cholangiography can be used to delineate anatomy and morphology of the bile ducts of the left lateral segment graft in children who have undergone liver transplantation from living related donors. This information can guide treatment of postoperative biliary complications with interventional radiology or surgery.

The purpose of this study was to describe the appearance on magnetic resonance (MR) imaging of hepatic hemangioma, and how the appearance changes in infants who have received interferon alpha-2a (IFN) treatment. We retrospectively studied 16 MR examinations in seven infants (mean age 3.2 months; range 5 days to 13 months) who were symptomatic with hepatic hemangiomas. Five of these seven patients had MR examinations both before and after treatment with IFN. In six of the seven patients, the hepatic hemangiomas were multicentric; they were usually discrete, well-defined nodules, best seen on T2-weighted images as high intensity lesions. One patient had a large solitary heterogeneous lesion. They all exhibited fast flow (seen as flow voids on spin-echo images and high signal intensity structures on gradient-recalled echo images) and enlarged hepatic arteries and veins. There was enlargement of the proximal abdominal aorta with distal tapering. Treatment was followed by accelerated regression of the hemangiomas in size and number and variable shrinkage of the enlarged vessels. As the tumor nodules regressed, they were replaced by normal-appearing hepatic parenchyma; neither fat nor fibrosis was detected by MR imaging.

Twelve children with Wilms tumors were prospectively evaluated with 1.5-T magnetic resonance (MR) imaging. Spin-echo images were obtained before and after administration of gadopentetate dimeglumine. Nine of the 12 children had histologically proved nephroblastomatosis or nephrogenic rests involving a total of 14 kidneys. MR imaging depicted involvement in eight of these kidneys, including five of five kidneys with lesions contralateral to the primary Wilms tumor. Overall sensitivity of detection of nephrogenic rests was 43% on nonenhanced images and 58% when gadolinium-enhanced images were added. Nephrogenic rests admixed with Wilms tumors less than 4 mm in diameter were not depicted at MR imaging. On gadolinium-enhanced T1-weighted images, Wilms tumors and hyperplastic were hypointense to normal renal tissue. On T2-weighted images, Wilms tumors and hyperplastic nephrogenic rests were iso- or slightly hyperintense to renal cortex, while sclerotic nephrogenic rests were hypointense to renal cortex. On all images, including gadolinium-enhanced T1-weighted images, the signal intensity of Wilms tumors was inhomogeneous, while the signal intensity of nephrogenic rests was homogeneous.

Over the last 6 years, 15 percutaneous thoracic biopsies have been performed in 15 children. The peripheral nature of most of the lesions allowed ultrasound guidance in ten and needles larger than 21 gauge in ten. No pneumothorax developed. Of the 15, 12 biopsies were sufficient for final diagnosis; 3 required surgical biopsy for more definitive tissue typing.

This report describes two newborn males with posterior urethral valves, perirenal urinomas and respiratory distress. A 400 cc urinoma was drained percutaneously with resolution of respiratory symptoms in the first case. A 120 cc urinoma was drained in the second case but the infant died of pulmonary hypoplasia at 22 h of age. This report emphasizes the importance of aspirating or draining the urinoma in an attempt to treat the newborn's respiratory insufficiency.

Four children (ages 3-9 years) with intermittent abdominal pain and vomiting are reported. Upper gastrointestinal examinations revealed a sharply angulated to-and-fro course (Z configuration) of the distal duodenum and proximal jejunum, rather than the usual smooth duodenojejunal loop at the ligament of Treitz. At operation this configuration was associated with broad peritoneal bands extending across the involved small intestine without an accompanying volvulus at this level. The Z sign is diagnostic of incomplete rotation, even in the absence of duodenal obstruction and with a proximal jejunum that may appear to be properly placed.

Fifteen children less than 12 kg in weight underwent transplantation of the liver for biliary atresia; eight survived. Five of the eight survivors had thrombosis of the hepatic artery without portal vein thrombosis. Three of the five patients with hepatic artery thrombosis developed infected bilomas, which were drained percutaneously under ultrasonographic (US) or computed tomographic (CT) guidance. Concurrent therapy with antibiotics and hyperoxygenation resulted in resolution of these intrahepatic collections. Although it had been thought that thrombosis of the hepatic artery most often results in necrosis of the graft and requires retransplantation, the five patients in this study survived without retransplantation. Diagnosis of hepatic artery thrombosis was achieved with the use of Doppler US in four cases, CT in four cases, and angiography in two cases. Duplex Doppler US is the preferred imaging modality.