Diffuse Elevated MIBG Activity in the Renal Parenchyma Caused by Compromised Renal Blood Flow

Unusual Renal Uptake of 131 I-MIBG in a Young Hypertensive With Renal Artery Stenosis

ABSTRACT

A 10-year-old hypertensive girl underwent 131 I-MIBG scan to rule out neural crest derived tumor. The whole-body images revealed diffuse intense tracer uptake in the right kidney, which persisted in 96-hour images as well. CT renal angiography revealed 90% to 95% right renal artery stenosis. Thereafter, she underwent baseline and angiotensin receptor blockade renal dynamic imaging, which revealed hemodynamically significant renal artery stenosis. Pattern of diffuse and intense 131 I-MIBG uptake, albeit rare, still warrants further evaluation to rule out renal artery stenosis and investigate its hemodynamic significance for appropriate management.

Current Status and Future Perspective on Molecular Imaging and Treatment of Neuroblastoma

Neuroblastoma is the most common extracranial solid tumor in children and arises from anywhere along the sympathetic nervous system. It is a highly heterogeneous disease with a wide range of prognosis, from spontaneous regression or maturing to highly aggressive. About half of pediatric neuroblastoma patients develop the metastatic disease at diagnosis, which carries a poor prognosis. Nuclear medicine plays a pivotal role in the diagnosis, staging, response assessment, and long-term follow-up of neuroblastoma. And it has also played a prominent role in the treatment of neuroblastoma. Because the structure of metaiodobenzylguanidine (MIBG) is similar to that of norepinephrine, 90% of neuroblastomas are MIBG-avid. 123I-MIBG whole-body scintigraphy is the standard nuclear imaging technique for neuroblastoma, usually in combination with SPECT/CT. However, approximately 10% of neuroblastomas are MIBG nonavid. PET imaging has many technical advantages over SPECT imaging, such as higher spatial and temporal resolution, higher sensitivity, superior quantitative capability, and whole-body tomographic imaging. In recent years, various tracers have been used for imaging neuroblastoma with PET. The importance of patient-specific targeted radionuclide therapy for neuroblastoma therapy has also increased. 131I-MIBG therapy is part of the front-line treatment for children with high-risk neuroblastoma. And peptide receptor radionuclide therapy with radionuclide-labeled somatostatin analogues has been successfully used in the therapy of neuroblastoma. Moreover, radioimmunoimaging has important applications in the diagnosis of neuroblastoma, and radioimmunotherapy may provide a novel treatment modality against neuroblastoma. This review discusses the use of current and novel radiopharmaceuticals in nuclear medicine imaging and therapy of neuroblastoma.

MIBG Uptake in Pancreas as a Normal Variant

ABSTRACT

A 5-year-old girl with high-risk neuroblastoma underwent 123I-MIBG scintigraphy for disease restaging. The whole-body images showed a faint MIBG uptake in the midabdomen. Abdominal SPECT/CT demonstrated the focus locating in the pancreatic head. However, this activity disappeared on delayed acquisition at 6-hour later. Follow-up MIBG scan after 6 months did not show the abnormal MIBG uptake in the pancreatic head. Delayed scan could be helpful for differential diagnosis.

Renal 123I-MIBG Uptake before and after Live-Donor Kidney Transplantation

Increased sympathetic activity is suggested to be part of the pathogenesis in several diseases. Methods to evaluate sympathetic activity and renal nervous denervation procedural success are lacking. Scintigraphy using the norepinephrine analog Iodine-123 Metaiodobenzylguanidine (123I-MIBG) might provide information on renal sympathetic nervous activity. Renal transplantation induces complete denervation of the kidney and as such represents an ideal model to evaluate the renal 123I-MIBG scintigraphy method. The aim of this study was to evaluate whether renal 123I-MIBG scintigraphy can detect changes in renal sympathetic nervous activity following renal transplantation. Renal 123I-MIBG scintigraphy was performed in eleven renal transplant recipients at 1, 3, and 6 months following transplantation and in their respective living donors prior to their kidney donation. Relative uptake as well as washout was obtained. In transplanted patients, the relative 4 h uptake of 123I-MIBG, as measured by the kidney/background ratio, was 2.7 (0.4) (mean (SD)), 2.7 (0.5), and 2.5 (0.4) at 1, 3, and 6 months post-transplantation, respectively, as compared with the 4.0 (0.4) value in the donor kidney before donor nephrectomy (p < 0.01). There was no significant change in washout-rate between pre-transplantation and any of the follow-up time points. Living donor kidney transplantation was at 6 months post transplantation, associated with an almost 40% reduction in the relative 4 h 123I-MIBG uptake of the kidney. Further studies will help to fully establish its implications as a marker of renal innervation or denervation.

Roles of PET/Computed Tomography in the Evaluation of Neuroblastoma

Neuroblastoma is one of the most common pediatric malignant tumors. Functional imaging plays an important role in the diagnosis, staging, and therapy response monitoring of neuroblastoma. Although metaiodobenzylguanidine scan with single-photon emission computed tomography/computed tomography remains the mainstay in functional imaging of the neuroblastomas, PET/CT has begun to show increased utility in this clinical setting.

Renal Metastasis From Neuroblastoma Shown on MIBG Imaging

A 6-year-old girl with high-risk neuroblastoma underwent a I-MIBG scan to monitor the disease status. In addition to the known lesion in the right retroperitoneal region, there were additional foci of increased activity in the right upper quadrate of the abdomen, which were not typical bowel activity. SPECT/CT images located the activity in the cortex of the lower pole of the right kidney, which was partially calcified. Subsequent biopsy confirmed neuroblastoma metastasis to the right kidney, which is extremely rare.

SPECT/CT MIBG Imaging Is Crucial in the Follow-up of the Patients With High-Risk Neuroblastoma

BACKGROUND

Planar whole-body imaging with I-radiolabeled metaiodobenzylguanidine (I-MIBG) is routinely used in the follow-up evaluation of neuroblastoma. In recent years, SPECT with integrated low-dose CT (SPECT/CT) has become more accessible. We investigated how much SPECT/CT can have additional diagnostic value over planar imaging in detection of residual and recurrent neuroblastoma.

METHODS

A total of 170 planar I-MIBG imaging scans with SPECT/CT follow-up scans performed in 147 patients with known high-risk neuroblastoma were retrospectively analyzed. Regions of increased I-MIBG uptake on planar images and the findings on SPECT/CT were compared.

RESULTS

In 61% of the studies, the whole-body planar images and SPECT/CT images yielded the same result. In 39% of the time, however, SPECT/CT images provided additional information.

CONCLUSIONS

In the follow-up of patients with high-risk neuroblastoma, SPECT/CT can significantly improve planar imaging interpretation and impact patient management.

Prominent Pulmonary Metastases Without Concurrent Osseous Involvement in Patients With High-Risk Neuroblastoma

Metastases from high-risk neuroblastomas generally are to the bone or bone marrow. Multiple lung metastases are rare, especially when there was no concurrent osseous metastasis. We report 2 cases of high-risk neuroblastomas having prominent lung metastases without concurrent osseous lesion observed.

Acrometastasis of Neuroblastoma to the Great Toe Revealed by MIBG Scan

A 3-year-old boy with history of neuroblastoma underwent I-MIBG scan. The whole-body images showed relatively normal tracer distribution except for mild activity in the right foot, which was located in the first metatarsal on SPECT/CT images. The subsequent MRI scan of the right foot showed infiltration of the metatarsal of the right first toe. The findings were consistent with solitary acrometastasis of neuroblastoma to the great toe.