Radiation dose reduction thanks to split-bolus multi-detector computer tomography (MDCT) in children with non-thoracic neuroblastoma

Abstract

Federico et al. concerning with the role of chest computed tomography (CT) in the surveillance of children affected by highrisk neuroblastoma.[1] According to the authors, the omission of surveillance chest CT imaging can save 35-42% of the radiation burden without compromising disease detection in those patients with non-thoracic high-risk neuroblastoma at diagnosis.[1] We have developed a novel split-bolus technique for multi-detector computer tomography (MDCT) able to reduce the radiation dose and to ensure diagnostic accuracy in case of non-thoracic neuroblastoma. It combines in a single pass the arterial and venous phases, allowing the detection of hypo-or hyper-vascular lesions, together with lymph node involvement and related distant metastases.[2-3] The split-bolus 64-detector row CT protocol is based on a single acquisition of the chest-abdomen-pelvis after intravenous injection of 2 ml/kg of contrast medium (Iopamiro 350 mg/ml; Bracco, Milan, Italy), split by an automatic power injector (Medrad Stellant, Indianola, PA) into two boluses. We have applied this protocol in a 45-kg and 14-year-old patient for the detection of a retroperitoneal neuroblastoma, whose diagnosis was subsequently confirmed on the surgical specimen by histology. The first bolus consisted of 54 ml contrast material injected at 1.3 ml/sec and followed by 15 ml saline solution at the same flow rate, in order to obtain an adequate parenchymal and venous enhancement. The second bolus consisted of 36 ml contrast material administrated at 1.3 ml/sec and followed by 15 ml saline solution at the same flow rate, in order to obtain the late arterial phase. A manual bolus tracking was set up, raising the threshold value at 500 HU, by placing a circular region of interest (ROI) in the descending aorta. The scan was cranio-caudally performed, starting from the pulmonary apex toward the pubic symphysis, after a 6 sec delay from the arrival of the contrast material in aorta. The inherent delay in the bolus tracking was necessary to move the scan table, give breath-hold instructions to the patient, and tune the gantry parameters. The following acquisition parameters were applied: gantry rotation speed 0.75 sec; slice thickness 2.5 mm; reconstruction index 1.25; pitch 0,935:1; tube voltage 120 kVp with automatic tube current (mA) using z-axis modulation. The examination was completed with axial, coronal and sagittal multiplanar reconstructions (Fig. 1).The split-bolus MDCT allowed tumor detection and its extension, without compromising the disease staging in this patient. The dose length product (DLP) was 98.1 mGy.cm and this led us to support the rationale proposed by Federico et al. aimed to possibly avoid a radiation burden, [1] in particular in children affected by non-thoracic neuroblastoma. Moreover, by combining the split-bolus MDCT in the diagnostic phase to the proposed surveillance criteria, a further radiation dose reduction could be Fig. 1. Split-bolus whole body MDCT: the axial (A), coronal (B), and sagittal (C) multiplanar reconstructi...

Value of split-bolus multidetector-row CT technique in the quantitative assessment of pancreatic enhancement

“…MCDT is the procedure of choice in the identification of pancreatic malignancy 6 and other unusual tumors 7,8 . CT, in particular, is the method of choice in the assessment of normal pancreatic parenchyma and in the detection and staging of pancreatic adenocarcinoma 9,12,20 .…”

“…the most widely used method for the evaluation of pancreatic and non-pancreatic neoplastic diseases [6][7][8] . In this setting the knowledge of magnitude and consistency of the normal pancreatic enhancement and of optimal contrast differences between pancreas tumor and pancreas parenchyma is essential to ensure detection of lesions and accurate evaluation of peripancreatic vessels or lymph nodes 9,10 .…”

Value of Triphasic MDCT in the Differentiation of Small Renal Cell Carcinoma and Oncocytoma

“…The association with single photon emission CT (SPECT) can be helpful in the diagnosis of rare renal tumors (11). Recently, split-bolus MDCT technique has been proposed by splitting intravenous contrast medium into two to three boluses and combining phase images in a single scan, achieving a significant dose reduction to the patient (12-15).…”

Reply to: Radiation dose reduction thanks to split-bolus multi-1 detector computer tomography (MDCT) in children with non-thoracic neuroblastoma

“…To the Editor: We thank Scialpi and colleagues for their letter supporting the premise of limiting radiation exposure from computed tomography in children with high‐risk neuroblastoma. In their letter, they describe a new technique of administering a split bolus dose of contrast when performing computed tomography (CT) . They propose that this technique, as demonstrated in a single 14‐year‐old patient, leads to decreased radiation exposure delivered by CT.…”

“…In their letter, they describe a new technique of administering a split bolus dose of contrast when performing computed tomography (CT). [1] They propose that this technique, as demonstrated in a single 14-year-old patient, leads to decreased radiation exposure delivered by CT. While we commend the authors for attempting to decrease radiation exposure from CT, we have questions about the technique described and the relevance to our manuscript, "The role of chest computed tomography (CT) as a surveillance tool in children with high-risk neuroblastoma."…”