title: 111In-pentetreotide scintigraphy in medulloblastoma: a comparison with magnetic resonance imaging.
abstract: Medulloblastoma (MB) is a primitive neuroectodermal tumour constituting a grade IV brain malignancy. Early and correct detection of recurrence or metastasis is desirable for follow-up of patients in this entity. Frequent expression of somatostatin receptors by MB lesions facilitates functional tumour imaging by somatostatin receptor scintigraphy (SRS). To investigate the value of SRS in the follow-up of MB, the results of ten consecutive patients (seven children and three adults) undergoing additional imaging with 111In-pentetreotide were reviewed. Four, 24 and 48 h p.i. planar and whole body images as well as a SPECT study at 4 h p.i. were acquired after intravenous injection of 109 +/- 35 MBq 111In-pentetreotide (Octreoscan). SRS yielded 11 positive and ten negative imaging results, compared to 17 positive and four negative in magnetic resonance imaging (MRI). The lesion-by-lesion analysis with a total of 44 lesions revealed a sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 42%, 83%, 94%, 18% for SRS and 89.5%, 50%, 92%, 43% for MRI. Based on a per-patient analysis, considering the patient as to be either tumour-free or tumour-positive by one imaging modality, the following values for sensitivity, specificity, PPV and NPV were obtained: 61%, 100%, 100%, 30% for SRS and 94%, 67%, 94%, 67% for MRI. MRI remains the first step imaging technique in medulloblastoma patients before and after surgery and during the follow-up providing the highest sensitivity. However, to improve specificity and contribute to correct diagnosis in MB 111In-pentetreotide scintigraphy should be considered as a confirmatory second step imaging tool, especially in case of equivocal MRI results. Moreover, a positive SRS scan might serve as a reference before and after somatostatin receptor targeted radiotherapy.
authors: Trakya University Medical Faculty, Department of Nuclear Medicine, Edirne, Turkey. mahmuty@trakya.edu.tr
authors: Mahmut
authors: M
authors: Yüksel
authors: Götz
authors: G
authors: Lutterbey
authors: Hans Jürgen
authors: HJ
authors: Biersack
authors: Urs
authors: U
authors: Elke
authors: Carola
authors: C
authors: Hasan
authors: Zairong
authors: Z
authors: Gao
authors: Udo
authors: U
authors: Bode
authors: Samer
authors: S
authors: Ezziddin
mesh_terms: D000293:Adolescent; D000328:Adult; D002528:Cerebellar Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008527:Medulloblastoma / Q000175:diagnosis* / Q000000981:diagnostic imaging; D011237:Predictive Value of Tests; D017481:Receptors, Somatostatin; D012680:Sensitivity and Specificity; D013004:Somatostatin / Q000031:analogs & derivatives*; D015899:Tomography, Emission-Computed, Single-Photon; D051598:Whole Body Imaging
chemical_list: D017481:Receptors, Somatostatin; D013004:Somatostatin; C081788:pentetreotide