SPECT/CT: I 123 MIBG

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Ross Campbell
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1 Dose reduction and SPECT/CT in Pediatrics for Clinicians and Technologists SPECT/CT: I 123 MIBG non diagnostic CTscanner Zvi Bar Sever MD Schneider Children s Medical Center, Israel

2 Neuroblastoma MIBG scans in children are used predominantly for neuroblastoma Most common extra cranial solid tumor in young children (8% of childhood cancers in the USA) Primary tumor origin and sites Embryonal malignancy arising from neuroblasts (pluripotent sympathetic cells) 40% adrenals, 25% paraspinal ganglia, 15% thoracic, 5% pelvic, 3% cervical, 12% miscellaneous Tumor spread 70 80% of children older than 1 year present with metastatic disease at diagnosis (lymph nodes, liver, bone, bonemarrow)

3 Neuroblastoma MIBG, a norepinephrine p analog, is both sensitive and specific for neuroblastoma MIBG is routinely used in staging, monitoring response to therapy and long term follow up

4 Planar imaging Evolution of MIBG imaging in neuroblastoma anterior posterior posterior anterior Large primary tumors Skeletal disease Distinct soft tissue metastases mostly etraabdominal extra abdominal posterior anterior Case A I 131 MIBG I 123 MIBG

5 Evolution of MIBG imaging in neuroblastoma SPECT Increases sensitivity Improves detection of small lesions especially those overlying areas of high activity (liver, bladder, primary tumor) Improves distinction between soft tissue and dseeta skeletal lesions s especially around aou dthe spine Case C Case C

6 Evolution of MIBG imaging in neuroblastoma Hybrid imaging Flexible software co registration Rigid Hardware co registration Inter modality Intra modality co registration co registration MIBG MRI MIBG Bone MIBG CT MIBG SPECT/CT transaxial sagittal coronal low dose CT scanner transaxial transaxial sagittal sagittal coronal coronal Diagnostic CT CT MRI Bone SPECT Attenuation correction Anatomical localization Bridging co registration MIBG MIBG SPECT MIBG Fused Fused CT bone MIBG MIBG Fused MIBG MRI

7 MIBG SPECT CT imaging Camera and protocol Infinia Hawkeye 4 GE Medical Systems Dual head gamma camera with a 4 slice low dose CT CT prameters 14O KV, 2.5 ma 5 min per field of view (40 cm) 0.5 cm slice thickness SPECT parameters 120 projections, 25 sec/projection 128X128 matrix Iterative reconstruction Co registered dimages displayed d on a Xl Xeleris 2 work station (GE Medical Systems) Dosimetry Patient CT dose ~ 2 msv (according to manufacturer data) MIBG patient dose 3.7 msv (for a 5 year old receiving 100 MBq)

8 Clinical cases The added value of low dose MIBG SPECT/CT

9 I-123 MIBG at diagnosis MIP 6 year old boy Huge abdominal neuroblastoma posterior anterior Case 1 ED

10 Following 3 months of thearpy posterior anterior Case 1 ED

11 renal pelvis Case 1 ED

12 I-123 MIBG 12 year old boy Non resectable, stage 3, stable abdominal neuroblastoma anterior posterior Case 2 MCh

13 primary tumor Case 2 MCh

14 new new focus focus Case 2 MCh

15 right adrenal Case 2 MCh

16 4.5 year old boy HR metastatic Neuroblastoma in remission anterior posterior Case 3 VI

17 MIP Case 3 V

18 bowel Case 3 V

19 7 year old boy HR metastatic neuroblastoma in remission, post therapy Case 4 MS

20 Left liver lobe Case 4 MS

21 Left liver lobe MIP Case 4 MS

22 anterior posterior 2 year old girl Stage 4 abdominal neuroblastoma Excellent response to chemotherapy Focal uptake right axilla/chest wall? Case 5 MM

23 Central line port artifact Case 5 MM

24 6 year old girl HR metastatic abdominal neuroblastoma New uptake left upper chest Case 6 AN

25 Case 6 AN

26 Case 6 AN

27 The role of MIBG SPECT/CT in children with neuroblastoma Bar Sever, Steinmetz, Ash, Yaniv & Kornreich SNM annual meeting New Orleans June 2008 Purpose: to evaluate the added value of SPECT/CT over SPECT in MIBG scans of children with neuroblastoma Stand alone SPECT and SPECT CT from 32 MIBG studies of 22 children were reinterpreted blindly Foci of increased MIBG uptake not clearly related to physiologic uptake were graded according to their likelihood of representing malignancy. The confidence in the interpretation of every focus was graded as high, low or intermediate 52 soft tissue sites separate from the primary tumor were recorded SPECT/CT improved localization in 40 sites (77%)

28 Distribution of diagnostic confidence levels for non primary tumor soft tissue site interpretations Diagnostic confidence level SPECT number of sites SPECT/CT p=0.042 high intermediate confidence level low 0

29 Non primary tumor soft tissue site analysis Distribution of benign, indeterminate and malignant site interpretations SPECT SPET/CT no. of sites 5 p<0.001 malignant indeterminate benign category 0

30 Distribution of benign sites 9% 11% liver central line 36% adrenal glands 19% bowel renal pelvis 25%

31 The role of MIBG SPECT/CT in children with neuroblastoma Bar Sever, Steinmetz, Ash, Yaniv & Kornreich SNM annual meeting New Orleans June 2008 SPECT/CT excluded malignancy in 25/52 soft tissue sites (48% of all sites) considered indeterminate (18) or malignant (7) on SPECT Conclusions SPECT/CT improved the diagnostic accuracy of I 123 MIBG scans in children with neuroblastoma It yielded yededa significantly sg tylower number of indeterminate and malignant agat interpretations compared with SPECT The diagnostic confidence level was significantly higher on SPECT/CT interpretations compared to SPECT The main incremental value over SPECT was in excluding malignancy in sites of physiologic and benign uptake in the soft tissues It had no major impact on the interpretation of skeletal disease

32 MIBG Low dose SPECT/CT pros and cons Pros Improved diagnostic accuracy Very low CT dose Improved dinterpretation t ti outweighs the small additional radiation dose Cons Limited anatomical CT information due to Low CT resolution Multiple artifacts mostly in the upper abdomen in small children Lack of contrast Increased need for sedation/anesthesia

33 Bridging co registration Softwareco registration registration betweenthe the SPECT/CT and an external CT Low dose Hawkeye CT is registered to the diagnostic CT and serves as a bridge to accurately co register the MIBG SPECT to an external diagnostic CT

34 Diagnostic CT Diagnostic CT Low dose CT Fused CT Low dose CT Fused CT Diagnostic CT Low dose CT Volumetric IR, GE Medical System Fused CT

35 MIP anterior projection 15 year old girl with relapsed neuroblastoma Case 7 AT

36 MIP anterior projection Case 7 AT

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