Hybrid SPECT/CT imaging, do we really need it? What is SPECT/CT? Why Hybrid? Attenuation Correction. Hybrid SPECT/CT Provides:

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1 Hybrid SPECT/CT imaging, do we really need it? Rattray Sue Rattray Nuclear Medicine Technologist Princess Alexandra Hospital Brisbane Australia What is SPECT/CT How it works Interesting case examples What is SPECT/CT? Comparing the functional images of Nuclear Medicine with the more anatomical modalities like CT has been done in the past with side-by by-side comparison techniques or by the use of software based fusion, overlaying the two sets of data information. Why Hybrid? Following the success of hybrid PET/CT, hybrid SPECT/CT can combine the functional imaging capabilities of SPECT with the precise anatomical overlay of CT images, all performed in the one imaging session. Hybrid SPECT/CT Provides: Precise IMAGE FUSION for anatomical referencing. Accurate patient specific ATTENUATION CORRECTION, giving better localisation and definition of organs and lesions, resulting in more accurate diagnoses and improved patient management Attenuation Correction Correcting for tissue attenuation requires an accurate measurement of the spatial distribution of attenuation coefficients within the patient. The Hounsfield units from CT data may be used for this, giving improved statistical information, and greater confidence in detection of abnormalities within deeper organs. 1

2 Myocardial Perfusion Scan - Uncorrected Short Axis Corrected for Tissue Attenuation and Scatter Short Axis Vertical Long Axis Vertical Long Axis Horizontal Long Axis Horizontal Long Axis Short Axis Uncorrected Short Axis Vertical Long Axis Corrected Vertical Long Axis Image Fusion Also called image registration or functional anatomical mapping (FAM). Hybrid systems will provide precision alignment of the two sets of image data and eliminate inaccuracies caused by variations in patient position, couch surfaces and the internal changes within the patient from one imaging session to the next. Hybrid SPECT/CT systems 2

3 Multislice hybrid SPECT/CT system (Siemens Medical Systems brochure.) Hybrid SPECT/CT systems Studies have shown SPECT/CT to benefit in the management of patients with a variety of clinical conditions In Oncology, to localise tumour sites, assess invasion into surrounding tissues and demonstrate their functional status Quality CT images allow Radiologists to compare structural detail with isotope activity, potentially giving a differential diagnosis with no further imaging. The range of clinical applications includes Myocardial Perfusion Tc99m Sestamibi, Tc99m Myoview or Thallium201 Skeletal Tc HDP or MDP Neuroendocrine In111 Octreotide Adrenal I123 MIBG Lymphomas and Infections Gallium67 Sentinel Node mapping Tc Colloid Parathyroid Adenomas Tc MIBI And many more.. Case Examples In over 12 months of use we have encountered many interesting cases, some merely unusual, but a large number where the additional information provided by hybrid imaging has either changed or vastly improved upon the quality of the diagnosis. Procedure Bone Scan Anterior and Posterior Whole body bone scan (2 intensities) Patient with history of Breast Carcinoma, and low back pain. Dose of 865 MBq Tc99m HDP given. Delayed whole body and spot views of ribs and skull plus SPECT imaging and low dose non-diagnostic CT of Lumbar Spine for lesion localisation. 3

4 Transverse SPECT slices at L5/S1 3 view display SPECT, CT and fused SPECT/CT Fusion Zoomed CT slice Outcome - Localisation of activity in the Lumbar spine SPECT/CT fusion images distinguished facet joint arthropathy from Pars fractures therefore targeting the treatment outcomes Also indicated that metastases from the breast primary were unlikely. Procedure Bone Scan 17 yr old female with increasing low back pain and raised ESR. Dose of 802 MBq Tc99m HDP given. Three phase bone scan of the spine and pelvis, plus SPECT imaging and low dose non-diagnostic CT of Lumbar Spine for lesion localisation. 4

5 Planar static views SPECT Transverse slices 3 view display SPECT, CT and fused Magnified CT slice with calcification in soft tissue Findings Marked increased uptake is seen just to the left of midline and centred on L3. SPECT images locate the foci to the spinous process on the left and posterior to the facet joint of L3/4. CT shows the joint and spinous process are unchanged, with the lesion lying within the left Para spinal muscle. MRI showed an enhanced lesion on T1 and T2 suspicious of an infective process. A Biopsy performed under fluoroscopy was inconclusive. Follow-up MRI was more in keeping with a Benign Heterotropic ossification or Myositis Ossificans CT found the ossification to have progressed, with an increase in size, but no aggressive features were demonstrated. 5

6 T2 weighted MRI Repeat CT scan at 5 months Procedure Bone Scan Anterior and Posterior Whole body bone scan (2 intensities) Patient with a history of Prostatic Cancer and a PSA of 15,? Metastases. Dose of 843 MBq Tc99m HDP given. Delayed whole body and spot views of ribs and skull plus SPECT imaging and low dose non- diagnostic CT of Lumbar Spine for lesion localisation. Planar static views SPECT Transverse slices 6

7 3 view display SPECT, CT and fused CT slice of Sacrum Findings Small area of intense uptake at the right inferior sacrum, localised to a sclerotic lesion on the fusion CT, consistent with skeletal metastases. Degenerative uptake in the right shoulder joint, mid and lower lumbar spine, both knees and the left wrist. Procedure Bone Scan 85 yr old patient with a history of Prostatic Cancer and a rising PSA? Metastases. Dose of 843 MBq Tc99m HDP given. Delayed whole body and spot views of ribs, skull and pelvis, plus SPECT imaging and low dose non-diagnostic CT of Pelvis for lesion localisation. Planar static views Lateral Pelvis Anterior and Posterior Whole body bone scan 7

8 SPECT Transverse slices 3 view display SPECT, CT and fused CT slices of Pelvis CT slices of Pelvis 8

9 Findings Degenerative changes in cervical and lumbar spine Paget s s disease in right hemipelvis Bladder diverticulum within a right inguinal hernia No evidence of metastatic disease White Blood Cell labelled scan of Polycystic Kidneys Patient received 809 MBq Tc 99m Labeled autologous white blood cells. One hour and three hour planar images were performed, with SPECT/CT imaging of the abdomen for lesion localization. 3 hour Static images 3 view display SPECT, CT and fused 9

10 Findings There is no abnormal tracer uptake in the kidneys. Low grade tracer uptake in the stomach and thyroid gland likely artifact from free Pertechnetate. Note is made of the kidney and liver disease on the CT scan. Procedure Gallium 67 scan Patient presented with left otitis externa, suspected osteomyelitis left temporal bone and facial nerve palsy. A three phase bone scan was performed, followed by a Gallium67 infection study. Planar static views Bone scan - Transverse slices Blood Pool 2 hr Bone 48 hr Ga67 Findings Bone Scan Gallium 67 Coronal and Transverse slices Moderate increased tracer uptake at the left base of skull likely osteomyelitis. CT localised the activity to the left mastoid process, and ruled out Pagets. Other skeletal activity attributed to Pagets disease Low grade activity also seen on the Gallium scan. 10

11 3 view Gallium fusion images 3 months repeat A repeat Gallium scan at 3 months after intensive antibiotic therapy showed only very mild uptake in the region of the left mastoid. Procedure Parathyroid Scan 39 yr old female with hypercalcaemia secondary to hyperparathyroidism 5 days post caesarean section. Scheduled for urgent surgery. Technique Patient received 831 MBq Tc 99m Sestamibi and 196 MBq Tc99m Pertechnetate. Early and delayed planar images were performed. SPECT imaging and low dose non diagnostic CT was performed of the neck and chest for lesion localization. Pinhole and Planar images of neck and chest 3 view display SPECT, CT and fused 11

12 Zoomed CT image Findings A large focus of increased uptake related to the upper pole of the right thyroid is present on all phases of imaging CT correlates this with a corresponding low density lesion of approximately 2cm diameter in the right paraoesophageal groove. Procedure In111 Octreotide scan Follow up scanning for patient with known metastatic Gastrinoma 151MBq Indium111 Octreotide given Whole body and abdomen images obtained at 4 and 24 hours SPECT/CT of the chest and abdomen 4 hour Planar statics Transverse SPECT slices SPECT / CT fused Transverse slices 12

13 Findings Multiple sites of Octreotide avid disease in the Liver, showing progression from the previous studies SPECT/CT localises these areas, but also demonstrates one lesion on the CT which is not avid for Octreotide, a PET scan was recommended. Sentinel Lymph node study Static images immediate and delayed Patient with known melanoma in the right posterior auricular region 20MBq Tc99m Antimony Sulphur Colloid given in four intra-dermal injections Early and delayed static imaging performed, plus SPECT/CT of the head and neck. 3 view display SPECT, CT and fused Triangulation of SPECT and CT 13

14 Findings Moderate tracer uptake seen on the right, slightly inferiorly to the injection site SPECT/CT localised this to a 5x3 mm infra-parotid node, posterior to the mandible Marked on the skin with ink. Incidental findings on SPECT/CT scans The diagnostic quality of the CT portion of the imaging process allows visualisation of other structural abnormalities, most often normal variants or pre existing pathologies. However, these must still be commented upon in the reporting CT for Myocardial Perfusion study cysts in liver Calcified Plaques typical of Asbestosis Surgical clips in resected Liver Secondaries Bone Scan Patient with low back pain showed uptake in posterior ribs 14

15 Large mass in Rt lower lobe AAA Practical Implications Costs Space Radiation Protection Staff training Projected uses Acknowledgments Greg Rattray my husband, for allowing me to pick his brains Dr. Stanley Ngai for his help with CT interpretation Michelle Jenkins for access to her collection of interesting cases. 15

16 References CT/SPECT scanner installation PAH Department Keidar Z, Israel O, Krausz Y, SPECT/CT in Tumour Imaging: Technical Aspects and Clinical Applications. Seminars in Nuclear Medicine 33(3):p205 O Connor, M and Kemp, B, Single-Photon Emission Computed Tomography/ Computed Tomography: Basic Instrumentation and Innovations. Seminars in Nuclear Medicine 36(4), p Schillaci O, Danieli R, Manni C, Simonetti G, Is SPECT/CT with a hybrid camera useful to improve Scintigraphic imaging interpretation? Nuclear Medicine Communications 25(7): p Griffiths M, Lee A, SPECT/CT hybrid imaging: Technology, techniques and clinical experience. Synergy Jan 2006 p PAH Department installation console area Come to Australia for 16 th ISRRT World Congress Gold Coast - Australia Tomorrow and Beyond: Connecting and Communicating 9 12 September, 2010 For enquiries events@air.asn.au See us at the booth in Durban