Disclosures No relevant financial disclosures Diffusion and Perfusion Imaging in the Head and Neck Ashok Srinivasan, MD Associate Professor Director of Neuroradiology University of Michigan Health System Learning objectives 43 y/o M status post parotidectomy Review technical aspects and challenges of and perfusion imaging Discuss clinical applications in the head and neck??? MRI weighted imaging Imaging of of water molecules Strong gradients in 3 orthogonal directions MRI Perfusion imaging ADC (Apparent coefficient) Expressed in mm 2 /s CT Perfusion Higher the ADC, more is the degree of motion (and vice versa)
ECHO-PLANAR IMAGING Single shot- Limited spatial resolution, greater geometric distortion, shorter acquisition Multi shot- Higher resolution, reduced geometric distortion, longer acquisition ECHO-PLANAR AXIAL plane 4 mm slice thickness 0.5 mm intersection gap AP phase encoding direction Challenges with DWI neck NON ECHO-PLANAR HASTE PROPELLER BLADE Less susceptibility artifact Thinner sections, higher imaging matrices Longer acquisition Lower signal to noise ratio Susceptibility artifacts Parallel imaging Minimize echo train length (duration of recording) Geometric distortions (especially at root of neck) Read out segmented EPI, Reduced FOV DWI CLINICAL APPLICATIONS?Surrogate marker for cellularity Benign vs. malignant lesions Less cellularity (Benign) More cellularity (Malignant) HIGHER ADC LOWER ADC
Pleomorphic adenoma T2-weighted Pre-Gad T1-weighted Post Gad T1-weighted Adenocarcinoma Post-Gad T1-weighted b800 ADC = 1.5 x 10-3 mm 2 /s ADC = 0.7 x 10-3 mm 2 /s Basal cell adenocarcinoma 19 y/o female with LE tingling and numbness Post Gad T1-weighted Venous vascular malformation High grade acinic cell CA parotid with left level II metastatic node Tagged RBC scan T2-weighted Post Gad T1W
Benign vs. malignant lesions 65 y/o M with stridor and laryngeal mass MAL BEN 0.5 0.75 1.0 1.25 1.5 ADC ADC value of 1.3 x 10 3 mm 2 /s at 3T? threshold value for differentiation 65 y/o M with stridor and laryngeal mass Mucoepidermoid carcinoma T2-weighted Post Gad T1-weighted High ADC- Chronic inflammation Chondrosarcoma Paraganglioma T2W Post Gad T1-weighted Post Gad T1-weighted
CLINICAL APPLICATIONS POST-THERAPY Benign vs. malignant lesions Post-therapy changes vs. recurrence Patient 1 Patient 2 T1-w Post-Gad T1-w Post- Rx enhancing mass T2-w Post-Gad T1-w POST-THERAPY POST-THERAPY Patient 1 Patient 1 ADC = 0.8 x 10-3 mm 2 /s Biopsy proven recurrence Patient 2 Post-GadT1-w DWI Patient 2 ADC = 1.8 x 10-3 mm 2 /s Biopsy: Benign granulation POST-THERAPY 82 y/o F ADC can be helpful in differentiating residual or recurrent tumor from post therapy changes H/o Large cell Lymphoma and neutropenia Residual or recurrent tumor Post-therapy changes ADC ADC ADC of 1.30 x 10 3 mm 2 /s as a threshold High ADC- Likely benign
Two patients- both with new mass in the surgical bed post parotidectomy 43 y/o M status post parotidectomy Pt.1 Restricted (low ADC)- Path proven recurrence Post Gad T1-weighted T2-weighted Pt.2 High ADC- No malignancy on path High ADC- No malignant cells on path CLINICAL APPLICATIONS Benign vs. malignant lesions Post-therapy changes vs. recurrence Prediction of therapy Monitoring of response PREDICTION OF RESPONSE PRE-TREATMENT ADC COMPLETE responders PARTIAL responders 1.04 x 10-3 mm 2 /s 1.35 x 10-3 mm 2 /s Significant in ADC in complete responders within 1 week of treatment Prediction of response Pre-Rx ADC and change in ADC INTRA-THERAPY Pt.1 ADC = 0.8 x10 3 ADC - Monitoring early therapeutic response Pt.2 ADC = 1.4 x10 3 Increase in ADC during early phase of therapy relative to baseline value suggesting conversion of solid tumor to necrotic tissue
Intra therapy tumor response assessment CLINICAL APPLICATIONS Benign vs. malignant lesions Rx Post-therapy changes vs. recurrence Prediction of therapy Monitoring of response Recurrent cholesteatoma Post mastoidectomy for cholesteatoma Post-Op for petrous apex cholesteatoma Recurrent Cholesteatoma + Scar Recurrent Cholesteatoma + Scar CLINICAL APPLICATIONS Benign vs. malignant lesions Post-therapy changes vs. recurrence Prediction of therapy Monitoring of response Recurrent cholesteatoma Intraocular abscess Miscellaneous
Melanoma, Evaluate brain metastases Extracranial and brain metastases present MRI weighted imaging MRI Perfusion imaging MR Perfusion DCE Technique With or without contrast administration T2*- Dynamic susceptibility contrast or T1 - Dynamic contrast enhanced Blood flow and blood volume, capillary permeability and transfer coefficients Axial plane 2D-multislice, T1-weighted fast-field echo 3D spoiled Gradient T1-weighted Slice thickness of 5-6 mm (3 mm overlap) Craniocaudal length of coverage 5 to 6 cm 0.1 mmol/kg of Gadolinium at 5 ml/sec Then, 20 ml saline flush at 5 ml/sec
Patient motion MR Perfusion - Challenges MRI Perfusion imaging Benign vs. malignant Skull base susceptibility artifacts Good cardiovascular function Good renal function Values are relative, so semi-quantitative DSC % threshold value Could be helpful for differentiating malignant from benign nodes and metastatic from lymphomatous nodes Mean DSC% of malignant tumor >> Mean DSC% of benign lesions Ve WIR Razek AA et al. Eur J Radiol. 2011;77:73-79. Razek AA et al. JCAT 2011;35:21-25. MRI Perfusion imaging Prediction of outcome using DCE MRI Benign vs. malignant Prediction of outcome MRI scans before therapy and 2 weeks into chemo-rt Blood volume in the primary tumor after 2 weeks of chemo-rt was increased significantly in the local control patients compared with the local failure patients (p < 0.03) Reduction in tumor volume after 2 weeks of chemo-rt did not predict local control Cao Y et al. Int J Radiat Oncol Biol Phys. 2008;72:1287-90.
Pre-Tx During Tx Post-Tx 1 0.9 0.8 Pre-Rx HIGH K(TRANS) COMPLETE RESPONSE 0.7 0.6 0.5 0.4 Blood volume Blood volume Blood volume 0.3 0.2 0.1 0 Pre-Rx LOW K (TRANS) PARTIAL RESPONSE (Courtesy: Srinivasan et al. Biologic imaging of head and neck cancer. AJNR 2012;33:586-94) Kim S et al. AJNR 2010;31:262-8. MRI Perfusion imaging Benign vs. malignant Prediction of outcome Recurrent tumor versus Post-therapy benign changes DCE MR perfusion Post-therapy benign changes showed TTP & RWO (relative washout ratio) than recurrent tumor Recurrent tumor Furukawa et al. Head Neck 2013;35:923-929. Recurrent squamous cell carcinoma MRI weighted imaging WIR TTP MRI Perfusion imaging CT Perfusion
CT Perfusion Requires contrast administration and dynamic imaging Post-processing using deconvolution algorithm Blood volume, blood flow, mean transit time, time to peak, capillary permeability CT Perfusion - Technique Cine mode 40 mm detector coverage 5 mm slice thickness 50 cc Non-ionic contrast at 4 cc/s 20 cc saline flush at 4 cc/s 5 sec delay 50 sec scan duration CT Perfusion - Challenges Patient motion Z axis coverage limited Streak from dental amalgam Good renal function Pre-Rx Higher BF and BV correlate with better response BV correlates with microvascular density, an important prognostic indicator CP correlates with EGFR overexpression Post Rx Responders show lower BV and BF Ash L et al. Radiology 2009;251:422-428. Zima A et al. AJNR 2007;28:328-334. Surlan-Popovic K et al. AJNR 2010;31:570-575. Jin G et al. J Comput Assist Tomogr 2011;35:26-30. CT Perfusion CT PERFUSION Thrombosed vein CT PERFUSION Post treatment Post treatment Blood volume Blood flow Blood volume Permeability Increased blood volume and blood flow recurrent tumor Increased blood volume and permeability residual tumor
Summary Always interpret /perfusion imaging along with anatomic information Pre-Rx During Rx Post Rx Low ADC- Malignant Low ADC Elevated blood volume/k-trans Good prognosis Increasing ADC Transient increase in BV Good response Low ADC- Malignant Elevated BV or Ve Recurrent tumor ALLERGIC FUNGAL SINUSITIS