e Ed E e Ed E-127 KNOWING WHAT

e. Ed. E#: e. Ed. E-127 KNOWING WHAT, WHEN AND HOW TO INTERPRET: GUIDE TO IMAGING SALIVARY GLAND PATHOLOGY Umar Chaudhry+, Saba Hamid+, Umber Shafique+, Joan Maley+, Bruno Polliceni+, Henry Hoffmman* + Section of Neuroradiology, Department of Diagnostic Radiology, Univeristy of Iowa Hospitals and Clinics. * Department of Otolaryngology, University of Iowa Hospitals and Clinics.

OUTLINE • INTRODUCTION • MODALITIES AVAILABLE • INDIVIDUAL MODALITIES • INDICATIONS • PROTOCOL • ADVANTAGES • DISADVATAGES • PICTORIAL EXAMPLES • PEARLS “ The years teach much which the days never knew ” Ralph Waldo Emerson

INTRODUCTION • Salivary gland pathology is one the most variable amongst the organ system • Wide variety of imaging modalities used • It becomes confusing to determine the most optimum modality when encountered with a clinical scenario • With era of cost effectiveness, ever increasing patient awareness, and extensive clinician interactions, the expectations from a radiologist have increased • This presentation is intended to be a quick reference guide and refresher for various tools in our arsenal when dealing with such scenarios

MODALITIES • Computed Tomography • Magnetic resonance imaging • Ultrasound • Conventional Sialography • Nuclear imaging

COMPUTED TOMOGRAPHY (CT)

INDICATIONS: Optimal: - Inflammatory pathologies, infection Obstructive pathologies: stones Occasional: - CT sialography, ductal pathology Masses Post radiation

PROTOCOL - Multidetector CT (MDCT) - k. VP 80 -120 k. VP - Dose reduction techniques: - Thyroid bismuth shields Automated dose reduction Lower k. V Studies showed no significant diagnostic difference between 80 and 120 k. V protocols - Inflammatory conditions, abscess usually IV contrast - Stones - Non contrast

ADVANTAGES - Quick - Readily available - Gross anatomical detail of surrounding structuresextent of inflammation - High sensitivity for Stones/calcifications - 3 D reconstructions: CT Sialography

DISADVANTAGES - Ionizing radiation- pregnant and children Not ideal for tumors as higher detail from MRI Perineural spread in malignancies is difficult Poor ductal anatomical detail with standard CT

Inflammation of left parotid gland

A CASE OF A LEFT PAROTID GLAND TUMOR – PLEOMORPHIC ADENOMA WITH SPILLING, STRUCTURAL DETAILS AND MARGINS NOT AS CLEAR AS WITH MRI

RIGHT SUBMANDIBULAR GLAND DUCT STONE (RECTANGLE) WITH DILATED DUCT (CIRCLE)

PEARLS - CT - Acute conditions in adult patients Inflammation Stones questioned With radiation awareness, consider dose modulation

MAGNETIC RESONANCE IMAGING (MRI)

INDICATIONS Salivary gland masses Systemic conditions, usually non acute Ductal anatomy - Sialography

PROTOCOL - For masses or major salivary glands, usually gadolinium based contrast - Varies from one institution to the other - Our institution protocol - 3 plane localizer Coronal and axial T 2 Axial T 1 Diffusion 3 plane post -contrast T 1 images

EXAMPLE OF SCAN VOLUMES FOR PAROTID GLAND

MRI SIALOGRAPHY - Relies on heavily T 2 weighted sequences and water property of saliva - Side of abnormality and duct included in the scan volume for MR Sialography - Protocol also varies from institution to institution - 2 D pulse sequences used traditionally - Projection and Maximum Intensity projections for Sialography - 2 D pulse sequence techniques to increase quality of images include - Projection technique by using a microscopic coil improving the quality of the images obtained with larger coils Recently 3 D pulse sequences utilized for more post processing options

ADVANTAGES - No radiation Non invasive Excellent gland detail Tumor characterization, using signal intensity, margins, pattern of spread, diffusion coefficients Facial nerve characterization in parotid lesions

DISADVANTAGES - Time consuming - not ideal for acute settings Expensive Limited field of view More susceptible to artifacts Ductal detail needs careful optimization, otherwise may be confounded by vessels etc.

PEARLS - Non acute - Ideal for major salivary gland masses and systemic conditions such as Sjogren characterization - Spread of malignancies- perineural tumor spread - New techniques such as dynamic contrast high potential - After optimization ductal details acquired non invasively

PLEOMORPHIC ADENOMA ON MRI T 2 - HIGH T 1 - LOW POST CONTRAST HOMOGENOUS

MALIGNANT PAROTID TUMOR WITH PERINEURAL TUMOR SPREAD (CIRCLE)

ULTRASOUND

INDICATIONS: - Acute inflammations Pediatric and pregnant population Image guided procedures Initial screening of major salivary gland mass

PROTOCOL - High frequency linear probes - 7. 5 -12 MHz - Color doppler - Real time imaging Figure: Example of color doppler on a parotid mass

ADVANTAGES - No ionizing radiations Quick Real time imaging- image guided procedures Less expensive and more readily available than MRI

DISADVANTAGES - - Operator dependence Ducts especially Parotid duct not well seen unless largely dilated Limited field of view- Deeper pathologies such as parapharyngeal space lesions and deep lobes of parotid glands not well see Less specific characterization of masses as compared to MRI

PAROTID PLEOMORPHIC ADENOMA Normal parotid parenchyma is more echogenic and homogenous

PEARLS Children and pregnant patients Initial screening for acute conditions such as infections Image guided procedures One of the most cost effective modalities in cross sectional imaging

CONVENTIONAL SIALOGRAPHY

INDICATIONS: - Obstructive and ductal salivary gland pathology Preoperative exam before sialendoscopy

PROTOCOL - Fluoroscopy- real time imaging Usually Kv range close to 70 k. V Iodine based contrast directly instilled into major salivary gland ducts Images in two planes Ductal and glandular phase Stimulation for glandular phase - Lime/candy

Sialography- The Procedure SIALOGRAPHY -TECHNIQUE • Basic principle: Instilling radio-opaque contrast directly into the duct opening Salivary Gland Stenson’s duct Canula Syringe containing contrast Sialography can be performed with or without digital subtraction - digital subtraction favored, as it removes the confounding bone opacities

ADVANTAGES - Resurgence due to preoperative insight before minimally invasive ENT procedures Ductal resolution and detail superior to many other modalities Lower dose than CT sialography

DISADVANTAGES - Invasive Ionizing radiation Expertize required

Common pathologies-a sialographic perspective SIALOGRAPHY IN SIALOLITHIASIS Filling defects seen in Stenson’s duct, with dilated ducts upstream from the obstruction

PEARLS - Not to be overlooked and seeing a resurgence due to new minimally invasive techniques in ENT Ductal pathology well seen Usually requires close collaboration with ENT

NUCLEAR MEDICINE

INDICATIONS: - Long term dysfunction/sialadenitis - Metastatic workup

PROTOCOL - Salivary scintigraphy - Tc-99 m Planar and SPECT imaging Mainly for long term dysfunction after radioiodine PET - Fluoro-deoxy glucose for metastatic workup and distant lesions

ADVANTAGES - Functional information Distant metastatic lesions

DISADVANTAGES - Non-specific for salivary gland tumors Non acute pathologies only Limited use Cost and availabillity

PET-FDG SCAN IN METASTATIC SALIVARY GLAND TUMOR: NECK NODE AND RIGHT LUNG NODULE

PEARLS - Overall limited role - Chronic sialadenitis after radioactive iodine- Tc-99 m scintigraphy - FDG-PET is non specific, can be used for distant metastasis after tissue diagnosis

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