GLOBAL PI-RADS STANDARIZATION: Appendix III

APPENDIX III: Lexicon

ABNORMALITY

Focal abnormality

Focus

Index Lesion

Lesion

Mass

Nodule

Non-focal abnormality

Diffuse

Multifocal

Regional

SHAPE

Round

Oval

Lenticular

Lobulated

Water-drop-shaped

Wedge-shaped

Linear

Irregular

MARGINS

Circumscribed

Non-circumscribed

Indistinct

Obscured

Irregular

Spiculated

Encapsulated

Organized chaos

Erased charcoal sign

MR IMAGING SIGNAL CHARACTERISTICS

Hyperintense

T2 Hyperintensity

Isointense

Hypointense

Markedly hypointense

T2 hypointensity

Restricted diffusion

Diffusion-weighted hyperintensity

Apparent Diffusion Coefficient (ADC)

ADC Map

ADC Hyperintense

ADC Isointense

ADC Hypointense

b-value

Dynamic contrast enhanced DCE Wash-in

DCE Wash-out

Pharmacodynamic analysis PD curves

Time vs. signal intensity curve

Enhancement kinetic curve

ENHANCEMENT PATTERNS

Early phase wash-in

Delayed phase

Persistent delayed phase Type 1 curve

Plateau delayed phase Type 2 curve

Washout delayed phase Type 3 curve

Positive DCE

Negative DCE

ANATOMICAL TERMS

Prostate: Regional Parts

Base of prostate

Mid prostate

Apex of prostate

Peripheral zone

Transition zone

Central zone

Anterior fibromuscular stroma

Prostate: Sectors

Prostate “capsule”

Prostate pseudocapsule

Seminal vesicle

Neurovascular bundle of prostate NVB

Right neurovascular bundle

Left neurovascular bundle

Vans deferens

Verumontanum

Neck of urinary bladder

Urethra: Prostatic

Urethra: Membranous

External urethral sphincter

Periprostatic compartment

Rectoprostatic compartment Rectoprostatic angle

Extraprostatic

Prostate –seminal vesicle angle

STAGING TERMS

Abuts “capsule” of prostate

Bulges “capsule” of prostate

Mass effect on surrounding tissue

Invasion

Invasion: “Capsule”

Extra-capsular extension ECE

Extraprostatic extension EPE

Extraglandular extension

Invasion: Pseudocapsule

Invasion: Anterior fibromuscular stroma   Invasion: Prostate -seminal vesicle angle   Invasion: Seminal vesicle   Seminal vesicle invasion SVI                         Invasion: Neck of urinary bladder   Invasion: Membranous urethra   Invasion: Periprostatic, extraprostatic   Invasion: Neurovascular bundle of prostate               Invasion: External urethral sphincter

MRI CHARACTERISTICS OF ADDITIONAL PATHOLOGIC STATES

BPH nodule

Hypertrophy of median lobe of prostate

Cyst

Hematoma – Hemorrhage

Calcification

Localized at a focus, central point or locus

Localized finding distinct from neighboring tissues,nota three– dimensional space occupying structure

Lesion identified on MRI with the highest PIRADS AssessmentCategory. If the highest PIRADS Assessment Category is assigned to two or more lesions, the index/dominant lesion should be one that shows EPE or is largest. Also known as dominant lesion

A localized pathological or traumatic structural change, damage, deformity, or discontinuity of tissue, organ, or body part

A three dimensional space occupyingstructure resulting from an accumulation of neoplastic cells, inflammatory cells, or cystic changes

A small lump, swelling or collection of tissue

Not localized to a single focus

Widely spread; not localized or confined; distributed over multiple areas, may or may not extend incontiguity, does not conform to anatomical boundaries

Multiple foci distinct from neighboring tissues

Conforming to prostate sector, sextant, zone, or lobe; abnormal signal other than a mass involving a large volume of prostatic tissue

The shape of a circle or sphere

The shape of either an oval or an ellipse

Having the shape of a double-convex lens, crescentic

Composed of lobules with undulating contour

Having the shape of a tear or drop of water; it differs from an oval because one end is clearly larger than the other

Having the shape of a wedge, pie, or V-shaped

In a line or band-like in shape

Lacking symmetry or evenness

Well defined

Ill-defined

Blurred

Not clearly seen or easily distinguished

Uneven

Radiating lines extending from the margin of a mass

Bounded bya distinct, uniform, smooth low-signal line (BPH nodule)

Heterogeneous mass in transition zone with circumscribed margins, encapsulated (BPH nodule)

Blurred margins as if smudged, smeared with a finger; refers to appearance of a homogeneously T2 low-signal lesion in the transition zone of the prostate with indistinct margins (prostate cancer)

Having higher signal intensity (more intense, brighter) on MRI than background prostate tissue or reference tissue/structure

Having higher signal intensity (more intense, brighter) on T2– weighted imaging

Having the same intensity asa reference tissue/structure to which it is compared; intensity at MRI that is identical or nearly identical to that of a background prostate

Having less intensity (darker) than background prostate tissue or reference tissue/structure

Signal intensity lower than expected for normal or abnormal tissue of the reference type, e.g. when involved with calcification or blood or gas

Having lower signal intensity (less intense, darker) on T2– weighted imaging

Limited, primarily by cell membrane boundaries, random Brownian motion of water molecules within the voxel; having higher signal intensity than peripheral zone or transition zone prostate on DW images acquired or calculated at b values >1400 accompanied by lowered ADC values. Synonymous with “impeded” diffusion

Having higher signal intensity, not attributable to T2 shine– through, than background prostate on DW images

A measure of the degree of motion of water molecules in tissues. It is determined by calculating the signal loss in data obtained with different b-values and is expressed in units of mm2/sec or µm2/sec

A display of ADC values for each voxel in an image

Having higher signal intensity (more intense, brighter) than background tissue on ADC map

Intensity that is identical or identical to that of background tissue on ADC map

Having lower intensity (darker) than a reference background tissue on ADC map

A meaure of the strength and duration of the diffusion gradients that determines the sensitivity ofa DWI sequence to diffusion

Early arterial phase of enhancement;a period of time to allow contrast agent to arrive in the tissue

Later venous phase, de-enhancement, reduction of signal following enhancement; a period of time to allow contrast agent to clear the tissue

Method of quantifying tissue contrast media concentration changes to calculate time constants for the rate of wash-in and wash-out

Graph plotting tissue intensity change (y axis) over time (x axis)

Enhancement kinetic curve is a graphical representation of tissue enhancement where signal intensity of tissue is plotted asa function of time

Signal intensity characteristic early after contrast agent administration; wash-in phase corresponding to contrast arrival in the prostate

Signal intensity characteristic following its initial (early) rise after contrast material administration

Continued increase of signal intensity over time

Signal intensity does not change over time after its initial rise, flat; plateau refers to signal that varies <10% from the peak signal over the duration of the DCE MRI

Signal intensity decreases after its highest point after its initial rise

Focal, early enhancement corresponding to a focal peripheral zone or transition zone lesion on T2 and/or DWI MRI

Lack of early enhancement, Diffuse enhancement not corresponding to a focal lesion on T2 and/or DWI MRI, Focal enhancement corresponding toa BPH lesion

The prostate is divided from superior to inferior into three regional parts: the base, the midgland, and the apex.

The upper 1/3 of the prostate just below the urinary bladder.

The middle 1/3 of the prostate that includes verumontanum in the mid prostatic urethra; midgland

The lower 1/3 of the prostate

Covers the outer posterior, lateral, and apex regions of the prostate; makes up most of the apex of the prostate

Tissue around the urethra that is separated from the peripheral zone by the “surgical capsule” delineated as a low signal line on T2 weighted MRI; it is the site of most BPH

Tissue surrounding the ejaculatory ducts posterior and superior, from the base of the prostate to the verumontanum; it has the shape of an inverted cone with its base oriented towards the base of the gland; contains more stroma than glandular tissue

Located anteriorly and contains smooth muscle, which mixes with periurethral muscle fibers at the bladder neck; contains no glandular tissue

Anatomical regions defined for the purpose of prostate targeting during interventions, may include multiple constitutional and regional parts of the prostate. Thirty-six sectors for standardized MRI prostate localization reporting are identified, with addition of seminal vesicles and membranous urethra. Each traditional prostate sextant is sub– divided into six sectors, to include: the anterior fibromuscular stroma, the transition zone anterior and posterior sectors, the peripheral zone anterior, lateral, and medial sectors. The anterior and posterior sectors are defined bya line bisecting the prostate into the anterior and posterior halves. Diagram

Histologically, there is no distinct capsule that surrounds the prostate, however historically the “capsule” has been defined as an outer band of the prostatic fibromuscular stroma blending with endopelvic fascia that may be visible on imaging as a distinct thin layer of tissue surrounding or partially surrounding the peripheral zone.

Imaging appearance of a thin “capsule” around transition zone when no true capsule is present at histological evaluation. The junction of the transition and peripheral zones marked bya visible hypointense linear boundary, which is often referred to as the prostate “pseudocapsule” or “surgical capsule”.

One of the two paired glands in the male genitourinary system, posterior to the bladder and superior to the prostate gland, that produces fructose-rich seminal fluid which is a component of semen. These glands join the ipsilateral ductus (vas) deferens to form the ejaculatory duct at the base of the prostate.

Nerve fibers from the lumbar sympathetic chain extend inferiorly to the pelvis along the iliac arteries and intermix with parasympathetic nerve fibers branching off S2 to S4. The mixed nerve bundles run posterior to the bladder, seminal vesicles, and prostate as the “pelvic plexus”. The cavernous nerve arises from the pelvic plexus and runs along the posterolateral aspect of the prostate on each side. Arterial and venous vessels accompany the cavernous nerve, and together these structures form the neurovascular bundles which are best visualized on MR imaging at 5 and 7 o’clock position. At the apex and the base of the prostate, the bundles send penetrating branches through the “capsule”, providinga potential route for extraprostatic tumor spread.

Located at 7 o’clock postero-lateral position.

Located at 5 o’clock postero-lateral position.

The excretory duct of the testes that carries spermatozoa; it rises from the scrotum and joins the seminal vesicles to form the ejaculatory duct, which opens into the mid prostatic urethra at the level of the verumontanum.

The verumontanum (urethral crest formed by an elevation of the mucous membrane and its subjacent tissue) is an elongated ridge on the posterior wall f the mid prostatic urethra at the site of ejaculatory ducts opening into the prostatic urethra.

The inferior portion of the urinary bladder which is formed as the walls of the bladder converge and become contiguous with the proximal urethra.

The proximal prostatic urethra extends from the bladder neck at the base of the prostate to verumontanum in the mid prostate. The distal prostatic urethra extends from the verumontanum to the membranous urethra and contains striated muscle of the urethral sphincter.

The membranous segment of the urethra is located between the apex of the prostate and the bulb of the corpus spongiosum, extending through the urogenital diaphragm.

Surrounds the whole length of the membranous portion of the urethra and is enclosed in the fascia of the urogenital diaphragm.

Space surrounding the prostate

Space between the prostate and the rectum

Pertaining to an area outside the prostate

The plane or space between the prostate base and the seminal vesicle, normally filled with fatty tissue and neurovascular bundle of prostate.

Tumor touches the “capsule”

Convex contour of the “capsule” Bulging prostatic contour over a suspicious lesion: Focal, spiculated (extraprostatic tumor) Broad-base of contact (at least 25% of tumor contact with the capsule) Tumor-capsule abutment of greater than 1 cm Lenticular tumor at prostate apex extending along the urethra below the apex.

Compression of the tissue around the mass, or displacement tissue of adjacent tissues or structures, or obliteration of the tissue planes by an infiltrating mass

Tumor extension across anatomical boundary; may relate to tumor extension within the gland, i.e. across regional parts of the prostate, or outside the gland, across the “capsule” (extracapsular extension of tumor, extraprostatic extension of tumor, extraglandular extension of tumor).

Tumor involvement of the “capsule” or extension across the “capsule” with indistinct, blurred or irregular margin

Retraction of the capsule

Breach of the capsule

Direct tumor extension through the “capsule” Obliteration of the rectoprostatic angle

Tumor involvement of pseudocapsule with indistinct margin

Tumor involvement of anterior fibromuscular stroma with indistinct margin

Tumor extends into the space between the prostate base and the seminal vesicle

Tumor extension into seminal vesicle

There are 3 types:

1. Tumor extension along the ejaculatory ducts into the seminal vesicle above the base of the prostate; focal T2 hypointense signal within and/or along the seminal vesicle; enlargement and T2 hypointensity within the lumen of seminal vesicle. Restricted diffusion within the lumen of seminal vesicle. Enhancement along or within the lumen of seminal vesicle. Obliteration of the prostate-seminal vesicle angle 2. Direct extra-glandular tumor extension from the base of the prostate into and around the seminal vesicle. 3. Metachronous tumor deposit -separate focal T2 hypointense signal, enhancing mass in distal seminal vesicle

Tumor extension along the prostatic urethra to involve the bladder neck

Tumor extension along the prostatic urethra to involve the membranous urethra

Tumor extension outside the prostate

Tumor extension into the neurovascular bundle of the prostate Asymmetry, enlargement or direct tumor involvement of the neurovascular bundles Assess the recto-prostatic angles (right and left): 1. Asymmetry – abnormal one is either obliterated or flattened. 2. Fat in the angle – infiltrated (individual elements cannot be identified or separated) clean (individual elements are visible ) 3. Direct tumor extension

Tumor extension into the external urethral sphincter Loss of the normal low signal of the sphincter, discontinuity of the circular contour of the sphincter

A round/oval mass with a well-defined T2 hypointense margin; encapsulated mass or “organized chaos” found in the transition zone or extruded from the transition zone into the peripheral zone

Increase in the volume of the median lobe of the prostate with mass-effect or protrusion into the bladder and stretching the urethra

A circumscribed T2 hyperintense fluid containing sac-like structure

T1 hyperintense collection or focus

Focus of markedly hypointense signal on all MRI sequences