Radiology - imaging pancreatic solid lesion benign and malignant 1 adenocarcinoma and it's variant 2 acinar cell carcinoma, medullary carcinoma,hepatoid variant, signet cell carcinoma of pancrease,pnet it type function and non functional,

Radiology - imaging pancreatic solid lesion benign and malignant , pathognomic imaging findings ct mri usg, pathophysiology, differentiating features form other pancreatic lesion 1 adenocarcinoma and it's variant 2 acinar cell carcinoma, medullary carcinoma,hepatoid variant, signet cell carcinoma of pancrease,pnet it type function and non functional, mets ,hyperenhacning pancreatic tumour dd ,spn, mcn,scn, ipnm and it's malignant transformation which types , pancreatic ct protocols and mri protocols, associated syndrome and sign ,paraneoplastic syndrome, ectopic splenic tissue in pancreas, pancreas paraganglinoma , mass forming pancreatitis, groove pancreatitis, aip , resectibility criteria, treatment with Radiological aspect ,dual energy CT in pancrease, split bolus in pancreas, iodine mapping in pancreas pathology,

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Here is the complete, integrated radiology reference on pancreatic solid lesions. Given the breadth of the topic I've organized everything into 17 sections. Let me know if you'd like any section expanded further (e.g., EUS, staging tables, radiomics, specific case scenarios, or treatment planning CT for radiation therapy).

Pancreatic Solid Lesions: Comprehensive Radiology Reference

SECTION 1: PANCREATIC CT AND MRI PROTOCOLS

Dedicated Pancreatic CT (MDCT)

The gold standard is multiphasic contrast-enhanced MDCT using water as oral contrast (hydro-CT). Four phases are used:

Phase	Timing (post-injection)	Primary Purpose
Non-contrast	Baseline	Calcification, hemorrhage, baseline density
Pancreatic parenchymal phase (late arterial)	40-50 sec	PDAC detection (max parenchyma vs. hypoenhancing tumor); hyperenhancing PNETs; vascular anatomy
Portal venous phase	65-70 sec	Liver metastases, venous invasion, lymphadenopathy
Delayed phase	3-5 min	PDAC desmoplastic delayed enhancement; AIP halo; SPN progressive enhancement

Slice thickness: 0.6-1.0 mm for multiplanar reconstruction (coronal, sagittal, curved planar)
Vessel assessment: detailed thin-section reconstructions of SMA, celiac trunk, SMV, portal vein, CHA
Water as oral contrast prevents masking of hyperdense lesions or vascular blush

MRI Protocol

Sequence	Key Role
T1W fat-saturated (pre-contrast)	Pancreas is normally T1 bright (zymogen granules); PDAC is T1 dark - single best sequence for detection
T2W TSE/HASTE	Cystic lesions, ductal dilation, splenic signal matching (IPAS); SPN capsule
DWI (b=0, 500, 800-1000)	Restricted diffusion in malignancy; ADC maps
Dynamic post-Gd (arterial, venous, delayed)	Enhancement kinetics: hyper = PNET/IPAS; hypo = PDAC; progressive = fibrous
MRCP	Ductal anatomy; double duct sign; BD-IPMN communication; branch duct disease
In/out-of-phase (GRE)	Fat content in SPN, lipid lesions

The most sensitive MRI sequence for pancreatic cancer is T1W fat-saturated immediate post-gadolinium SGE, which shows the hypoenhancing tumor against the brightly enhancing normal parenchyma (Yamada's Gastroenterology, p. 2783).

Split Bolus Technique

Principle: Two contrast boluses injected with a ~75-90 second delay, then one CT acquisition that captures two enhancement phases simultaneously:

First bolus provides portal venous phase liver enhancement
Second bolus provides pancreatic parenchymal phase enhancement
One acquisition = two phases = reduced radiation dose
Particularly useful in young patients, surveillance protocols, dose-reduction settings
Limitation: timing is less precise than dedicated dual-phase; not ideal when maximum quality is needed for staging

SECTION 2: PANCREATIC DUCTAL ADENOCARCINOMA (PDAC)

Pathophysiology

PDAC arises from ductal epithelium via a PanIN (pancreatic intraepithelial neoplasia) → PDAC sequence, driven by KRAS mutation (>90%), TP53, SMAD4, CDKN2A. The hallmark is abundant desmoplastic stroma (fibrous tissue > tumor cells) - this produces the imaging signatures of hypoenhancement and delayed enhancement, impedes drug delivery, and confers the aggressive biology. Early spread is perivascular, perineural, and lymphatic. At diagnosis, only 10-20% have resectable disease; 5-year survival ~5-12% (Grainger & Allison, p. 695).

Imaging Findings

Ultrasound:

Poorly marginated hypoechoic solid mass
Dilated CBD and/or pancreatic duct (double duct sign in head lesions)
Loss of normal lobular architecture; parenchymal atrophy upstream
Doppler: perivascular encasement in advanced disease
Limitation: body/tail often obscured by bowel gas; insufficient for staging

CT (Pancreatic Parenchymal Phase):

Pathognomonic: poorly defined hypoenhancing (hypodense) mass against the avidly enhancing normal parenchyma
Tumor HU typically < 40 vs. normal parenchyma > 80-100 HU in pancreatic phase
Location: ~70% pancreatic head/uncinate; 20% body; 10% tail
Upstream pancreatic ductal dilation with parenchymal atrophy distal to obstruction
Delayed enhancement (3-5 min phase): tumor enhances more due to desmoplastic stroma
Isoattenuating PDAC (~10-15%): no visible mass but indirect signs present (duct cutoff, atrophy, contour deformity)
Vascular invasion: encasement, irregularity, or occlusion of SMA, celiac, SMV, portal vein

CT Signs:

Double duct sign - simultaneous CBD + MPD dilation (head/periampullary tumors) - pathognomonic for head PDAC
Duct cutoff sign - abrupt termination of dilated MPD at tumor
Upstream atrophy sign - parenchymal atrophy proximal to obstructed duct
Teardrop sign - flattening/distortion of SMV by adjacent tumor contact
Perivascular cuffing - soft tissue encasing mesenteric vessels

MRI:

T1W fat-sat (pre-contrast): markedly hypointense vs. bright normal pancreas - the most sensitive sequence
T2W: mildly hyperintense or isointense; desmoplastic stroma = T2 hypointense areas
DWI: restricted diffusion (ADC ~1.0-1.4 × 10⁻³ mm²/s)
Post-Gd arterial/venous: hypoenhancing (same as CT)
Post-Gd delayed: progressive enhancement of desmoplastic stroma
MRCP: double duct sign, upstream MPD dilation, duct cutoff, stenosis

Differentiating PDAC from Mimics:

Feature	PDAC	Mass-forming Pancreatitis	AIP	PNET
Enhancement	Hypo, delayed	Iso/hypo, earlier	Delayed + halo	Arterial hyper
MPD involvement	Abrupt cutoff, upstream dilation	Gradual, irregular	Long stricture, no upstream dilation	Displacement only
Vascular invasion	Common	Uncommon	Uncommon	Encasement (large NF-PNET)
Upstream atrophy	Yes	Not always	No (sausage shape)	No
IgG4	Negative	Negative	Elevated (Type I)	Negative
Steroid response	No	No	Yes (dramatic)	No
CA 19-9	High	Mild	Mild/negative	Variable

SECTION 3: VARIANTS OF PANCREATIC CARCINOMA

1. Acinar Cell Carcinoma (ACC)

~1-2% of pancreatic malignancies; arises from acinar cells
Unlike PDAC: typically large, well-circumscribed, exophytic mass
CT: heterogeneous, partially cystic or necrotic; may show arterial hyperenhancement
Crucially: often lacks upstream ductal dilation (no desmoplastic duct obstruction) - key differentiator
Liver metastases common at presentation
Paraneoplastic - Lipase Hypersecretion Syndrome: subcutaneous fat necrosis (panniculitis), polyarthritis, eosinophilia - pathognomonic for ACC
AFP may be elevated
Prognosis better than PDAC but still aggressive

2. Medullary Carcinoma

Rare variant; syncytial growth pattern with prominent lymphocytic infiltrate (resembling medullary carcinoma of breast/colon)
MSI-H (microsatellite instability-high) and KRAS wild-type - critical molecular feature
Imaging: tends to be better-defined, less desmoplastic than conventional PDAC; may be less hypoenhancing; geographic pushing margins
Clinical significance: responds to immune checkpoint inhibitors (pembrolizumab) due to MSI-H - must not miss this diagnosis

3. Hepatoid Variant of Pancreatic Carcinoma

Extremely rare; morphologically resembles hepatocellular carcinoma (HCC)
Produces AFP (alpha-fetoprotein) - paraneoplastic marker
Imaging: may show arterial hyperenhancement followed by washout pattern, mimicking HCC metastases
Key differentiator from metastatic HCC: AFP elevation + pancreatic primary + no cirrhosis/liver disease context
High malignant potential; often diagnosed late

4. Signet Ring Cell Carcinoma of the Pancreas

Very rare as a primary; must exclude metastatic signet ring carcinoma from stomach, colon, or breast first
Imaging: diffusely infiltrative, poorly defined, hypodense; may cause diffuse pancreatic enlargement mimicking AIP or lymphoma
Peritoneal dissemination common at presentation
Look for co-existing gastric linitis plastica (check stomach carefully on CT/MRI)
Very poor prognosis

SECTION 4: PANCREATIC NEUROENDOCRINE TUMORS (PNETs)

WHO 2017 Classification

Grade	Ki-67	Mitoses/10 HPF	Behavior
NET G1	<3%	<2	Benign/low malignant
NET G2	3-20%	2-20	Intermediate
NET G3	>20%	>20	Malignant (well-differentiated)
NEC (large/small cell)	>20%	>20	Highly malignant

10-20% associated with genetic syndromes: MEN-1 (most common), VHL, tuberous sclerosis, NF-1 (Yamada's, p. 675).

Functional PNETs - Types and Syndromes

Tumor	Hormone	Clinical Syndrome	Key Features
Insulinoma	Insulin	Whipple's triad: fasting hypoglycemia, neuroglycopenic symptoms, relief with glucose	Commonest PNET; 90% benign; small (<2 cm); solitary; intrapancreatic; hard to find on CT (occult in ~30%)
Gastrinoma	Gastrin	Zollinger-Ellison: refractory peptic ulcers, secretory diarrhea	60-90% malignant; "Gastrinoma triangle" location; 30-50% in MEN-1
Glucagonoma	Glucagon	4D syndrome: Dermatitis (necrolytic migratory erythema), Diabetes, DVT, Depression	70-80% malignant; large; body/tail
VIPoma	VIP	WDHA/Verner-Morrison: Watery Diarrhea, Hypokalemia, Achlorhydria	50-80% malignant
Somatostatinoma	Somatostatin	Diabetes, cholelithiasis, steatorrhea, hypochlorhydria	Periampullary; NF-1 association
ACTHoma	ACTH	Ectopic Cushing's syndrome	PNET or NEC

Gastrinoma triangle (boundaries): (1) junction cystic duct/CBD, (2) junction duodenum 2nd/3rd portion, (3) neck of pancreas. Gastrinomas may be extrapancreatic (duodenal wall - common!).

Imaging of PNETs

CT:

Small PNETs: arterial/pancreatic phase hyperenhancement - the hallmark (hypervascular)
Larger NF-PNETs: heterogeneous, cystic degeneration, necrosis, calcification (~20%); may be less hypervascular
Detected best on pancreatic parenchymal phase CT
On portal venous phase: can become iso/hypoattenuating (wash-out pattern)
Insulinoma: small, isoattenuating on non-contrast; bright arterial blush; EUS required if CT negative
Liver metastases from PNET: hypervascular (arterial blush) - distinguish from hypovascular PDAC mets

MRI:

T1W: hypointense
T2W: mildly to moderately hyperintense (vs. PDAC T2 iso/hypointense due to fibrosis) - key differential
Post-Gd: arterial hyperenhancement (discriminating from PDAC)
DWI: restricted diffusion

Nuclear Medicine:

Ga-68 DOTATATE PET-CT (somatostatin receptor PET): high sensitivity for SSTR2-expressing tumors; superior to CT for occult primary, staging, and metastases
Insulinoma: SSTR2-negative → Ga-68 DOTATATE may be negative; use EUS or arterial calcium stimulation test or 18F-DOPA PET
FDG-PET: positive in poorly differentiated NEC (G3/NEC); inversely correlates with SSTR expression ("flip-flop" phenomenon)

Diagnostic and treatment pathway for suspected PNETs (Current Surgical Therapy 14e)

Non-Functional PNETs (NF-PNETs)

60-90% of all PNETs; detected incidentally on cross-sectional imaging
Presentation: abdominal pain, mass effect, biliary obstruction (head lesions), or incidental finding
Imaging: same hyperenhancing pattern but larger at discovery; liver mets at presentation ~40%
Small incidental NF-PNETs <2 cm, no worrisome features: active surveillance is acceptable

SECTION 5: HYPERENHANCING PANCREATIC TUMORS - DIFFERENTIAL DIAGNOSIS

Diagnosis	Key Differentiating Features
PNET	Most common; T2 bright; Ga-68 DOTATATE positive; hormonal syndromes
Metastasis (RCC)	Known renal cell carcinoma history; solitary or multiple; check kidneys; arterial blush
Acinar cell carcinoma	Large, heterogeneous; lipase hypersecretion syndrome
Solid pseudopapillary neoplasm	Young women; mixed solid-cystic; T1 hemorrhage; encapsulated
Intrapancreatic accessory spleen	Exact density/signal match with spleen; pancreatic tail; SPIO/sulfur colloid scan confirms; DOTATATE negative
Pancreatic paraganglioma	T2 "light bulb" bright; catecholamine excess; MIBG positive
Hepatoid carcinoma	AFP elevated; arterial enhancement + washout
PEComa	Fat-containing; tuberous sclerosis; TFE3 fusion
Angiosarcoma	Extremely rare; aggressive vascular

SECTION 6: SOLID PSEUDOPAPILLARY NEOPLASM (SPN / Frantz Tumor)

<3% of pancreatic neoplasms; young women (20s-30s), F:M = 10:1; low malignant potential (~15% metastatic potential)
Body/tail predominance; typically large (>4 cm) at presentation
Mutations: CTNNB1 (beta-catenin) - nuclear accumulation on immunohistochemistry

CT:

Well-encapsulated mixed solid-cystic mass with thick fibrous capsule
Peripheral solid component + central cystic/necrotic/hemorrhagic areas
Capsule: eggshell calcification (characteristic when present)
Heterogeneous enhancement of solid components; capsule enhances

MRI:

T1W: hyperintense foci (intratumoral hemorrhage) - the hallmark on MRI
T2W: heterogeneous; fibrous capsule = T2 hypointense rim
In/out-of-phase: no signal drop (no intracellular fat)
Post-Gd: progressive solid component enhancement
DWI: restricted diffusion in solid parts
The triad of T1 hyperintense hemorrhage + T2 hypointense capsule + young woman = near-diagnostic

SECTION 7: MUCINOUS CYSTIC NEOPLASM (MCN)

Exclusively in women (>95%); body/tail predominance
Does NOT communicate with the main pancreatic duct - key differentiator from IPMN
Histological hallmark: ovarian-type stroma in the wall
Malignant potential: ~15% (mucinous cystadenocarcinoma)
Cyst fluid: CEA > 192 ng/mL supports mucinous etiology

Imaging:

Unilocular or oligolocular macrocystic mass with thick wall, septa, possible mural nodules
Peripheral eggshell calcification (when present - suggests malignancy in context of MCN)
CT: macrocystic lesion in body/tail, thin-to-thick septations, fluid-filled
MRI T2W: high signal fluid; T1W: proteinaceous content may be T1 bright
Mural nodule + enhancement: worrisome for malignant transformation → resection

Mucinous cystadenoma: macrocystic body/tail mass with thin septations on CT and T2W MRI (Grainger & Allison)

SECTION 8: SEROUS CYSTIC NEOPLASM (SCN)

Almost always benign (serous cystadenocarcinoma exceedingly rare)
More common in older women (7th decade); pancreatic head
VHL syndrome association (pancreatic cysts + SCN)

Pathognomonic features:

Microcystic (honeycomb) pattern: innumerable small cysts (<1-2 cm each)
Central stellate scar with sunburst/radiating calcification (30-40%) - pathognomonic
CT: lobulated mass, hypodense microcysts, central enhancing scar
MRI T2W: markedly hyperintense microcysts clustered around central scar; septations enhance
Macrocystic (oligocystic) variant: larger cysts; can mimic MCN or pseudocyst - diagnostic challenge
No mural nodules; no ductal communication

Serous cystadenoma: microcystic mass with enhancing central scar, no solid nodule (Grainger & Allison)

SECTION 9: IPMN - INTRADUCTAL PAPILLARY MUCINOUS NEOPLASM

Three Types (Grainger & Allison, p. 706)

Type	Features	Malignancy Risk
Main duct (MD-IPMN)	Diffuse/segmental MPD dilation >5 mm; mucin from patulous ampulla ("fish mouth" ampulla endoscopically); no mass	57-92%
Branch duct (BD-IPMN)	Sac-like cyst communicating with MPD; grape-cluster cysts; no MPD dilation	15-25%
Mixed type	Both MD + BD involvement	~MD risk

MRCP: ideal for showing MPD communication (MinIP reconstructions; grape-like cluster = BD-IPMN)
CT/MRI have similar diagnostic performance for malignant vs. benign IPMN

Malignant Transformation - Imaging Warning Signs (Fukuoka Guidelines)

"Worrisome features" (→ EUS evaluation):

Cyst ≥ 3 cm
Enhancing mural nodule < 5 mm
Thickened/enhanced cyst wall
MPD 5-9 mm caliber
Abrupt MPD change with upstream atrophy
Lymphadenopathy
Rapid growth > 5 mm/2 years
Elevated CA 19-9

"High-risk stigmata" (→ direct surgical resection):

Obstructive jaundice + cystic head lesion
Enhancing mural nodule ≥ 5 mm
MPD ≥ 10 mm caliber

Which IPMN types undergo malignant transformation most?

Main duct type >> Branch duct type in malignant risk
Management: MD-IPMN → surgery; BD-IPMN < 3 cm in asymptomatic patients → serial imaging surveillance

SECTION 10: PANCREATIC METASTASES

Most common primaries: RCC (~70% of pancreatic mets), lung, breast, colon, melanoma
RCC mets: arterial hyperenhancing, multiple, can be solitary; arterial blush; can occur decades after nephrectomy
Lung/colon/breast mets: hypovascular, hypodense
Melanoma mets: may be T1 hyperintense (melanin); can be hypervascular
Key imaging clue: known primary elsewhere + interval appearance + multiple lesions + no upstream ductal changes unless infiltrative
Solitary hypervascular met from RCC can perfectly mimic PNET - clinical history is decisive

SECTION 11: INFLAMMATORY PANCREATIC MASSES

Mass-Forming Pancreatitis (MFP) / Chronic Pancreatitis with Mass

Background of chronic pancreatitis (alcohol, stones, duct changes)
CT: ill-defined, iso/hypodense mass; calcifications common; irregular duct dilation (not abrupt cutoff)
Differentiators from PDAC:
- Gradual/irregular ductal dilation (not abrupt cutoff)
- Calcifications more common
- No vascular encasement
- Pseudocysts may coexist
- Less markedly elevated CA 19-9
- Clinical: chronic alcohol use, recurrent pancreatitis

Groove Pancreatitis (Paraduodenal Pancreatitis)

Fibro-inflammatory process in the groove between the pancreatic head, duodenum, and CBD
Associated with chronic alcohol use and cystic dystrophy of the duodenal wall
CT: sheet-like hypodense soft tissue plaque in the groove; can cause CBD/PD narrowing; no vascular invasion
MRI T2W: cystic spaces within the duodenal wall (Santorini duct cysts) - pathognomonic
MRCP: smooth CBD narrowing; no duct invasion
Key distinguishing features: groove location; T2 duodenal wall cysts; no vascular involvement; alcohol history

Autoimmune Pancreatitis (AIP)

Two types:

Feature	Type I (IgG4-related)	Type II (IDCP)
Serum IgG4	Elevated (×2 ULN = highly specific)	Normal
Extrapancreatic	Yes: bile ducts, kidney, salivary, aorta	No
Histology	LPSP (lymphoplasmacytic sclerosing)	IDCP with GEL (granulocyte epithelial lesion)
Age/Sex	Older males	Younger; IBD association
Focal mass	Less common	Up to 35%

Imaging (Current Surgical Therapy 14e, p. 599; Grainger & Allison, p. 647-648):

Classic diffuse form:

Sausage-shaped diffusely enlarged pancreas with homogeneous attenuation and loss of normal lobulations
Halo/capsule sign: hypoattenuating rim around the pancreas (periductal fibrosis) - characteristic
Little to no visible pancreatic duct
No upstream ductal dilation

Focal form (mimics PDAC in head):

Mass with disproportionately mild upstream ductal dilation relative to mass size (vs. PDAC)
Halo sign still present
No vascular encasement
Long-segment or multiple duct strictures without upstream dilation (MRCP/ERCP)
IgG4-related extrapancreatic signs: biliary strictures (PSC-like), renal hypodense masses, retroperitoneal fibrosis, lymphadenopathy, salivary/lacrimal gland enlargement

CEUS differentiation: AIP = isoenhancement arterial + hyperenhancement late phase vs. PDAC = hypoenhancing throughout.

Steroid response: dramatic, near-complete resolution within weeks - both diagnostic and therapeutic.

AIP: lobulated hypodense head mass mimicking PDAC (left: CT; right: sagittal) (Current Surgical Therapy 14e)

AIP diffuse form: sausage-shaped gland with hypoattenuating peripheral halo on MDCT (Grainger & Allison)

SECTION 12: ECTOPIC SPLENIC TISSUE IN PANCREAS

Intrapancreatic Accessory Spleen (IPAS)

Located in pancreatic tail (>95%); benign; asymptomatic
Most important clinical issue: do not mistake for a hypervascular PNET

Imaging:

CT/MRI: exact density/signal match with splenic parenchyma on every phase - follows splenic enhancement curve perfectly (non-contrast, arterial, portal, delayed all identical to spleen)
MRI T2W: isointense to spleen; in/out-of-phase: no fat drop
SPIO-enhanced MRI: Kupffer cell/RES uptake identical to spleen
Tc-99m sulfur colloid scan or heat-damaged RBC scan: uptake in pancreatic tail mass = spleen - confirmatory
Ga-68 DOTATATE PET: negative in IPAS vs. positive in PNET - most useful differentiator

SECTION 13: PANCREATIC PARAGANGLIOMA

Extremely rare; arises from paraganglia within or adjacent to pancreas
Symptoms: hypertension, headache, palpitations (catecholamine excess) OR incidental
CT: well-defined, arterial hyperenhancing mass; cystic degeneration possible
MRI: T2W markedly hyperintense ("light bulb" sign) - identical to adrenal pheochromocytoma
MIBG scintigraphy: positive in secretory tumors
Ga-68 DOTATATE PET: often positive (SSTR expression)
Biochemistry: elevated plasma/urine metanephrines - differentiates from PNET
Caution: pre-operative alpha-blockade MANDATORY before biopsy or surgery; biopsy without blockade can cause hypertensive crisis

SECTION 14: ASSOCIATED SYNDROMES AND SIGNS

Hereditary/Genetic Syndromes

Syndrome	Pancreatic Lesion
MEN-1	Multiple PNETs (gastrinoma most common), insulinoma; pancreatic involvement in 80%
VHL	Non-functional PNETs (often clear cell); pancreatic cysts (>70%); SCN
Tuberous Sclerosis	PNETs (rare); pancreatic hamartomas
NF-1	Periampullary somatostatinoma; GIST
Familial PDAC (BRCA1/2, PALB2, ATM, CDKN2A)	Elevated PDAC risk; screen with annual EUS/MRI
Peutz-Jeghers (STK11)	High PDAC lifetime risk (~36%)
Lynch syndrome (MSI-H)	Medullary carcinoma variant of PDAC
Hereditary pancreatitis (PRSS1/SPINK1)	Chronic pancreatitis → PDAC (up to 40% lifetime risk)

Radiological Signs

Sign	Lesion	Description
Double duct sign	PDAC (head)	Simultaneous CBD + MPD dilation on MRCP/CT
Duct cutoff sign	PDAC	Abrupt termination of dilated MPD at tumor
Upstream atrophy	Obstructing mass	Parenchymal atrophy proximal to obstruction
Sausage sign	AIP	Diffuse pancreatic enlargement, smooth outline, loss of lobulations
Halo/capsule sign	AIP	Hypoattenuating peripancreatic rim on CT
Teardrop sign	PDAC	Distortion/flattening of SMV profile by tumor
Santorini duct cysts	Groove pancreatitis	Cystic spaces within duodenal wall on T2W MRI
Fish-mouth/patulous ampulla	Main duct IPMN	Mucin extruding from gaping ampulla
Sunburst calcification	SCN	Central scar + radiating calcification on CT
Eggshell calcification	MCN/SPN	Peripheral capsular calcification
Whirlpool sign	SPN/any	Capsule + internal architecture

Paraneoplastic Syndromes

Syndrome	Tumor	Mechanism
Trousseau syndrome (migratory thrombophlebitis)	PDAC (classic)	Tumor procoagulant, mucin
Lipase hypersecretion syndrome (fat necrosis, polyarthritis, eosinophilia)	Acinar cell carcinoma	Circulating lipase/trypsin
Necrolytic migratory erythema (NME)	Glucagonoma	Excess glucagon
Cushing syndrome (ectopic ACTH)	ACTHoma, NEC	Ectopic ACTH secretion
Hypoglycemia	Insulinoma; IGF-2 tumor	Hyperinsulinism
Watery diarrhea/WDHA	VIPoma	VIP excess
Hypercalcemia	PTHrP-secreting PNET	Ectopic PTHrP
Carcinoid syndrome	Serotonin-secreting PNET (rare)	5-HT excess

SECTION 15: RESECTABILITY CRITERIA (NCCN 2024)

Category	Arterial Criteria	Venous Criteria (SMV/PV)
Resectable	No solid tumor contact with SMA, celiac trunk, CHA	No contact OR ≤180° without vein contour irregularity
Borderline Resectable	SMA ≤180° contact; CHA contact without extension to celiac or hepatic bifurcation; celiac ≤180° (body/tail tumors)	>180° contact; OR ≤180° with contour irregularity/thrombosis but vessel is reconstructable
Locally Advanced / Unresectable	SMA or celiac >180° contact; aortic involvement; unreconstructable CHA	SMV/PV occlusion without reconstructable vessel

Key principles:

CT has >90% predictability for unresectable disease
R0 resection predicted by preserved fat plane between tumor and adjacent vessels
Arterial anatomical variants (replaced RHA, replaced LHA) must be documented - changes surgical approach
Post-NAT: NCCN recommends against formal restaging as decrease in tumor size/vascular contact does not reliably equate to pathological downstaging; if no progression → trial dissection

Radiology reporting template essentials (PACT-UK/NCCN):

Tumor size and exact location
Distance/contact with SMA, celiac, CHA, GDA, splenic artery, SMV, PV, splenic vein
Degree of circumferential contact (in degrees) for each vessel
Contour irregularity, thrombosis, teardrop deformity
Arterial variants (replaced RHA arising from SMA - ~20% of patients)
Lymph node status
Distant disease (liver, peritoneum, extra-abdominal)

SECTION 16: DUAL ENERGY CT (DECT) IN PANCREATIC PATHOLOGY

Principles

DECT acquires data at two photon energy levels simultaneously. Key outputs:

Virtual monoenergetic images (VMI): at 40-50 keV, iodine contrast is amplified → better tumor conspicuity
Iodine density maps (iodine material decomposition): quantify iodine concentration in each voxel → reflect vascularity
Virtual non-contrast (VNC): subtract iodine to estimate non-contrast appearance → reduces need for true non-contrast scan

Applications

1. PDAC Detection

Low keV VMI (40-50 keV): amplifies the hypoenhancing tumor against brighter parenchyma - PDAC conspicuity significantly improved
Iodine maps: PDAC has low iodine concentration (reflects desmoplastic hypovascular stroma); normal parenchyma has high iodine
Normalized Iodine Concentration (NIC) tumor < parenchyma = supports PDAC
Detects isoattenuating PDAC occult on conventional CT
Improves margin sharpness and reproducibility of tumor measurements (Insights Imaging, 2022)

2. Differentiating PDAC from Mass-Forming Pancreatitis

AIP/MFP: isoenhancing → higher iodine concentration on iodine map
PDAC: lower iodine density → clear separation on iodine maps

3. PNETs

Hyperenhancing PNETs: high iodine density on arterial phase iodine maps
Treatment response: decrease in iodine density correlates with anti-tumor response (e.g., Lenvatinib) - better than size alone

4. Treatment Response Monitoring

Iodine uptake by PDAC post-chemotherapy reflects vascular response before anatomical size change
Quantitative iodine mapping may add value over conventional CT for monitoring NAT response (Johns Hopkins, Abdom Radiol 2018)

5. Radiation Dose Reduction

VNC images eliminate need for true non-contrast phase in some protocols
Split-detector or rapid kV-switching DECT allows single-acquisition dual-phase imaging

6. Photon-Counting Detector CT (PCD-CT, 2025)

Next-generation DECT; thinner slices, reduced noise, superior iodine density maps
Improved PDAC conspicuity vs. conventional DECT (Abdom Radiol, April 2025)

QUICK REFERENCE TABLE: Pancreatic Solid Lesions

Lesion	CT Enhancement	Key MRI	Demographics	Hallmark Sign
PDAC	Hypo (pancreatic phase), delayed	T1 hypointense (fat-sat), DWI restrict	M>F, >60y	Double duct sign, upstream atrophy
PNET	Arterial hyper	T2 mildly bright, DWI restrict	Any age	Ga-68 DOTATATE positive
SPN	Progressive solid	T1 hyper (hemorrhage), T2 capsule	Young women F:M 10:1	T1 bright hemorrhage + capsule
ACC	Variable/hyper	T2 heterogeneous	M>F	Lipase syndrome; no duct dilation
Hepatoid	Arterial hyper + washout	T1 hyper (bile-like)	Any	AFP elevated
MCN	Macrocystic, septated	T2 bright, T1 proteinaceous	Women, body/tail	No PD communication; ovarian stroma
SCN	Microcystic, central scar	T2 innumerable bright cysts	Older women, head	Sunburst calcification; central scar
IPMN (MD)	MPD dilation	MRCP: MPD >5 mm	Any, older	Patulous ampulla
AIP	Delayed + halo	T2 sausage, capsule hypointense	Older M (I); Young IBD (II)	Sausage sign; halo; steroid response
Groove pancreatitis	Groove plaque	T2 duodenal wall cysts	M, alcohol	Santorini duct cysts
IPAS	Identical to spleen all phases	Identical to spleen	Any	DOTATATE negative; sulfur colloid uptake
Paraganglioma	Arterial hyper	T2 light bulb bright	Any	Metanephrines elevated
RCC met	Arterial hyper	Heterogeneous	Prior RCC	Known primary; hypervascular
Lymphoma	Homogeneous, mild	Iso, minimal enhance	Any, systemic	No calcification, no necrosis, peripancreatic nodes

Sources: Grainger & Allison's Diagnostic Radiology (pp. 695-710); Yamada's Textbook of Gastroenterology 7e (pp. 2771-2785); Current Surgical Therapy 14e (pp. 599, 675-682); NCCN Pancreatic Adenocarcinoma Guidelines v3.2024; Abdominal Radiology 2025 (PCD-CT PDAC); Insights into Imaging 2022 (DECT iodine maps PDAC); PMC 2024 (PACT-UK Radiology Template)

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