Imaging of Stomach

IMAGING OF STOMACH

Speaker- Dr K Sharma

Moderator- Dr Subhaschandra ,Asst Prof.

INTRADUCTION The stomach is the widest part of the alimentary

tract and lies between the oesophagus and the duodenum

It is situated in the upper abdomen, extending from the left upper quadrant downwards, forwards and to the right, lying in the left hypochondriac, epigastric and umbilical areas.

It occupies a recess beneath the diaphragm and anterior abdominal wall that is bounded by the upper abdominal viscera on either side.

Mean capacity increases from 30 ml at birth, to 1000 ml at puberty, & 1500 ml in adults.

Development Stomach develop from foregut. During week

4, where the foregut tube begins to dilate, forming an enlarged lumen in the tube.

Dorsal border grows more rapidly than ventral, which establishes the greater curvature of the stomach.

A second rotation (of 90 degrees) occurs on the longitudinal axis establishing the adult orientation of the stomach.

Anatomy The stomach is divided into the fundus, body, pyloric

antrum and pylorus, by arbitrary lines drawn on its external surface.

The fundus is dome shaped and projects above and to the left of the cardiac orifice to lie in contact with the left dome of the diaphragm. It lies above a line drawn horizontally from the incisura cardiaca to the greater curvature.

The body extends from the fundus to the incisura angularis, which is a constant external notch at the lower end of the lesser curvature.

The pyloric antrum extends from incisura- gtr curve line to the sulcus intermedius. At this point, the stomach narrows to become the pyloric canal (1-2 cm) in length and terminates at the pyloric orifice

The lesser curvature extends between the cardiac and pyloric orifices and forms the medial (posterior and superior) border of the stomach

The greater curvature is four or five times longer than the lesser. It starts from the incisura cardiaca.

The opening from the oesophagus into the stomach is the cardiac orifice (40 cm from the incisor teeth).

The pyloric orifice is the opening into the duodenum. The circular pyloric constriction on the surface of the stomach usually indicates the location of the pyloric sphincter and is often marked by a prepyloric vein crossing the anterior surface vertically downwards.

The pyloric sphincter is a muscular ring formed by a marked thickening of the circular gastric muscle interlaced with some longitudinal fibres.

Arterial supply – Via Coeliac axis.

The left gastric artery arises directly from the coeliac axis.

The splenic artery gives origin to the short gastric arteries as well as the left gastroepiploic artery and posterior gastric artery.

The hepatic artery gives origin to the right gastric artery and the gastroduodenal artery.

Venous drainage- ultimately into the portal vein via rich submucosal and intramural network of veins. They drain either into the splenic or superior mesenteric veins although some pass directly into the portal vein.

Network of lymphatics At the gastro-oesophageal junction the

lymphatics are continuous with those draining the lower oesophagus.

In the region of the pylorus they are continuous with those draining the duodenum.

In stomach, they follow the course of the arteries supplying the stomach, however many separate node groups are now recognized .

Pancreatic and hepatic lymphatics play a considerable role in draining areas of the stomach during disease process.

Nerve supply The stomach is innervated by sympathetic

and parasympathetic fibres. The sympathetic supply originates from the

fifth to twelfth thoracic spinal segments. The parasympathetic supply is from the

vagus nerves . The anterior nerves are mostly from the left vagus and the posterior from the right vagus, both emerging from the oesophageal plexus

Wall

The gastric wall consists of mucosa, submucosa, muscularis externa and serosa, together with gastric vessels and nerves.

Gastric secretions

Parietal cells(isthmus/neck)--- Acid, IF, PG

Chief cell(base)--- Pepsinogen Pepsin

G Cell ( gastric antrum)--- Gastrin

Superficial/Neck mucous cell--- Mucus.

Mucosal Histology

Gastric Motility– after feeding Receptive relaxation--- fundal relaxation Gastric accomodation---relaxation/ no rise of

pressure. Peristalsis--- over body and antrum mixing/

grinding. Constant tone at pylorus. Emptying--- not due to peristalsis. D/T

transient abolition of pyloric tone as the antral peristalsis sweep through it.

Fasting state--Migrating Myoelectric Complex(MMC).

Luminal surface anatomy. Mucosal fold/ Rugae– Parallel to long axis.

More on body and fundus. 3-5mm in thickness. Smooth and regular. Become less prominent with distension.

Smaller longitudnal fold– seen over antrum leading to pylorus.

Multiple fine transverse fold– mainly in antrum. Persist during distension. Partially collapse with peristalsis.

Abnormal in – Ca, PUD and other pathologies.

Micromucosal pattern Areae Gastricae--- Mosaic or tiny raised

nodules with intervening grooves d/t Ba trapped in cris-cross groove(sulci gastricae). <3mm in diameter. Seen throughout , more over antrum. Seen both in distended and non distended stomach.

Best demonstrated by high density low viscosity Ba.Seen in 50-75% of quality DCBS.

Denotes adequate coating. Abnormal in PUD, gastric tumour, diffuse

atrophic gastritis etc.

Barium meal Ba sulphate is till safest and palatable. Indications– Epigastric pain s/o PUD,

anorexia, wt loss, vomiting, anaemia, heartburn, dysphagia. Etc.

CI– Avoided in susp. GD perforation.

-- care to be taken in h/o or susp. Aspiration.

Water soluable contrast is used in such cases Barium may lead to granuloma formation and

preitoneal fibrosis. Rarely Ba emboli to lung, electrolyte disturbances, hypovolumia, aspiration and pulm edema can occur.

6hr fasting, refrain smoking… Susp.GOO… plain x-ray abd taken. Inj metaclopromide. IV glucagon 0.1mg—to produce hypotonicity.

(CI—insulinoma, pheochromocytoma) Inj Buscopan 20mg--- to inhibit motility.

{transient pylorospasm} Antifoaming agents like simethicone–

increase coating.

SCBM

50 ml LD 100% w/v Ba susp. given.

Supine RAO and Prone LPO Views taken. Pt in prone ..more diluted about 100ml Ba

25-50%w/v given by straw/tube.

Prone LPO, Supine, Supine RAO, and erect RAO views taken.

Addl View if needed.

DCBE Gas producing agent/tablet and iv glucagon. Stand erect 30-45 degree RAO – swallow abt 100 ml HD

250% w/v Ba susp.With Lt handView taken. Horizontal prone…S/C view of antrum Turn/rotate pt 360 degree. Supine film --D/C body/antrum & S/C Fundus. Supine oblique views– RAO & LAO. RT Lat view– D/c Fundus Steep RAO View– duodenal cap/loop.(D/C) Lt Lateral view 45degree head up– D/C duodenal cap. Vertical/ erect view.

Double-contrast spot supine-- benign lesser curvature gastric ulcer.

Biphasic study

SCBA + DCBA Initially DCBA 75ml HD Ba study Followed by SCBA – large volume upto

350ml LD Ba 15-25%.

CT Superior to barium for evaluation of gastric wall and

extralumunal disease. Proper CT need gastric distension with positive or

negative contrast agents. Approx 500 ml of oral contrast agent is given in 2 doses to

distend stomach.(1hr and 30mts before.) Additional 250ml 5mts before scanning.

In addition ,intravenous contrast material (120 mL of nonionic contrast material at a rate of 3 mL/sec.) followed by supine scanning.

Gastric imaging has been improved by the introduction of multidetector row CT scanners

Multidetector row CT offers considerable flexibility; & data can also be reconstructed.

Contrast material-enhanced CT scan obtained with water as an oral contrast ---normal appearance.

MRI MRI has failed in making significant impact in

imaging of stomach due to limited anatomic resolution, motion artifect, and lack of readily available oral contrast agents.

Preparation.. Fast for 4-6hrs, use of glucagon and use of positive or negative contrast agents and IV contrast.

PET/CT fusion imaging:

Valuable in gastric malignancy. Currently used for staging and restaging and response to therapy esp in lymphoma.

Endoscopy US A 12-mm-wide gastroscope is passed to the stomach

with US device at the tip of the gastroscope. During the examination, the stomach may be filled with

200–500 mL of deaerated water to create an acoustic window.

Endoscopic US provides useful information regarding the depth of mural invasion, the horizontal extension of the lesion, and perigastric lymphadenopathy.

Standard endoscopic US images demonstrate five layers of the gastric wall-

superficial mucosa or interface (hyperechoic), deep mucosa (hypoechoic), submucosa (hyperechoic), muscularis propia (hypoechoic), and serosa or outer interface (hyperechoic).

Conv USG Also used esp in childrens with suspected

Hypertrophic pyloric stenosis. Mostly used for assesment of wall and

extraluminal pathology. Use restricted due to availability of more

specific techniques.

Endoscopic US image shows the normal appearance.

Recent Advances. Three-dimensional Imaging CT

Advantages of 3D volume rendering are added perspective and enhanced depth perception. A tortuous vessel or complex mass can be visualized in its entirety with 3D imaging & relationship to adjacent structures can be better appreciated.

Virtual gastroscopy -the CT data of the stomach can be manipulated to simulate endoscopic images (virtual gastroscopy). This display technique accentuates the stomach wall and folds.

Endoluminal imaging provides a view similar to the endoscopic view. With this technique, it is possible to simultaneously visualize the primary tumor and extraluminal extension.

Image from virtual gastroscopy shows the polypoid mass.

Transparency-rendered image shows the mass (arrows) in the lower body of the stomach.

Prepyloric web(antral mucosal diaphragm) Diaphragm like ,exaggerated fold of gastric

mucosa oriented longitudnal to long axis of ST. Thin web demarcate the distal antrum into 3rd

small chamber betwn prox antrum & D bulb. Usually asympt. Rarely GOO.

Diverticula MC in post. Aspect of fundus. Rarely in antrum True diverticula with peristalsis, fills barium. <1cm, lenticular shape with small opening. May be mistaken for ulcer.

Incomplete antral web--concentric radiolucent band (arrows) producing discrete antral lumen reduction.

Gastric duplication- Rare. Extend posteriorly from Gtr curvature. Do not communicate with lumen.

- CT- Non enhancing water density mass.

- MRI- SI depends on contents. Heterotopic pancreas. Situs anomaly-

Situs inversus- Mirror image to normal position.

Situs ambiguous- abnormal orientation.

CT --near-water-attenuation spheric mass (arrows) in close contact with the gtr curve with no communication between the cystic lumen and the true stomach lumen --duplications

Hypertrophic pyloric stenosis Cong disorder diagnosed in infancy. Rarely in

adult. D/t hypertrophy and hyperplasia of circular muscle with some contribution from long muscles.

Radiologically- lengthening of pylorus channel >1.5cm with smooth symm narrowing.

--Hypertrophic muscle(width>3mm) bulges retrograde into antrum creating ‘shoulder’.

-- No peristalsis through pylorus. US can provide definate diagnosis. Acquired cases– d/t sequele of peptic ulcer or

inflm disease. There is lack of retrograde bulge.

Gastric Ulcer Common GI disease. Almost 95% benign. 70% show H Pylori

infection. Rest due mainly to NSAIDs and alcohol use.

MC in distal stomach along lesser curve.. Post wall more common. NSAID/Alcohol related– more commonly

seen in Gtr curve of antrum. Other factors- stress, smoking, steroids,

hereditary etc.

Differentiation into benign, intermediate or malignant is important as benign ulcer is treated medically and intermediate/malignant ulcer need endoscopy and biopsy.

Most benign ulcer on DCBS are 5-10 mm size, round , oval , tear drop or linear contour.

‘Giant ulcer’ >3cm are almost always benign with high risk of perforation/bleeding.

Most gastric ulcers are not visible at CT because they affect only the superficial layers of the gastric wall. However, deep ulcers or ulcers that have penetrated or perforated the gastric wall can be detected.

Primary sign in barium study.. Collection of Ba in dependant wall.

Non-dependant ulcer—’Ring shadow’ with Ba coating the edge of ulcer crater.

A smooth mound of edema often seen sorrounding ulcer as ‘circular filling defect’.

Healing ulcer.. Smooth, symm radiating folds extending to ulcer edge.

Nl Araea gastricae extending to crater..good sign/benign.

Ulcer en face

Benign ulcer- in profile ‘Ulcer niche’ projecting beyond stomach lumen. ‘Hamptons line’ ..pencil thin line of lucency

crossing ulcer base (preserved gastric mucosa). ‘Ulcer collar’– thicker 2-4mm smooth rim of

lucency at base. ‘Ulcer mound’—d/t asscd edema with ulcer. Symm

gently sloping mass. Healing ulcer– shape changes to linear crevices,

subtle retraction or stiffning of wall, uniform folds converging to sides, residual pit/depression etc.

Benign gastric ulcer -an ulcer in the distal antrum with a large surrounding mound of edema

Suspicious of malignant ulcer

Incomplete healing. Irregularities of folds. Residual mass Loss of mucosal pattern.

Complications- Perforation ,

Narrowing/obstruction,

malignant changes

Gastric ulcer. Coronal reformatted image antral ulcer.

Double-contrast spot image of gastric body –

malignant gastric ulcer due to lymphoma.

Gastric erosions Shallow ulceration that do not penetrate musc.

Mucosa. Small shallow colln of Ba 1-2mm sorrd by

radiolucent rim of edema(complete erosion). When halo of edema Is lacking—Incomplete.

Appear short linear or serpentine lines or dots of Barium.

Best detected by DCBa (complete) and endoscopy(incomplete).

Heal without scarring.

Gastritis Mostly caused by H Pylori, Alcohol & NSAIDs. Findings- thick >5mm folds with or without

nodularity. Erosions are also seen with H Pylori gastritis.

Other sign- antral narrowing, Inflm polyp, & prominent areae gastricae.

Radiological and endoscopy findings similar. Radiology—lack of specificity. CT finding-- thickening of the gastric folds and wall.

severe cases-- gastric wall will demonstrate low attenuation compatible with submucosal edema and inflammation. The mucosa may enhance giving the wall a layered appearance in arterial phase imaging.

3D-endoluminal image in gastritis-- moderate diffuse fold thickening

Atrophic gastritis

Atrophy of glands + inflammation. Assd with pernicious anaemia. Association– G polyp, Ca, Intestinal

metaplasia. Radiology..loss of rugal fold, tubular

featureless narrow stomach, Areae gastricae may be absent.

Infectious gastritis H Pylori MC offender. TB, Syphilis,

Candidiasis, and CMV/CryptoS/TOXO in IC pt.

Ulceration, thick folds, & mucosal nodularity common. Antral narrowing late.

CMV—deep ulcer/ fistula. Cryptosporadium-Deep ulcer, narrowing. Crohn disease- GD inv in 20% cases. Mostly

involve antrum and body. Ulcer, thick distorted folds, nodular mucosa, scarring and narrowing(Funnel or rams horn shape) etc

Hypertrophic gastritis. Radiology- thickened olds >10mm in width, mostly

in body and fundus. Areae gastricae are prominent upto 4-5mm in size

and are more angular and polygonal.

Menetrier disease Chrz by hypertrophy of gastric glands, achlorhydria,&

hypoprotenemia leading to protein losing enteropathy.

Markedly enlarged pliable folds(prox St/gtr curve), increased fluid in lumen.

Antrum involvement only in 50% cases causing diffuse involvement.

Ménétrier disease--large, lobulated folds and preserved gastric mucosa in the fundus.

ZES Chrz by thickened gastric folds and

increased gastric secretion. Caused by gastrinoma.(MEN type I) CT- Marked diffuse wall thickening,

ulceration or large fluid volume.

Eosinophilic gastritis Focal/diffuse infiltration of st esp antrum by

eosinophils(mucosa/Muscles/serosa). Thickened folds, antral narrowing or rigidity.

Corrosive gastritis Caustic chemicals, acids etc can cause

necrosis with slaughing of mucosa/submucosa. Severe cases may lead to perforation, fibrosis or stricture.

Radiological findings depend on severity. Swelling, irregularity, blebs etc seen early.

Later-- slaugh/ ulcer, fibrotic contraction etc seen.

Gastric volvulus Stomach twists between points of its normal

anatomical fixations leading to GOO and vascular compromise.

Usually assd with sliding or paraesophageal HH. Two types- organoaxial-rotate along long axis.

May be to right or left.

--Mesentricoaxial- less common. Rotate along axis perpendicular to long axis. Upside down.

Radiological app/Barium study depend on type of volvulus.

Gastric varices Seen in portal HTN or with esophagial varices. Isolated gastric varices often is a sign of splenic vein

thrombosis. MC in fundus or prox part. Appear as widened, effaceable polypoid folds. May

be nodular ‘grapelike’ or masslike. TAS/ endoscopic US are important for diagnosis. CT is valuable.Gastric varices appear as enhancing

tubular vessels, located primarily along the body and fundus of the stomach. Because they are veins, they will enhance during the portal venous phase and will not typically enhance during the arterial phase

Gastric outlet obstruction Can cause Obstructive distension. Obstructive– PUD(MC) & Gastric cancer (90%).

-- spasm, scarring, acute inflm,

muscle hypertrophy, crohn’s, TB,

sarcoidosis , syphilis etc.

Imaging- Dilated air/fluid fillrd stomach.

Mottled pattern of air and residual content

Ba study is not ideal for distended ST.

CT is superior- finding out the cause.

Non- Obstructive distension-

Seen in A/C trauma & post op (A/C)

Diabetes with gastroparesis (C/C)

Gastric Pneumatosis

May be incidental or d/t gastric emphysema or emphysematous gastritis.

Cause-Infection by gas forming agents like E coli, caustic ingestion, trauma, infarction etc.

CT- wall thickening with mural gas.

POST OPERATIVE STATUS-

In gastrectomy and gastrojujenostomy, or bypass surgeries , post op complications may be

- Immediate like leakage,abscess, bleeding, or obstruction.

- Delayed like tumour recurrance, bezoar, or obstruction.

CT is important in evaluation of such cases.

NEOPLASM BENIGN- Gastric Polyps.

- GIST

- Neuroma, schwannomas etc

- Gastric lipoma.

MALIGNANT- Gastric CA.

- Gastric Lymphoma.

- Malignant GIST

- Gastric carcinoids.

- Metastatic disease.

Benign Neoplasm Hyperplastic Polyp- MC benign neoplasm.

No malignant potential.

- round ,smooth sessile lesion.

- Usually multiple of uniform size(5-10 mm)

- MC in fundus and body.

- Identified in upto 40% pt with FAP coli.

Double-contrast spot image-

Dependent-- round or ovoid, finely lobulated radiolucent filling defects in barium pool.

Nondependent-- are coated by barium and appear as white lines

Double-contrast spot image of multiple hyperplastic polyps on dependent & nondependent Areas.

Adenomatous Polyp- Premalignant for G.Ca. seen Histologically in 50% , >2cm size.

- Assd with FAP coli.

Adenoma- Polypoid, solitary >1cm , usually in

antrum. May be sessile or lobulated.

Villus adenoma- Numerous frondlike

projection & appear bubbly radiologically

- High malignancy risk.

Gastrointestinal stromal tumour GIST Gastrointestinal stromal tumors (GISTs) are

uncommon neoplasms that arise from mesenchymal cells in the wall of the gastrointestinal tract.

Stromal tumors can be classified histologically as

--myogenic tumors (arising from smooth muscle),

--neurogenic tumors (arising from neural elements), or less differentiated tumors (GISTs).

Stromal tumors with smooth muscle differentiation were formerly called leiomyomas or leiomyosarcomas. They account for only 1% of gastric tumors and usually occur in adults. .

GIST arise from smooth musle pacemaker cell of cajal, and express tyrosine kinase GF. They do not contain smooth muscle cell.

Distinctly different from leiomyoma/sarcoma. Occur over age of 50yrs, Stomach MC

location(44%) in GIT. Mostly benign, difficult to asses malignant

potential. Tmr >5cm has chance of metastasis. They usually outgrow blood supply & necrose.

CT--GISTs vary in size and appearance. Small tumors appear as intramural masses . When large (>5 cm), the tumors often appear exophytic and may contain areas of central necrosis or calcification.

Associated adenopathy is uncommon, in contrast with gastric adenocarcinoma or lymphoma.

Malignant GIST-invade adjacent organs and can metastasize usually to the lung or liver.

CT cannot differentiate between malignant and benign GIST unless obvious local invasion or metastatic disease is seen. Small tumors (<4–5 cm) are usually benign.

MR –variable SI. Usually large tmr show peripheral enhancement and smaller tmr show homogenous enhancement.

Percutanous biopsy not done- needle pathway seeding.

Benign GIST of the stomach -a round, hyperenhancing, submucosal soft-tissue mass with a small central ulcer .

Contrast-enhanced 3D volume-rendered CT -exophytic mass (arrows) that arises from the stomach. (GIST)

Malignant- GASTRIC CA Early gastric CA—

-Lesion confined to gastric mucosa & submucosa with no invasion to muscles layer regardless of LN or metastasis..

- DCBS- Flat lesion or shallow ulceration with converging folds.

- Folds are often thickened, irregular, nodular or club like appearance.

- Ulcer are frequently irregular and on compression filming , do not extend beyond lumen.

Japanese classification of early gastric cancer

>0.5 cm in heights.

<0.5 cm in heights.

Minimal/no HT changes

Sup. Erosion < MM.

Prominent d/t ulceration

Advanced Gastric CA Adenocarcinoma is by far the most common gastric

malignancy, representing over 95% of malignant tumors of the stomach . MC 6th to 8th decade.

Frequently presents as large , irregular mass that may or may not ulcerate. Margins may exhibit a shelf, forming acute angle with wall indicating mucosal origin.

When antrum is involved– narrow/obstruction. Lintis plastica--diffusely infiltrating Ca with

considerable fibrosis. Radiologically appear as narrowed , rigid stomach.

Insvg options- Radiological, endoscopic and biopsy.

Histology: 4 types- Mucinous.

-Signet ring cell scirrhous(lintis pl).

- Papillary.

- Tubular. Spread of tumour– local extension, distant metastasis,

drop metastasis etc. LN>8mm in short axis is considered positive.

CT– focal wall thickening, diffuse wall thickening(lintis pl), or lobulated mass with or without ulceration.

-Early Ca– increased enhancement of inner mucosal layer with low density intact submucosa.

-Advanced Ca- Distruction of multilayer pattern with transmural enhancement.

--Wall thickning >1cm– 100% sensitive for cancer.

--Addl findings may be focal, eccentric or enhancing wall thickness.

Borrmann classification of advanced gastric cancer.

I- >3cm with alrge irrg lobulations. Irregular tumour shadow with rough lobulations.

II- >3cm, Localised filling defect of wall . Irrg crater with raised margins & sharp set off.

III- Larger than II, Filling defect + stiffning. Ba- irrg crater with sorrdg radiolucency. Diffuse infiltration(stiffning beyond crater)

IV- Diffuse infiltrative Ca,Deformity of stomach d/t infiltration/prolfn of fibrous tissue.Narrow antrum, poor distension.

CT CT is currently the staging modality of choice as it identify

the primary tumor, assess for local spread, and detect nodal involvement and distant metastases

When water is used as an oral contrast agent, gastric tumors appear as segmental or diffuse wall thickening that may demonstrate enhancement unlike that of the normal adjacent gastric wall .

Arterial phase imaging would be beneficial for vascular imaging and often accentuates the differences in appearance between normal gastric wall layers and tumor.

Axial images have always been useful in the staging of gastric malignancies.

Multiplanar reformatted images and 3D images improve the detection and staging of both early and advanced tumors .

Coronal contrast-enhanced 3D volume-rendered multidetector row CT scans obtained in a patient with gastric cancer.

Ulcerated carcinoma of the stomach contrast-enhanced CT image shows focal asymmetric thickening double-contrast UGI tract image shows a polypoid mass (black arrows) with a flat central ulcer

Scirrhous carcinoma of the stomach focal circumferential thickening of the wall of the gastric antrum /irregular narrowing of the gastric antrum

Pathologic TNM Staging System Developed by American Joint Committee on Cancer and International Union Against Cancer in 2002

Axial CT scan ulcerated carcinoma lesser curvature-- multiple round, hyperattenuating, metastasis-positive lymph nodes (pN2).

CT Criteria for T and N Staging of Gastric Cancer

Spread beyond serosa-- seen as perigastric reticular stranding or obliteration of adjacent fat plane.

Pancreatic invasion- obliteration of fat plane.

EUS is more sensitive in tumour stage and LN.

MRI—

Limited role. Limitations in spatial resolution and nodal staging.

Gastric lymphoma

Stomach is MC site of GI Lymphoma. Most of them are NHL type.

No typical radiographic appearance, may mimic any gastric carcinoma.

MC- infiltrating lesion extending over large area of ST with diffuse gastric fold thickening. Or may appear bulky polypoidal mass, or malignant ulcer.

MALT lymphoma is a low-grade lymphoma that is being recognized with increasing frequency. It is thought to be associated with Helicobacter pylori(acquired).(normally no lymphoid tissue in ST)

Perigastric adenopathy is common in patients with gastric lymphoma (bulky LN).

Gastric involvement may be primary(extension from involved LN) or part of generalized disease.

CT Lymphoma CT--segmental or diffuse wall thickening(4-5 cm).

May also be seen as polypoidal lesion, ulcerating lesion or multiple submucosal nodule.

In contrast to gastric Ca, lymphoma typically involves more than one region of the stomach.

With use of water as an oral contrast agent-- possible to detect cases of only minimal thickening of the gastric wall.

Because lymphoma is considered to be a “soft” tumor—less chance of gastric outlet obstruction than is gastric CA.

MALT Lymphoma- similar to NHL. But wall thickening are more subtle and lymphadenopathy is not prominent.

Contrast-enhanced CT scan --segmental thickening of the gastric antrum (arrow).

Gastric lymphoma --reformatted image shows an early gastric lymphoma as focal thickening of the antral wall.

Gastric Carcinoid 3 types-

I– Benign- with P anaemia or c/c atrophic gastritis.

II– Rare- in setting of ZES/MEN I, LN metastasis common. CT- multiple masses in prox stomach with diffuse fold thickening.

III– sporadic, large solitary mass. Hepatic metastasis and carcinoid syndrome may occur. Hypervascular and poor prognosis.

Metastatic disease

MC primary sites- Breast, MM, lungs. Appear as small intramural masses ,

multiple, indistinguisable from benign disease.

May contain central ulceration, having ‘bulls- eye’ appearance.

Radiographs of the stomach obtained by Lindemann (1897)

virtual gastroscopy –GIST 2009