CT Abdomen and pelvis · ABDOMEN . Patient preparation Oral contrast material to opacity the...
Transcript of CT Abdomen and pelvis · ABDOMEN . Patient preparation Oral contrast material to opacity the...
Indications
Patient preparation
Patient position
Scanogram
• To assess equivocal imaging findings
• Staging of hepatic neoplasms
• Metastatic workup of primary malignancies
• Diagnosis of abdominal masses
• Assessment of biliary problems
• Diagnosis of vascular lesions
• Assessment of suspected post-traumatic complications
CT
ABDOMEN
Patient preparation
Oral contrast material to opacity the gastrointestinal tract [gastrographin 38% diluted by water to 4%]
- Timing?
Not indicated in Acute abdominal trauma
Acute renal colic
Dehydrated patients
Indications
Patient preparation
Patient position
Scanogram
CT
ABDOMEN
No required preparation unless the patient is going to be sedated
or injected with contrast material
FASTING FOR 4 - 6 HOURS
Scanogram Frontal
10mmscan intervals [ 5mm sections are necessary for pancreas, suprarenal glands, urinary bladder]
Window setting Soft tissue window
Lung window [scans at the lung bases]
Bone window [lesions in the spine or pelvic bones]
Patient preparation
IV contrast material [urographin,…] 60ml
• Fasting 4-6 hours ?!
• Pre contrast scans [ liver, kidney, urinary bladder]
• Triphasic scan for liver [ arterial, portal, delayed]
Detailed examination of the Superior Mesenteric Artery and Celiac Artery. Scan time = 9.4 seconds. 1mm slice thickness
Value of precontrast study
Hyper vascular deposits
Arterial phase
Value of arterial phase
images in hepatic
lesion detection
Male
pelvis
Female
pelvis
LS
MS
AS
PS
Hepatic segmental anatomy
LS MS
AS
PS
LS MS
AS
PS
No focal lesions
?!!
Contrast enhanced CT
or MRI
?!
Diffuse hepatic diseases?!!
Fatty liver
Cirrhosis
Storage diseases
No dilated biliary radicals ?!!
Intra
hepa
tic bi
le du
ct di
latati
on
Vessels in the
liver ?!! Hepatic artery
Hepatic veins
Portal veins
CT Portography
CT Portal venography in a
56Y Male with portal vein
thrombosis
CT Portal venography
showing portal
hypertension with GE
varicosities
Normal variants
Agenesis of the anterior segment of the right hepatic lobe
Porta-hepatis
Hepatic artery
Portal vein
cbd
Pancreas
Anatomy Anterior pararenal space,
retroperitonium Head (3cm) neck, body (2.5cm)
and tail (2cm) Pancreatic density is similar to
unopacified bowel and vessels 5mm sections Pancreas does not have a firm
capsule
Pancreatic atrophy with fatty infiltration, age related
Pancreatitis, acute Pancreas, normal
Pancreatic
anatomy
Pancreatic head, superior mesenteric artery and vein
Suprarenal glands
F 35Y
QUIZ
CASES
1
2
3
MRI Coil selection
Body coil
Phased – array multicoils
• Increases signal/ noise
ratio
• Allows smaller field of view
• High cost
• Very high signal of
subcutaneous fat
Examination protocol
• Coronal localizer
• Axial T1 and T2 WIs
• Coronal T1 and T2 WIs
• Axial T2 fat suppression
• Dynamic post contrast axial T1 WIs
[Arterial , portal and delayed phases with or without fat suppression ]
Normal liver is of similar or higher signal to muscles [T1] Normal liver shows intermediate signal [T2] Spleen shows increased signal compared to the liver [T2]
MRI normal spleen
Multiple Angiomyolipomas T1, T1 Fat sat, T1 fat sat +c
MR advantages
MR is more sensitive in detection
and characterization of hepatic hemangioma
[high signal on heavily T2 weighted sequences]
MR can differentiate focal fatty changes from deposits
In diffuse fatty infiltration hypo dense deposits may
be masked by the hypo dense background of fatty
liver on CT .On MR the background is relatively high
signal in T1 WIs while deposits are of low signal,
so increases the difference
MR is sensitive for detection of hemorrhage
Hemangio
mas
demonstrat
ed by
heavily
weighted
T2 MRI
Normal renal
MRI.
T
1
T1+
C T
2
Normal renal MRI.
[Fat suppression]
T1 weighted images
Normal liver is of similar or higher signal to muscles
• T1 spin echo sequences
• T1 breath hold gradient echo images SPGR/ FLASH
Short TE 5 msec TR> 100mesc
Flip angle 80-90 degrees
Magnetization prepared T1 weighted GRE images [STIR]
very short TR < 10mesc
flip angle 40 degrees
Inversion time 500
T2 weighted images
Normal liver shows intermediate signal
Spleen shows increased signal compared to the liver
• Conventional T2 spin echo sequences
• T2 with rapid acquisition and relaxtion enhancement FSE Difference from T2 SE
• Higher signal intensity of fat on FSE
• magnetic susceptibility artifacts of metals on FSE
• ↑ magnetization transfer effect in FSE→ signal of solid lesions
MRI Fat suppression
Advantages • Decrease motion artifacts
• Improve signal/ noise and
contrast/ noise ratios of focal hepatic lesions
نستغفرك و نتوب اليك @نشهد ان ال اله اال انت @سبحانك الهم و بحمدك
Thank you
Diaphragmatic attachment of the liver
Malignant Colonic polyp