BODY CT PROTOCOL DESIGN


 
 Oral contrast: Generally not required for the protocols below.
 
Bladder leak following prostatectomy
 
P
1. Noncontrast scan of pelvis (bladder).
P
2. Fill bladder with contrast through Foley, then rescan pelvis.
P
3. Empty bladder, then rescan pelvis.
 
Evaluation of known renal mass
A
1. Noncontrast images of abdomen only
● Baseline to distinguish calcification and intrinsic hyperattenuation from true enhancement.
● Alternatively, dual energy CT can be used to create a virtual noncontrast dataset.
A
2. Arterial (corticomedullary) phase of abdomen only
● Conventional clear cell RCCs and their metastases demonstrate arterial enhancement.
A
3. (Exclude for young patients) ± Venous (nephrographic) phase of abdomen only
● Pattern of enhancement across multiple phases can help distinguish pathologic subtypes of RCC (clear cell, papillary, chromophobe).
● Evaluate for renal vein invasion.
● Evaluate for hepatic metastases from hypovascular RCC variants.
A P
4. Delayed (excretory) phase (5 min) of abdomen and pelvis
● Papillary RCCs demonstrate delayed enhancement.
● Evaluate for filling defects in collecting system.
● Helps distinguish mixing artifact from thrombus in IVC.
Hematuria
 Hematuria can be caused by a lesion anywhere in the collecting system, from the kidneys to the urinary bladder. This protocol is similar to the renal mass protocol, except that the pelvis is also imaged during arterial phase to evaluate for transitional cell carcinoma of the bladder.

A
1. Noncontrast images of abdomen only
● Baseline to distinguish calcification and intrinsic hyperattenuation from true enhancement.
● Alternatively, dual energy CT can be used to create a virtual noncontrast dataset.
A P
2. Arterial (corticomedullary) phase of abdomen and pelvis
● TCC demonstrates arterial enhancement and can occur anywhere from the kidneys to the urinary bladder.
● Conventional RCC metastases usually most conspicuous on arterial phase.
A
3. (Exclude for young patients) ± Venous (nephrographic) phase of abdomen only
● Evaluate for renal vein invasion.
● Evaluate for hypovascular hepatic metastases.
A P
4. Delayed (excretory) phase (5 min) of abdomen and pelvis
● Evaluate collecting system for filling defects.
● Helps distinguish mixing artifact from thrombus in IVC.

 
Illustrative cases
 
Case 1: 69 year old man with transitional cell carcinoma of the right renal pelvis, which can be visualized on the corticumedullary phase (A) as enhancing soft tissue against urine in the renal pelvis, or on the delayed phase (B) as a filling defect in the opacified collecting system.

(A) Corticomedullary phase
(B) Delayed phase
Case 2: 77 year old woman with papillary transitional cell cancer of the bladder. Importance of bladder distention. TCC on the posterior wall will be well visualized on both arterial and delayed phase if the lumen is adequately distended.

(A) Arterial phase
(B) Delayed phase
Pyelonephritis
 Acute uncomplicated pyelonephritis does not require imaging. CT is warranted and preferred over ultrasound to evaluate for complications (e.g. emphysematous pyelonephritis, parenchymal or perinephric abscess, obstructed pyelonephritis, papillary necrosis) in scenarios such as:
● Failure to improve after 48-72 hours of antibiotics
● Sepsis
● Immunosuppression
● Symptoms of renal colic, or history of renal stones
● Diabetes
● Prior renal surgery
Pyelonephritis will be missed on noncontrast CT in the absence of renal enlargement or perinephric stranding.
 
A P
1. Venous (nephrographic) or delayed (excretory) phase of abdomen and pelvis
● The perfusion defects in pyelonephritis are actually most visible on delayed (excretory) phase.
Illustrative case: 51 year old woman with pyelonephritis of the left kidney. Coronal MPRs from venous (A) and delayed (B) acquisitions after IV contrast administration. Note geographic regions of decreased parenchymal enhancement seen best on the delayed images.

(A) Venous phase
(B) Delayed phase
 
 
Stone
 
A P
1. Noncontrast images of abdomen and pelvis
Noncontrast CT has poor sensitivity for pyelonephritis, renal mass, and renal infarct.
 
 
BROUGHT TO YOU BY:          MY-LINH NGUYEN, MD            KRISTIN PORTER, MD, PHD          PAMELA JOHNSON, MD
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