Table 1.

Imaging modality preferences in common post-transplant complications

Variable	Color Doppler Ultrasonography	Computed Tomography	Magnetic Resonance Imaging	Nuclear Medicine Imaging	Digital Subtraction Angiography
Immediate postoperative graft dysfunction/ATN	Preferred test to establish vascular flowa Strengths: Noninvasive; quick; portable; detailed information on arterial and venous anatomy, flow, velocity. Rules out hydronephrosis and detects early large perinephric collections. Weakness: User-dependant; technical limitations may obscure vasculature	Not used to establish DGF/ATN Strengths: Can detect other intra-abdominal catastrophes Weakness: Risk of contrast nephropathy due to contrast agents in early postoperative period limits vascular evaluation	Not used to establish flow Strengths: None Weakness: Lack of contrast agent in early postoperative period limits vascular evaluation	Preferred test to establish flowa Strengths: Uptake establishes flow; may diagnose leaks Weakness: Not easily available, time consuming, expensive	Not used
Urinary tract obstruction	Preferred test Strengths: Can be serially followed for resolution, grade severity Weakness: Cannot differentiate functional obstruction from chronic dilatation	Strengths: Useful to detect nephrolithiasis-related obstruction and extrinsic causes of obstruction	Not used	Second-line test Strengths: Helps differentiate functional obstruction from chronic dilatation	Not used
Transplant renal artery stenosis	Preferred test Strengths: Reasonably high sensitivity in highly trained centers; can be serially followed Weakness: Vessel angulation may limit diagnostic accuracy; operator-dependent, limited specificity, lack of intervention option	CT angiography not studied extensively in transplants Strengths: Theoretically can achieve high sensitivity and specificity in diagnosis Weaknesses: Risk of contrast nephropathy; lack of intervention option	Strengths: Confirmatory test in cases of equivocal US findings Weakness: Possible high false-positive rates; risk of NSF in GFR <30 ml/min per 1.73 m2 in gadolinium-based studies	Not used	Preferred confirmatory second-line test in cases with high suspicion Strength: Simultaneous intervention option Weakness: Risk of contrast nephropathy
Fluid collections– (hematomas, abscess, lymphocele, urinomas)	Preferred Strengths: Follow serially, simultaneous drainage option Weakness: Low specificity	Preferred second-line test Strengths: High specificity, follow serially for resolution, define surgical intervention	Preferred third-line line test Strength: Useful for equivocal CT and/or US findings	Useful only in cases of urine leaks	Not used
PTLD	Second-line test Weakness: Small lesions cannot be characterized	Preferred Strengths: High sensitivity, detects extrarenal graft lesions, aids in staging Weakness: Lacks specificity, biopsy required, contrast agent may be needed	Preferred Strengths: High sensitivity, detects extrarenal graft lesions, aids in staging Weakness: Lacks specificity, biopsy required, contrast agent may be needed	Not used	Not used
Nephrolithiasis	Useful for serial imaging for resolution	Preferred first-line test Strengths: High sensitivity and specificity; contrast agent not needed	Not used	Not used	Not used
Biopsy/biopsy complications	Preferred modality for biopsy and detecting postbiopsy complications Weakness: Small complications can be missed	Preferred test to serially follow selected complications	Not used	Not used	Preferred second-line test Strengths: High sensitivity and specificity, intervention options, detects small lesions Weaknesses: Contrast nephropathy, inherent risk of procedure

ATN, acute tubular necrosis; DGF, delayed graft function; CT, computed tomography; US, ultrasonography; NSF, nephrogenic systemic fibrosis; PTLD, post-transplant lymphoproliferative disorder.

^aImaging modality preference based on center expertise, emergent availability, and individual initial surgical/clinical course.