Delayed contrast enhancement

Preliminary studies of collateral circulation in high grade stenoses or occlusions using ultra fast dynamic MRA with temporal resolution in the range of a second did show delayed contrast enhancement in the affected vascular territory, but did not provide relevant additional information compared with conventional MRI and perfusion techniques probably due to the reduced spatial resolution (Wetzel et al. 2001). A dedicated analysis of collateral circulations, especially extra-intracranially, is still the domain of DSA as far as the exact depiction of anatomical connections is of importance. If the exact anastomotic vascular anatomy is not of primary interest, the collateral supply is better determined by MR perfusion techniques. 

Cherryman GR, Pirovano G, Kirchin MA. Gadobenate dimeglumine in MRI of acute myocardial infarction results of a phase III study comparing dynamic and delayed contrast enhanced magnetic resonance imaging with EKG, (201)T1 SPECT, and echocardiography. Invest Radiol 2002 37(3) 135-45. 

Kim RJ, Fieno DS, Parrish TB, et al. Relationship of MRI delayed contrast enhancement to irreversible injury, infarct age, and contractile function. Circulation 1999 100(19) 1992-2002. 

For some dedicated indications it may be useful to acquire an even later phase of parenchymal imaging (>3 min). This phase has shown potential to discern hepatocellular carcinoma (hypoattenuating) and cholang-iocarcinoma (delayed contrast enhancement). 

In several CT studies, a "delayed contrast enhancement was observed in the area of infarction (10 min to several hours after contrast administration), primarily found in recent infarctions, but also reported to be detectable in chronic infarctions (Adams et al. 1976 Mahnken et al. 2005,2007 Fig. 20.8). However, detection of such delayed enhancement requires additional scans with an increased application of the radiation dose to the patient and prolonged examination times therefore, it has hardly been used in clinical routine. It should therefore be the focus of future studies, to assess the diagnostic power of contrast-enhanced CT for the detection of myocardial infarctions, using the standard protocol that is being used widely for CTA of the coronary arteries. Any additional diagnostic information that can be derived from these standard CTA examinations is of considerable interest. 

Although being generally based on CRE techniques, the various clinical applications differ substantially. The major applications of CRE techniques include analysis of cardiac function, using cine techniques, assessment of blood flow based on cine phase-contrast (PC) sequences and myocardial perfusion, as well as delayed contrast enhancement imaging. These different applications are discussed separately within the clinical aspects of cardiac CT and MRI. 

Hypervascular metastases exhibit an early, brief and pronounced signal enhancement in the arterial phase, which fades rapidly in the later phases. These lesions appear hyperintense in the arterial phase, but other hypervascular lesions like HCC, adenoma and FNH may show similar pattern. Hypovascular metastases exhibit a delayed contrast enhancement, which means they appear hypointense in the arterial phase. A maximal lesion-to-liver contrast is reached in the PVR The equilibrium phase is still important, because it can be used for lesion differentiation (i.e. hemangioma versus metastasis). Hemangiomas show persistent enhancement during the equilibrium phase, whereas most metastases appear iso- or hypointense compared to liver parenchyma (Fig. 19.3). 

Yasuda R, Munechika H Delayed adverse reactions to nonionic monomeric contrast-enhanced media. 

Fig. 6. Delayed CT 48 h after the administration of contrast medium. The serum creatinine level was high (5.5mg/dl), and the contrast-enhanced areas were more extensive than those in Fig. 2 (serum creatinine 1.6mg/dl). Patchy contrast enhancement changed to diffuse contrast enhancement...

The area of wedge-shaped contrast enhancement increased with the increase in serum creatinine level. When the serum creatinine level exceeded 5 or 6 mg/dl, diffuse contrast enhancement involved the entire kidney. However, even in patients with diffuse contrast enhancement, delayed CT confirmed patchy wedge-shaped contrast enhancement again when the serum creatinine level decreased to 1.2-3.5 mg/dl in the recovery phase (refer to Patient 2 in Fig. 59, Chap. 10, Sect. 1). This finding in the recovery phase cannot be explained by tubular obstruction. 

Subsequently, we examined whether it is only patients with exercise-induced acute renal failure (ALPE) who show wedge-shaped contrast enhancement [15-18]. We performed delayed CT on a patient with ALPE and a patient with myoglobin uric acute renal failure (due to a malignant syndrome) when their serum creatinine levels were 3.0 and 1.5mg/dl, and compared the results. Wedge-shaped contrast enhancement was observed only in the patient with ALPE (Patient 19), and not in the patient with myoglobinuric acute renal failure. Diffuse contrast enhancement was noted (serum creatinine level, 3mg/dl) (Fig. 17). 

Fig. 19. Delayed CT 17h after the administration of contrast medium to the patient in Fig. 18. Wedge-shaped contrast enhancement was observed in the bilateral kidneys (From [22], with permission)...

Wedge-shaped contrast enhancement on plain CT from a few hours to 72 h after the administration of a contrast medium (however, delayed CT after administration of the contrast medium is not essential to making a diagnosis). 

This patient was the first case in our series in which acute renal failure developed after an athletics meeting. After he had participated in a 200-m race, loin pain occurred, leading to acute renal failure. Delayed computed tomography (CT) showed diffuse to patchy contrast enhancement. The details are given in Chap. 2, Sect. 2. 

Fig. 25. Left. Delayed CT 24 h after the administration of contrast medium. The area of contrast enhancement was more extensive than that seen at a serum creatinine level of 1.6mg/dl (Fig. 2) (From [41], with permission). Right. Dynamic CT in the presence of wedge-shaped lesions (72 h after the administration of contrast medium). In a portion of the left kidney (arrows), the medulla was contrast-enhanced 2-3 min later, suggesting that kidney function in this area was normal...

Fig. 27. Delayed CT. Wedge-shaped contrast enhancement was observed, which was consistent with the findings shown in Fig. 26...

Fig. 28. Delayed CT 12, 18, 41, and 96h after the administration of contrast medium. Patchy contrast enhancement persisted for 41 h...

This patient, who had autosomal dominant polycystic kidney disease (ADPKD), almost drowned and then developed ALPE. On July 20, 1990, he nearly drowned in the sea at 1500 hours, and was brought to our hospital by ambulance for dyspnea and severe loin pain at 1620 hours. On admission, metabolic acidosis was observed. His CRP, serum creatinine, CPK, amylase, and urinary protein levels were 1+, 1.5mg/dl, 116 U/l, 592IU/1 (derived from the salivary gland), and 2+, respectively. His body temperature was 37.7°C, and his blood pressure was 110/60 mmHg. His pulse and respiratory rate were 120/min and 22/min, respectively. Delayed CT 6h after the administration of contrast medium showed wedge-shaped contrast enhancement in the noncystic renal parenchyma (Fig. 34). On July 24, a bone scan with MDP revealed patchy lesions (Fig. 35). His serum creatinine level was 1.3 mg/dl, which had decreased to 1.0 mg/dl on July 27. The patient was then discharged. 

Fig. 34. Delayed CT 6h after the administration of contrast medium to an autosomal dominant polycystic kidney disease (ADPKD) patient with ALPE. Top. Wedge-shaped contrast enhancement can be seen in the noncystic renal parenchyma region at onset. Bottom. CT under the same conditions in the recovery phase did not show wedge-shaped contrast enhancement...

This patient, who had ADPKD, developed ALPE after a sprint. On October 1,1995, he participated in two 100-m races at an athletics meeting in the morning. After a few hours, severe loin pain occurred, and he attended our department the following morning. There were no other abnormal findings, and his blood pressure, pulse, and serum creatinine values were 120/66 mmHg, 64/min, and 1.6mg/dl (serum creatinine level before onset 0.9mg/dl), respectively. On October 2, delayed CT 4 and 24 h after the administration of contrast medium showed patchy lesions (Fig. 37). On October 14, his serum creatinine level returned to 1.1 mg/dl, and CT 4h after the administration of contrast medium showed no contrast enhancement. 

Fig. 43. Delayed CT 24 and 48 h after the administration of contrast medium. Contrast enhancement can be detected 48 h after administration, although it is less marked...

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