Wedge-shaped contrast enhancement

Fig. 5. The reason why we considered that wedge-shaped contrast enhancement reflected a vascular lesion. We infused microspheres in the rat heart, and performed glomerular supervital staining with Alcian blue. In this rat, renal infarction was detected. This was the basis of the hypothesis that wedge-shaped lesions are related to vasoconstriction (p. 4)...

Fig. 72. Wedge-shaped contrast enhancement after the administration of vasopressin in an animal model (p. 73)...

Fig. 2. Plain computed tomography (CT) 22 h after the administration of contrast medium. Wedge-shaped contrast enhancement was observed in the bilateral kidneys (From [1], with permission)...

Fig. 8. Dynamic CT in the presence of wedge-shaped contrast enhancement (0 s)...

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. 

In order to compare kidney function between the areas where contrast persisted and those where contrast did not persist, we performed additional dynamic CT in a patient with wedge-shaped contrast enhancement [14] (Fig. 14, Patient 3). 

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. 17. Comparison of contrast enhancement 24h afterthe administration of contrast medium between exercise-induced acute renal failure (ALPE) and myoglobinuric acute renal failure (serum creatinine 3mg/dl). The patient with ALPE showed patchy wedge-shaped contrast enhancement, and the patient with myoglobinuric acute renal failure showed diffuse contrast enhancement...

Fig. 22. Magnetic resonance imaging (MRI) without contrast medium showed wedge-shaped contrast enhancement in some patients (Patient 16 TR3600, TE138)...

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). 

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

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...

MRI and a bone scan with MDP showed wedge-shaped contrast enhancement in some patients, although these procedures were less sensitive than CT. Patchy lesions could be visualized by a bone scan with MDP in Patients 5 (Fig. 18), 12 (Fig. 33), 13 (Fig. 35), and 16 (Fig. 40). This visualization was achieved by MRI in Patients 6 [35] (Fig. 26), 16 (Fig. 22 and Fig. 39), and 21 (Fig. 45). In the future, ultrasonography with Levovist will facilitate the visualization of lesions. 

Wedge-shaped contrast enhancement was detected in 53 (93%) of the 57 patients who underwent delayed computed tomography (CT) (Fig. 52). However, in the other 4 patients, CT was performed when the serum creatinine level was high. 

Fig. 52. Proportion of patients with wedge-shaped contrast enhancement in those who underwent delayed CT...

On June 6, this patient developed severe loin pain after he participated in two 150-m sprints at a town athletics meeting. After 5 days, he was referred to the outpatient clinic of our department. His serum creatinine and uric acid levels and FEUA, were 2.9mg/dl, 2.1 mg/dl, and 49.7%, respectively. His creatine phosphokinase (CPK) level was normal. When his serum creatinine level decreased to 1.58 mg/dl, a contrast medium was administered. A delayed computed tomography (CT) scan after 24 and 48 h confirmed patchy wedge-shaped contrast enhancement (Fig. 58). Under a diagnosis of ALPE, his body water balance (hydration) was controlled. In this patient, recovery was achieved 4 weeks after onset, and his serum creatinine and uric acid levels were then 1.0 mg/dl and 0.6 mg/dl, respectively. Furthermore, load tests with a uric acid reabsorption inhibitor (benzbromarone) and a uric acid excretion inhibitor (pyrazinamide) suggested presecretory reabsorption defect-related renal hypouricemia. A kidney biopsy 16 days after onset confirmed the recovery from acute tubular necrosis. 

Fig. 58. Wedge-shaped contrast enhancement in Case 1 with ALPE in Fig. 57. a, 24h after b, 48 h after...

ALPE frequently developed after anaerobic exercise, and caused severe loin pain, nausea/vomiting, and slight fever without dark urine. Furthermore, the serum myoglobin and CPK levels were normal or slightly increased, and delayed computed tomography (CT) showed wedge-shaped contrast enhancement. 

In the patients with ALPE, plain CT of the kidney (delayed CT) a few hours, 24 h, and 48 h after the administration of 40 ml contrast medium showed wedge-shaped contrast enhancement. When physicians hesitate to administer a contrast medium, patchy accumulation can be sometimes detected by magnetic resonance imaging (MRI) with gadolinium-diethylenetriaminopentoacetic acid (Gd-DTPA), bone scan with MDP, or ultrasonography with Levovist. 

In addition to ALPE, mild acute renal failure, including dehydration, acute pyelonephritis, and renal pelvic tumors, is visualized as wedge-shaped contrast enhancement [15]. However, acute pyelonephritis and renal pelvic tumors are visualized as unilateral lesions, whereas ALPE is visualized as a bilateral lesion therefore, differentiation is possible. For a definitive diagnosis, the presence of patchy contrast enhancement must be demonstrated when the serum creatinine level is in the range from 1.2 to 3.5 mg/dl. However, as described above, a definitive diagnosis is not always necessary in clinical practice. 

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