Bilateral congenital hydronephrosis associated with hypertension in an infant

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Bilateral congenital hydronephrosis associated with hypertension in an infant

Bilateral congenital hydronephrosis associated with hypertension in an infant

Prof. Jan Baxa, MD, PhD
Department of imaging methods, University Hospital Pilsen and Medical Faculty of Charles University, Pilsen, Czech Republic

2025-05-14

A cVRT image shows a posterior view of the three renal arteries, two on the left and one on the right, without signs of stenosis. An accessory artery, originating off the aorta on the right, between the CA and the SMA, is seen, departing upwards to the left hepatic lobe.

History

A 5-month-old baby, suffering from severe hypertension, was presented to the hospital. Ultrasound examination showed bilateral congenital hydronephrosis. Dynamic renal scintigraphy revealed a significant reduction of the right renal parenchyma along with a symmetric split function of 32%. A vesicoureteral reflux (VUR), grade IV, passive and active, and a moderate hypofunction were shown on the left. A contrast CT scan of the abdomen and pelvis was performed with a dual source photon-counting detector (PCD) CT, NAEOTOM Alpha.Pro, to rule out renovascular etiology of the hypertension prior to pyeloplasty.

Diagnosis

CT images showed three renal arteries – two on the left and one on the right – all free from stenosis. An accessory artery, originating off the right side of the aorta, between the celiac artery (CA) and the superior mesenteric artery (SMA), was seen, departing upwards to the left hepatic lobe. Other arteries, within the scope of the examination, were unremarkable. The aorta appeared slender. Bilateral hydronephrosis was seen, more severe on the right, showing a marked reduction of the renal parenchyma with a loss of corticomedullary differentiation. The renal pelvis was 27 mm wide, with a thickened wall of 4 mm on the right and 20 mm on the left. No dilation was seen in the bilateral ureters. The catheterized bladder was empty. There was no free intraperitoneal fluid. An ureteropelvic junction obstruction was suspected and subsequently confirmed by a successful translumbar pyeloplasty surgery (Anderson-Hynes). The patient recovered well and remained normotensive during regular surveillance.

A coronal MPR image shows bilateral hydronephrosis, more severe on the right, with a marked thickening of the pelvic wall. A MIP image and a cVRT image show three renal arteries, two on the left and one on the right, without signs of stenosis. An accessory artery, originating off the aorta on the right, between the CA and the SMA, is seen, departing upwards to the left hepatic lobe. — Courtesy of Department of imaging methods, University Hospital Pilsen and Medical Faculty of Charles University, Pilsen, Czech Republic

Fig. 1: A coronal MPR image (Fig. 1a) shows bilateral hydronephrosis, more severe on the right, with a marked thickening of the pelvic wall. A MIP image (Fig. 1b, anterior view) and a cVRT image (Fig. 1c, posterior view) show three renal arteries, two on the left (arrows) and one on the right (dotted arrow), without signs of stenosis. An accessory artery (arrowhead), originating off the aorta on the right, between the CA and the SMA, is seen, departing upwards to the left hepatic lobe.

MIP images show three renal arteries – one on the right and two on the left – all free from stenosis. — Courtesy of Department of imaging methods, University Hospital Pilsen and Medical Faculty of Charles University, Pilsen, Czech Republic

Fig. 2: MIP images show three renal arteries – one on the right (Fig. 2a, dotted arrow) and two on the left (Fig. 2b & 2c, arrows) – all free from stenosis.

Comments

Hypertension in infants can be caused by renovascular or renal parenchymal disease, such as renal artery stenosis or congenital hydronephrosis. If the renovascular etiology is ruled out, the hypertension can be normalized following a relief of the ureteropelvic junction obstruction, one of the most common causes of congenital hydronephrosis, by pyeloplasty.

CT angiography (CTA) is performed for vascular imaging in infants due to its non-invasive nature. However, there are multifold challenges. Firstly, images need to be acquired at free breathing, if anesthesia is not desired, as infants are incapable of cooperating with breathing command. Secondly, high spatial resolution is needed to visualize the tiny vascular structures, such as renal arteries. Thirdly, as infants are vulnerable to radiation, the dose applied should be as low as reasonably achievable (ALARA). And if renal function is impaired, such as in this case, a reduction of the contrast agent must be considered as well.

This case is performed with a new dual source PCD CT, NAEOTOM Alpha.Pro. It allows for a fast-scanning speed of 491 mm/s, enabling a complete acquisition of 288 mm in 0.56 s with 66 ms temporal resolution per image. There are no motion artifacts observed in the images acquired at free breathing. 70 kV X-ray tube voltage was automatically selected by the system, in combination with virtual monoenergetic image reconstruction at low keV (55 keV). These settings contribute to the improvement of image contrast, which is further enhanced by the intrinsically higher iodine contrast of a PCD-CT, and to the reduction of radiation dose. Three tiny renal arteries as well as a small hepatic accessory artery are depicted, providing important information for surgical planning. Renal artery stenosis is successfully ruled out, using only 12 mL of contrast agent and 1 mGy radiation dose, owing to a combination of high spatial resolution, fast speed acquisition and increased contrast enhancement.

Examination Protocol

Scanner	NAEOTOM Alpha.Pro
Scan area	Abdomen/pelvis
Scan mode	Flash scan (Quantum)
Scan length	287.6 mm
Scan direction	Cranio-caudal
Scan time	0.56 s
Tube voltage	70 kV
Effective mAs	96 mAs
IQ level	120
Dose modulation	CARE Dose4D
CTDI_vol	1.1 mGy
DLP	36 mGy*cm
Rotation time	0.25 s
Pitch	3.2
Slice collimation	96 x 0.4 mm
Slice width	0.4 mm
Reconstruction increment	0.2 mm
Reconstruction kernel	Bv40, QIR 4
KeV level	55 keV
Spectral reconstruction	Monoenergetic Plus
Contrast	350 mg/mL
Volume	12 mL + 20 mL saline
Flow rate	2.3 mL/s
Start delay	Bolus tracking triggered at 350 HU in the descending aorta + 3 s

The statements by customers of Siemens Healthineers described herein are based on results that were achieved in the customer’s unique setting. Since there is no “typical” hospital and many variables exist (e.g., hospital size, case mix, level of IT and/or automation adoption) there can be no guarantee that other customers will achieve the same results.

The products/features (mentioned herein) are not commercially available in all countries. Their future availability cannot be guaranteed.

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