The imaging appearances of calyceal diverticula complicated by uroliathasis

Abstract

The presence of diverticula arising from the calyceal system is a relatively uncommon urological problem, occurring with an incidence of 2.1-4.5 per 1000 intravenous urogram (IVU) examinations. While the incidence of calyceal diverticula is low, the frequency of stone formation within them is high. We describe the aetiology and clinical presentation and describe the role of imaging with ultrasound, intravenous and retrograde pyelography and CT in diagnosis and planning treatment. We also describe the potential of fluid-sensitive magnetic resonance imaging techniques as a radiation-free alternative to the use of more conventional modalities, such as intravenous urography and retrograde pyelography, in delineating the anatomy of calyceal diverticula before surgical and radiological intervention especially in young patients and pregnant women.

Figure 1

A 55-year-old female with right upper quadrant pain. (a) A supine abdominal radiograph demonstrates a rounded area of calcification in the right upper quadrant (arrow), which was initially misinterpreted as gallstones. The patient was subsequently referred for abdominal ultrasonography. (b) Longitudinal ultrasound of the right kidney with the patient supine demonstrates a cystic lesion at its upper pole with hyperechoic material lying dependently within it (arrow). The material demonstrates moderate posterior acoustic shadowing with gravitational change evident on scanning in the prone position.

Figure 2

A 23-year-old female with recurrent urinary tract infection and right flank pain during pregnancy. (a) Transverse ultrasound image of the upper pole of the right kidney demonstrates layering echogenic material within an upper pole cystic structure (arrow). The echogenic material exhibited gravitational change on scanning the patient prone, confirming the diagnosis of a stone-bearing calyceal diverticulum. (b) Coronal tru fisp MRI demonstrates a calyceal diverticulum arising from an upper pole calyx (arrow); this observation correlates well with the ultrasound study. (c) T₂ weighted transverse MRI demonstrating high-signal calyceal diverticulum arising from the upper pole of the right kidney with low-signal areas (arrow) lying dependently within it in keeping with calculi.

Figure 3

A 47-year-old male with right flank pain. (a) A magnified view from a control film of an intravenous urogram (IVU) demonstrates a 2 cm opacity in the right upper quadrant (arrow). This image clearly shows that the opacity is made up of multiple tiny calculi rather than a single large calculus, which should raise the suspicion that they lie within a calyceal diverticulum. (b) An oblique radiograph from a retrograde pyelogram study elegantly depicts the short, narrow infundibulum of a calyceal diverticulum arising from a mid-pole calyx (arrow).

Figure 4

A 50-year-old female with left flank pain. (a) Two radiographs from an intravenous urogram (IVU) study: 20 min (left) and post-micturition (right). The images demonstrate contrast opacifying a lower pole calyceal diverticulum containing numerous calculi (arrow). Further opacification of the diverticulum is evident on the later film (right-hand image; arrow), highlighting the need for delayed images. Note that the infundibulum cannot be seen on either radiograph. (b) Coronal and transverse images from an MR urogram identify the lower pole calyceal diverticulum on the left side (arrow). Multiple areas of low signal are identified within the diverticulum and correspond to calculi (arrow).

Figure 5

A 35-year-old female who presented initially with flank pain and recurrent urinary tract infection. She had undergone several sessions of unsuccessful extracorporeal shock wave lithotripsy (ESWL) for a left upper pole renal calculus. The size of the left upper pole opacity remained unchanged on serial radiographs. (a) Non-contrast CT of the kidneys and (b) following intravenous contrast. Non-contrast CT demonstrates a cystic lesion at the upper pole of the left kidney with apparent mural calcification posteriorly (arrow). This could be mistaken for a complicated or indeterminate renal cystic lesion. However, following administration of intravenous contrast the low attenuation fluid within the cystic cavity when compared with the normally enhancing renal parenchyma confirms the presence of an upper pole calyceal diverticulum (arrow). Delayed imaging demonstrated layering of contrast material in the cavity of the diverticulum; this observation confirmed its connection to the collecting system (not shown).