A new technique is described that allows for the creation of pure pulsatile flow magnetic resonance (MR) images in a single acquisition. Five to 16 electrocardiographically gated images spanning the entire cardiac cycle are obtained with use of a gradient-echo pulse sequence. The section can be varied from 4 mm thick to full thickness projection. Taken singly, each image provides direct assessment of flow direction and velocity. Subtraction of image pairs eliminates signal detected from stationary protons, producing images of pulsatile flow. In this study the technique was used to image the flow of cerebrospinal fluid (CSF) in healthy subjects and in one patient with syringohydromyelia. The data suggest that multiphasic MR imaging provides a powerful means for the noninvasive assessment of CSF pulsatile flow dynamics and may have potential clinical application for the investigation of a variety of abnormalities such as normal pressure hydrocephalus, syrinx, and spinal block.

A collection of milk of calcium in a caliceal diverticulum is an unusual finding with benign clinical implications. Only one case' has been reported demonstrating the sonographic features of milk of calcium in a caliceal diverticulum, although the conventional urographic appearance has been well documented. We have added a second case which confirms the previously described sonographic findings of gravity-dependent, echogenic, shadowing material in a cystic renal lesion. Our case is unique in that we discovered bilateral caliceal collections of milk of calcium. The literature on milk of calcium is briefly reviewed. CASE REPORTA 25-yr-old woman presented to the Massachusetts General Hospital with right upper quadrant pain and a temperature of 100.4"F. On physical examination, there was right upper quadrant pain but no flank tenderness. The leukocyte count was 11,400, with no left shift. The laboratory chemistry values of Ca2+, PO4, blood urea nitrogen, creatinine, bilirubin, serum glutamic-oxaloacetic transaminase , and serum glutamic-pyruvic transaminase were normal. On urinalysis, a few amorphous crystals were noted in the sediment. There was no pyuria, bacteriuria, or hematuria. Urine cultures were negative. The pH was 6.5, and the specific gravity was 1.009.A preliminary film of the abdomen revealed opacifications in the right and left upper quadrants overlying the renal shadows, suggesting calculi. On the upright film, the calcifications formed a linear collection on the right and a meniscus-like "half-moon" collection on the left, (Fig 1A). An oral cholecystogram showed good opacification of the gallbladder and no evidence of stones.Abdominal ultrasound examination was performed using an ATL scanner* with a 3.5-MHz transducer. The supine real-time scans demonstrated right and left upper pole cystic lesions with enhanced through transmission. There were gravity-dependent, dense internal echoes with minor acoustic shadowing (Fig lC, D). On nephrotomography, the lesions did not opacify ( Fig 1B).The patient's symptoms resolved after two days, and she was discharged without a diagnosis of her right upper quadrant pain. DISCUSSIONThe sonographic appearance of milk of calcium within a caliceal diverticulum was first reported by Schabel et all in 1980. Our case confirms his findings of gravity-dependent echogenic material in a cystic renal lesion with low-grade shadowing. Although a reasonable differential diagnosis might include calculi within a hydrocalyx, the sonographic features of this entity appear diagnostic.The radiographic manifestations of milk of calcium in a caliceal diverticulum were first discussed by Fresnais2 and described in the English literature by H~w e l l .~ Characteristically, a meniscus or calcium-fluid level is seen on horizontal beam projections but is not appreciated en face. Since ultrasound has a well-documented capacity to image renal cystic lesions and stones surrounded by fluid, it should also be sensitive in diagnosing this condition.milk of calcium occurred with equal frequency i...

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