The ‘Faschingskrapfen,’ also known as ‘Berliner Pfannkuchen’ is a round, fried pastry, similar to a jelly doughnut. These delicious treats are generally served during the German Mardi Gras, ‘Fasching.’ As a playful joke, the inside of the pastry is sometimes filled with mustard instead of jelly or pudding, making for a great surprise during the first bite. After all, outside appearances aren’t always as they seem. Luckily, Dominik Morhard, MD, and his colleagues at the Department for Clinical Radiology at the University Hospital in Munich have found a solution for this problem.¹ Through the efficient implementation of computed tomography (CT) and 3-Tesla magnetic resonance imaging (MRI), four Krapfen were tested in order to determine their inside contents. The goal of the examination was clear: Where is the pudding, where is the mustard, and where is the jelly?

The four doughnut-like pastries received different names depending on their filling: PK represented the Krapfen filled with pudding, MK the one holding the jelly. S1K held sweet mustard, S2K spicy mustard.
First, an analysis with the two 3-Tesla MRI systems MAGNETOM^® Verio and MAGNETOM Trio was performed. Morhard describes: “Alongside their short axes, they were positioned on top of each other in an 8-channel headcoil. Two customary 20 ml plastic syringes filled with H2O (30° C) were positioned left and right of the Krapfen in the head coil as reference and to increase the coil load.”
Before the pastries could go into their original destination they had to undergo the screening in a SOMATOM^® Definition CT scanner. “After reconstruction with 80 kV, 140 kV and weighted mixed images analogue to 120 kV measurements, the acquired data was transferred to a standard workstation (syngo^® MMWP E 25 A) and reconstructed,” the radiologist explains.

In many ways, the PK or pudding pastry stood out from its fellow pastries. Using 3T MRI it was the only one that showed low signal intensities during T1-weighted imaging, so long T1 relaxation times. In the Dual-Source CT scanner, it was the only Krapfen with negative density values. Hence it looked clearly different than the others.
In contrast to PK, the density values of the jelly-filled Krapfen were positive. Unlike PK and MK, the mustard-filled Krapfen showed positive Dual Energy characteristics. These characteristics refer to the energy dependency of the x-ray absorption for each filling.
The sweet filling of S1K showed an irregular interior structure with signal extinctions near the mustard seeds, as Morhard explains. This way, S1K and its spicy brother S2K were distinguishable.
Now Krapfen lovers know where to turn to – the radiologists at Munich’s University Hospital – when faced with the risk of biting into a mustard-filled pastry. There, falsely filled pastries don’t stand a chance.