Prof. Jacob Valk, PhD.
Renowned neuroradiologist Prof. Jacob Valk, PhD, died on 13 April at the age of 94 in Wilnis, a village in the Dutch province of Utrecht. He was a world expert on pediatric neuroimaging, inborn errors of metabolism, toxic encephalopathies, and white matter disorders in dementia.
For nearly 20 years, Valk was a professor of radiology and neuroradiology, and head of the Departments of Radiology and Neuroradiology at Vrije Universiteit Medical Centre, the Netherlands. After his retirement, he worked as a neuroradiologist at the MRI Center in Amsterdam.
Valk became an honorary member of the RSNA in 2003.
"Jaap Valk has excelled in the fields of neurology, psychiatry, and neuroradiology. He published a medical book every year during the middle of his career. His writings include seminal concepts on such topics as white matter disease of the brain," noted RSNA 2003 President Dr. Peggy J. Fritzsche. "He is a Renaissance man, publishing in both the arts and sciences. He is a talented pianist who has entertained many of us with his regalia of show tunes and classical pieces. He is still actively contributing, as a writer and teacher."
Valk wrote more than 220 articles and book chapters, as well as 16 books, including Magnetic Resonance of Myelin, Myelination and Myelin Disorders, a standard text in the field.
In an announcement, Edith M. de Boer described him as “erudite, creative, a gifted pianist, generous, inspirational, funny, pleasantly disturbed, an experienced world traveler, and diver.”
A farewell meeting will be held on Saturday 20 April at noon at the Crematorium Westgaarde in Amsterdam. Afterward, there will be an opportunity for attendees to meet each other in the reception room, the announcement noted. Also, the next issue of MemoRad, the Dutch radiology magazine, will feature a tribute article written by Prof. Jonas Castelijns, Prof. Frederik Barkhof, and Dr. Paul Algra.

![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnieeurope.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&fit=crop&h=100&q=70&w=100)






![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnieeurope.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&fit=crop&h=112&q=70&w=112)









