Leo George Rigler (1896 - 1979)

Leo George Rigler (1896-1979) was an American radiologist.

Worked with the World Health Organization to improve clinical radiology in developing countries including India, Iran and Israel. Published over 200 articles and edited six books

Rigler was the first to point out that the decubitus position was very useful in the diagnosis of small pleural effusions of as little as 100mL of fluid. Eponymously affiliated with Rigler sign; Rigler triad, Rigler notch sign and Hoffman-Rigler sign

  • Born on October 16, 1896, in Minneapolis
  • 1920 – MD, University of Minnesota
  • 1934 – certified by the American Board of Radiology (68th member)
  • 1937 – chairman of radiology at the University of Minnesota (held until 1957)
  • 1963 – professor of radiology at the University of California
  • Died on October 25, 1979

Medical Eponyms
Rigler sign (1941)

Radiographic sign of pneumoperitoneum. Air in the peritoneum and air within the intraluminal spaces outline the luminal and serosal surfaces of the bowel wall.

Rigler triad (1941)

Imaging findings in patients with gallstone ileus:

  • an ectopic gallstone causing
  • partial or complete small bowel obstruction, and
  • pneumobilia and/or gallbladder lumen gas
Rigler triad gallstone ileus Radiopaedia 3

Rigler triad: 1. pneumobilia; 2. small bowel obstruction; 3. ectopic calcified gallstone
Case courtesy of Assoc Prof Frank Gaillard. Case rID: 6906

Rigler notch sign (1955)

Indentation in the border of a solid lung mass (thought to represent a nutrient/feeding vessel) and is suggestive of a bronchial carcinoma.

The sign is not pathognomonic of bronchial carcinoma being observed in other conditions, such as granulomatous infections. The sign as a differentiating utility is limited.

Rigler and Heitzman describe the notches pathologically and histologically.

In many histologic section of this small lesion shows an area of blood vessels surrounded by alveoli which is drawn into one side of the tumour. It is possible that the tumour has grown around this stalk, thus resembling the hilus of an organ.

Rigler and Heitzman, Radiology 1955
Rigler notch sign pathology and histology

Fig. 8. Notch sign in a hypernephroma metastasis. A. Planigram showing large nodule in lung with marked indentation on lateral border, fairly characteristic of notch sign. B. Surgical specimen showing a deep groove (arrows) in the tumor corresponding to the notch. C. Microscopic section showing alveoli and blood vessels extending into the margin of the tumor. Radiology 1955

Hoffman-Rigler sign (1965)

Radiological sign of left ventricular enlargement based on the distance between the inferior vena cava (IVC) and left ventricle (LV).​

On a lateral chest radiograph, if the distance between the left ventricular border and the posterior border of IVC exceeds 1.8 cm, at a level 2 cm above the intersection of diaphragm and IVC, left ventricular enlargement is suggested.

Hoffman-Rigler sign measured
Hoffman and Rigler index measurement (A).

** Richard Bashefkin Hoffman (1937-2011) and Rigler described their eponymous sign in 1965

Major Publications



Eponymous terms


Andrew Warnock LITFL Author 2

Third year M.D. student at the University of Notre Dame Fremantle. Passionate about emergency and retrieval medicine, rural practice and clinical research

BA MA (Oxon) MBChB (Edin) FACEM FFSEM. Emergency physician, Sir Charles Gairdner Hospital.  Passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |

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