The idea that assessment is intrinsic to effective instruction is traced from early experiments in the individualization of learning through the work of Benjamin Bloom to reviews of the impact of feedback on learners in classrooms.
Incidental hypervascular lesions are also very common findings in liver imaging. It is important to differentiate between 'touch' and 'don't touch' lesions. Benign 'don't touch' hypervascular tumors include hemangioma, FNH and small adenomas.
Carcinoid, islet cell metastases, and metastases from a leiomyosarcoma are also hypervascular, but to a lesser degree. When liver metastases are hypovascular relative to the liver, the tumors stand out as avascular defects in the capillary phase of the hepatic angiogram (hepatogram phase). If the hypovascular metastases are multiple, the hepatogram phase of the liver resembles Swiss cheese.