dynamic contrast-enhanced imaging.^37 Other perfusion-weighted MR imaging
techniques include dynamic T1-weighted contrast imaging (providing assessment
of tumor permeability) and arterial spin labeling (a perfusion technique that uses
intraarterial water as an endogenous tracer, and it does not require administration of
intravenous gadolinium). Perfusion-weighted MR imaging is a promising tech-
nique, but it is less widely available in its use and at present is limited to a few
centers.^38 On the other hand, diffusion-weighted imaging (DWI) has found various
applications in head and neck imaging, especially in the differentiation of benign
and malignant processes, in salivary gland tumors and xerostomia evaluation, as
well as in prediction and monitoring of response to nonsurgical therapy. One of the
major clinical applications of DWI is the assessment of tumor recurrence in
posttherapy setting. Posttherapy mass and recurrent tumor can be differentiated to
some extent by DWI. Recurrent tumors show decreased apparent diffusion coeffi-
cient (ADC) values compared with nonmalignant changes or radionecrosis, pre-
sumably due to increased free water in necrosis and increased cellularity in
recurrent tumors.^39 While there is no single ADC value or a range of ADC values
that can diagnose recurrent tumor with certainty, these values can increase the
confidence that the lesion is probably not recurrent tumor. Molecular imaging
provides information on metabolic characteristics of detected lesion. FDG
PET/CT imaging is a well-established method for the assessment of glucose uptake
and intracellular phosphorylation in different tissues/organs within the body, but
novel tracers for the assessment of tumor proliferation and measurement of amino
acid transportin vivo, imaging tumor hypoxia, and gene expression have been
developed.^40 PET/CT with flourine 18L-thymidine (FLT) as a cell proliferation
tracer enables early assessment of tumor response to single-dose image-guided
radiation therapy.^41 For many cancers, the treatment is already being targeted not
only to the tumor type and stage but also to the tumor biology and its molecular
pathways.^42 Imaging provides detailed information on the tumor size and invasion
of adjacent organs and tissues that is essential for the assessment of its resectability.
Endorectal MRI provides accurate information and significantly improves the
surgeon’s decision to preserve or resect a neurovascular bundle during radical
retropubic prostatectomy in order to avoid positive surgical margins, but preserve
erectile function, when possible.^43 The extent of cerebral neoplasm resection is
believed to be a crucial prognostic factor in improving patient survival. Surgical
treatment of cerebral neoplasms intends to maximize the extent of neoplasm
resection while reducing the loss of normal brain tissue. The anatomical position
(^37) Srinivasan et al. ( 2012 ).
(^38) Lacerda and Law ( 2009 ).
(^39) Ludemann et al. ( 2009 ) and Vandecaveye et al. ( 2007 ).
(^40) Crommelin et al. ( 2011 ).
(^41) Abdel Razek et al. ( 2007 ).
(^42) Abdel Razek et al. ( 2007 ).
(^43) Hricak ( 2011 ).
226 D. Miletic ́et al.