Biomedical Research Foundation of Northwest Louisiana

Salivary duct carcinoma (SDC) is a rare and extremely aggressive salivary gland cancer. An 81-year-old woman with SDC underwent a total parotidectomy with facial nerve sacrifice and a neck dissection. Following surgery, she was diagnosed with disseminated bone marrow metastases. She underwent chemotherapy and trastuzumab for palliation. We present a case of SDC of the parotid which was diagnosed with disseminated bone marrow metastasis following surgery for the primary. This case also highlights the importance of having a high index of suspicion while evaluating highly aggressive tumours like SDC for any atypical findings during workup.

The early detection of persistent/recurrent disease of head and neck squamous cell carcinoma (HNSCC) after treatment can be challenging. The currently used radioisotope (18)F-fluorodeoxyglucose (FDG) is a nonspecific tracer for cancer cells as it detects all metabolically active cells including inflammation. (18)F-fluorodeoxythymidine (FLT) is a radioactive tracer for rapidly proliferating cells, and therefore is more specific for detecting cancer. Our aim was to compare FLT and FDG microPET (positron-emission tomography) to the gold standard in vivo bioluminescence imaging for serial assessment of neoplastic growth in a minimal residual disease in vivo model. Prospective outcomes research. In order to mimic the postsurgical environment of HNSCC patients FaDu cells transfected with a luciferase-expressing retrovirus were inoculated into the skin flap of Balb/c nu/nu mice. Three days later before tumors formed, mice were randomized into (18)F-FLT or (18) F-FDG groups, and microPET imaging was performed on days 3, 6, 10, 18, and 24 after tumor cell inoculation. (18)F-FLT detected tumors as early as day 3 even before tumors were palpable, whereas (18)F-FDG only detected palpable tumors. The average overall normalized radioactivity in the FLT group was significantly higher than the FDG group (P = .025). (18)F-FLT identified tumor cells before tumors were palpable and can potentially be used for early detection of persistence/recurrence of HNSCC. In addition, this radioisotope can be used to monitor adjuvant therapy with novel targeted therapeutics in preclinical models of persistent disease.

We report a case of a patient with brain metastases and simultaneous Alzheimer disease (AD) on FDG-PET imaging. Literature documenting AD coexisting with brain metastases is extremely rare, and there are no previously documented cases of FDG-PET imaging revealing concurrent AD and brain metastases. In addition to AD, both brain metastases and whole-brain radiation therapy may cause neurocognitive deterioration. Hence, it is important to differentiate the underlying pathologic process that is causing dementia in patients with brain metastases, to better manage these patients and improve their quality of life.

Fluorine-18 fluorodeoxyglucose positron emission tomography was obtained in a patient with a duodenal mass. Conventional imaging revealed multiple dilated intestinal loops. Initial impression of positron emission tomographic images was interposition of a loop of bowel between the liver and diaphragm (Chilaiditi syndrome) in an unusual location, with absent right kidney activity. Computed tomography and magnetic resonance imaging of the abdomen showed an obstructed ectopic kidney in this position with a markedly dilated collecting system. There is absence of fluorodeoxyglucose in the markedly dilated renal collecting system resulting from acute obstruction, giving the false appearance of gas-filled bowel loops with an unusual location of the interposition.

Any novel technological innovation is dependent more on the ingenuity of its users than its inherent properties and potential flaws. Positron emission tomography (PET) is unique in this regard because the limitations of this modality are defined by the ability of its users to identify tracers that will aid in the diagnosis of intracerebral processes. The limitations of PET scanning lay in the extent of tissue resolution and in the currently relatively small number centers equipped to perform PET scanning. In this issue of Neurosurgical Focus, various applications of PET scanning are detailed. The traditional use of this technology in neurosurgery has been to determine the metabolic nature of cerebral neoplastic lesions so as to help differentiate neoplastic from benign or infectious processes. This determination, however, has not been foolproof, and the technique has been further refined to maximize diagnostic yield. Nonetheless, the utility of PET scanning continues to grow. New applications have allowed for the precise measurements of cerebral blood flow, helping the neuroscientist understand the functional organization of cortex, the pathophysiology of normal-pressure hydrocephalus, and changes in cerebral blood flow following traumatic injury. Other radiotracers such as fluorodopa allow assessment of the metabolic state of cerebral tissue transplants in restorative neurosurgical procedures. In this introduction, all of these issues will be considered, and a historical perspective and the potential future uses of this technology will be provided. Technology moves so quickly that new instruments are routinely introduced. The authors will try to assess what properties, in the 25-year history of PET scanning, will need to be improved to keep it as a cutting-edge technology and expand its clinical role.