S. Tzila Zwas

PET/CT in the evaluation of response to treatment of liver metastases from colorectal cancer with bevacizumab and irinotecan

The present approach at our institution for the treatment of patients with colorectal (CRC) cancer and with liver metastases planned for metastasectomy is the neoadjuvant administration of Bevacizumab with Irinotecan based therapy. Metabolic imaging of tumor viability with 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET), and simultaneous anatomic localization provided by low-dose non-enhanced computed tomography (CT), can be obtained in a combined modality FDG-PET/CT scan. The purpose of this study was to evaluate the possible contribution of FDG-PET/CT as a surrogate marker to evaluate treatment response of liver metastases in vivo. This is a retrospective evaluation of 18F-FDG PET and CT findings in the first seven consecutive patients. FDG-PET/CT scans were performed before the start of the neoadjuvant and after four cycles of therapy, just prior to surgery. Results were compared to concurrent contrast-enhanced CT, when required, and pathology. Response to treatment was determined according to RECIST size criteria obtained from data from thin (3–5mm) slice CT, and changes in uptake of 18F-FDG uptake on PET. A total of 20 liver lesions were evaluated in seven patients. Overall, 6/7 patients had favorable response to treatment, and only one had progression of disease. One patient was found to be inoperable at surgery. Biopsy was obtained in 1/4 lesions in this patient, while pathology was unable for the remaining three lesions. As such, pathologic validation of findings was available for 17/20 lesions. Complete response (CR) was evident on FDG-PET in 10/17 (58%) lesions, whereas only 4/17(23%) were deemed CR by CT. Similarly, only 1/17 (6%) lesion appeared stable by FDG-PET criteria, whereas three (18%) were termed stable disease (SD) according to size on CT. FDG-PET findings correlated better than CT with pathology, and were more indicative of pathology. Overall PET/CT correctly predicted necrosis at pathology in 70% vs. 35% by CT. Our results suggest that 18F-FDG PET may be instrumental for predicting the pathologic response to Bevacizumab based therapy.

Brain reactivity to specific symptom provocation indicates prospective therapeutic outcome in OCD.

A pertinent question in biological psychiatry is what differentiates responders and non-responders to pharmacological treatment. One possibility is that individual differences in the symptomatic spectrum as well as in the underlying biology of the disorder lead to the known 40% failure in pharmacological treatment. Our study aimed to maximize individual brain markers of obsessive-compulsive disorder (OCD) by applying single photon emission computed tomography (SPECT) during a provoked symptomatic state prior to and following treatment. Four brain SPECT scans were obtained from 26 OCD patients prior to and at 6 months of sertraline treatment. At each time point, two SPECT scans were performed in a counterbalanced order of two specific states; one a symptom-provoking condition and the other a relaxed condition. At 6 months of treatment, patients were divided into responders and non-responders according to a predetermined clinical criterion. Prospective responders showed significantly lower brain perfusion in the dorsal-caudal anterior cingulum and higher brain perfusion in the right caudate, when compared to non-responders, only during symptom provocation. When pre- and post-treatment scans during symptom provocation were compared, only responders showed significant change in brain response: increased perfusion in the left anterior temporal cortex and prefrontal cortex at 6 months treatment. These findings suggest that obtaining functional brain imaging during specific symptom provocation emphasizes individual differences in brain reactivity. Thus can indicate prospective responders to symptom-related treatment in OCD and mark the relevant brain regions for effective response to treatment.

131I ovarian uptake in a whole-body scan for thyroid carcinoma

A 20-YEAR OLD WOMAN, married and having two children, was first seen in March 1984. She was five months postsurgical removal of a left thyroidal nodule that was found to be a mixed papillary-follicular adenocarcinoma. She did not receive any further treatment. On physical examination she had no palpable neck masses. Her thyroidal laboratory blood tests revealed T4-radioimmunoassay (RIA) of 8.4 ~tg% (normal, 4.5 to 12.0 #g%) and thyroidstimulating hormone (TSH) of 5.2 #U/mL (normal, 0 to 4.0 ~tU/mL); namely, normal T4-RIA and borderline high TSH levels. A 24-hour 1311 thyroid uptake with a 5 #Ci dose was 22%. A 48-hour 1311 whole-body scan was performed after a dose of 0.5 mCi. This showed a normal right lobe with a residual left lower lobe. In the posterior left pelvis a rounded iodophilic concentration measuring 2 to 3 cm was noted (Fig 1). The patient returned to her home in another country after the examination and no further evaluation was obtained. Three years later she was seen again for a follow-up examination. She was not receiving any medication. Physical examination showed no neck changes, and she had been completely asymptomatic. Her laboratory blood tests remained unchanged from previous results. 1311 whole-body scans were performed two to seven days after a dose of 0.5 mCi. These scans showed no changes in the thyroid and neck regions. The iodophilic concentrations in the pelvic region persisted without any change in size or location. Since bone metastasis was a possibility, a bone scan was performed following an intravenous (IV) dose of 15 mCi 99mTc-methylene diphosphonate (MDP); it was negative for metastatic disease. On pelvic radiography a small irregularly shaped density was noted in the left lower quadrant in the plane of the lower sacrum. The configuration of the density was characteristic of a cluster of teeth. This finding was pathognomonic for a dermoid tumor (Fig 2). An ultrasound study of the pelvis revealed a left ovarian semisolid tumor measuring 3 x 4 cm containing

Occult aortic arch mycotic aneurysm diagnosed by radiogallium scintigraphy.

Aortic arch mycotic aneurysm, an uncommon cause of sepsis, carries a grave prognosis. Clinical presentations as well as laboratory and radiologic examinations may be noncontributory and often misleading. In a patient with a fever of unknown origin, only the radiogallium study could enable an accurate diagnosis and pinpoint the anatomic localization of the mycotic aneurysm as the cause of fever.

Combined Increased and Decreased Skeletal Uptake of F-18 Fdg

Increased uptake of F-18 FDG is the general mainstay of diagnosis, because it indicates hypermetabolic foci of pathology. This case, describing a patient with relapsing lymphoma, represents the diagnostic dilemmas of both locally decreased and diffusely increased uptake in the skeleton.

Unusual scintigraphic presentation of a shifting Meckel's diverticulum

A Tc-99m red blood cell (RBC) study in a child with acute gastrointestinal bleeding of unknown origin suggested Meckels diverticulum because of free pertechnetate uptake in the ectopic gastric mucosa. This finding has not been reported in the literature. A scan with Tc-99m pertechnetate then demonstrated a focal area of uptake with an unusual pattern of abdominal shifting consistent with a Meckels diverticulum. A large Meckels diverticulum containing gastric mucosa was found at surgery. A shifting pattern of focal uptake on a meckelogram study should be included among the diagnostic criteria for Meckels diverticulum.