Hadyn T. Williams

Incidental PET/CT findings in the cancer patient: How should they be managed?

BACKGROUND Despite a paucity of evidence-based guidelines, the use of PET/CT (positron emission tomography/computed tomography) in the management of cancer patients is increasing. As widespread clinical application increases, unexpected radiographic findings are occasionally identified. These incidental findings are often suspicious for a second primary malignancy. The purpose of this study was to determine the clinical impact of these incidental PET/CT findings. METHODS A query of our prospectively acquired Nuclear Medicine database was performed to identify patients with a known malignancy being staged or serially imaged with PET/CT. Patients with incidental findings suggestive of a second primary malignancy were selected. Statistical analysis was performed to determine the ability of PET/CT to identify a second primary malignancy. All PET/CT were interpreted by board certified nuclear radiologists. RESULTS Of 3,814 PET/CT scans performed on 2,219 cancer patients at our institution from January 1, 2005, to December 29, 2008, 272 patients (12% of all patients) had findings concerning for a second primary malignancy. An invasive work-up was performed on 49% (133/272) of these patients, while 15% (40/272) had no further evaluation due to an advanced primary malignancy. The remaining 36% (99/272) had no further evaluation secondary to a low clinical suspicion determined by the treating team, a clinical plan of observation, or patients lost to follow-up. Of the 133 patients evaluated further, clinicians identified a second primary malignancy in 41 patients (31%), benign disease in 62 patients (47%), and metastatic disease from their known malignancy in 30 patients (23%). The most common sites for a proven second primary malignancy were: lung (N = 10), breast (N = 7), and colon (N = 5). Investigation of these lesions was performed using several techniques, including 24 endoscopies (6 malignant). A surgical procedure was performed in 74 patients (29 malignant), and a percutaneous biopsy was performed on 34 patients (12 malignant). The overall positive predictive value for PET/CT to detect a second primary malignancy was 31% in this subgroup. At a median follow-up of 22 months, 9 of 41 patients with a second primary were dead of a malignancy, 20 were alive with disease, and 12 had no evidence of disease. CONCLUSION Incidental PET/CT findings consistent with a second primary are occasionally encountered in cancer patients. In our data, approximately half of these findings were benign, a third were consistent with a second primary malignancy or a metastatic focus, and the remainder were never evaluated due to physician and patient decision. Advanced primary tumors are unlikely to be impacted by a second primary tumor suggesting that this subset of patients will not benefit from further investigation. Our data suggests that, despite the high rate of false positivity, incidental PET/CT findings should be investigated when the results will impact treatment algorithms. The timing and route of investigation should be dictated by clinical judgment and the status of the primary tumor. Further investigation will need to be performed to determine the long-term clinical impact of incidentally identified second primary malignancies.

Identification of distant metastases with positron-emission tomography-computed tomography in patients with previously untreated head and neck cancer.

Objectives: To investigate the utility of positron–emission tomography‐computed tomography (PET‐CT) in identifying distant metastatic disease in patients with previously untreated head and neck squamous cell cancer (HNSCC) prior to definitive treatment.

Revisiting the role of positron-emission tomography/computed tomography in determining the need for planned neck dissection following chemoradiation for advanced head and neck cancer†

Planned neck dissection following chemoradiation (CR) has been advocated in patients with head and neck squamous cell cancer (HNSCC) with advanced nodal disease and a clinical complete response to CR because of the potential for residual occult nodal disease. The utility of positron‐emission tomography/computed tomography (PET‐CT) in identifying occult nodal disease in this scenario is controversial.

Identification of distant metastases with PET-CT in patients with suspected recurrent head and neck cancer

To investigate the utility of positron‐emission tomography/computed tomography (PET‐CT) in identifying distant metastatic disease in patients with suspected recurrent head and neck squamous cell cancer (HNSCC).

The predictive value of incidental PET/CT findings suspicious for breast cancer in women with non-breast malignancies

BACKGROUND On occasion, patients followed with positron emission tomographic (PET)/computed tomographic (CT) imaging for nonbreast malignancies will have incidental breast findings concerning for second primary breast cancers. The aim of this study was to determine the predictive value of PET/CT imaging to identify breast cancers in these patients. METHODS Patients with primary nonbreast malignancies and findings concerning for second primary breast cancers were identified from a prospectively acquired nuclear medicine database from January 2005 to July 2008. Chart reviews were then performed. RESULTS Nine hundred two women underwent PET/CT imaging to evaluate nonbreast malignancies. Nine women (1%) had concerning breast findings, and 5 (56%) had subsequent breast cancer diagnoses. The positive predictive value of PET/CT imaging in these patients was 63%. Evidence of compliance with current screening guidelines was present in only 22% of these patients. CONCLUSIONS The data suggest that findings concerning for an additional primary breast cancer should be evaluated and that age-appropriate screening tools should not be abandoned.

Utility of 18F-FDG PET/CT in identifying penile squamous cell carcinoma metastatic lymph nodes

OBJECTIVES Due to the significant potential morbidity of inguinal and pelvic lymphadenectomy, the search for an imaging modality that can accurately identify penile squamous cell carcinoma (SCCA) lymphatic metastases continues. Initial (18)F-FDG PET/CT studies have reported 80% sensitivity and 100% specificity in the detection of inguinal and obturator lymph node metastasis. We review a single institutional experience of (18)F-FDG PET/CT imaging of SCCA of the penis to assess for accuracy and potential impact on clinical management. METHODS Three patients diagnosed with penile SCCA at a single institution underwent staging (18)F-FDG PET/CT and went on to subsequent inguinal lymph node dissection. The (18)F-FDG PET machine was a Philips Gemini Time-of-Flight PET with LYSO crystals with 4.7 mm spatial resolution. The CT was a 16-slice helical CT with 5 mm slice widths. (18)F-FDG PET/CT findings were compared with the histologic findings of these procedures. Decision to proceed with lymphadenectomy was based on clinical judgment of a single urologist and all fused (18)F-FDG PET/CT imaging was assessed by a single experienced radiologist. RESULTS No patient received chemotherapy or radiation before the (18)F-FDG PET/CT or surgery. The first patient was obese (BMI > 30), clinically node negative, and the (18)F-FDG PET/CT showed inflammation. Histologic examination showed a positive 2 cm right inguinal metastatic node. The second patients (18)F-FDG PET/CT showed a suspicious 1 cm left inguinal node. Histologically, the suspicious lymph node was positive for SCCA as was a second positive 2 cm lymph node not identified on preoperative (18)F-FDG PET/CT. Clinical exam of this patient was negative. The third patient was (18)F-FDG PET/CT and clinically negative but subsequently developed a palpable lymph node approximately 1 month later, which was suspicious on repeat (18)F-FDG PET/CT and positive for SCCA on histological examination. CONCLUSIONS (18)F-FDG PET/CT has shown initial promise in the staging of penile SCCA. However, our review shows that false negative studies occur at alarmingly high rates, and (18)F-FDG PET/CT is poor in detection of micro-metastasis. Thus, close follow-up in these patients is imperative.

Imaging of Gastrointestinal Bleeding

Radiological techniques are important in evaluating patients with gastrointestinal bleeding. Scintigraphic, computed tomographic angiographic, and enterographic techniques are sensitive tools in identifying the source of bleeding and may be useful in identifying patients likely to have a benign course and in selecting patients for therapeutic intervention. Angiography plays a key role in bleeding localization, and modern embolization techniques make this a viable therapeutic option. With the refining developments in body imaging and related reconstructive techniques, it is likely that radiological interventions will play an expanding and critical role in evaluating patients with gastrointestinal hemorrhage in the future.

Multicentric giant cell tumor of bone.

Results: The male:female ratio was 1:2, with an average age at presentation of twenty-one years. Fifty-nine percent of the patients were younger than twenty years of age. There were ninety-four tumors in the series, with an average of three (range, two to nine) per patient. Most tumors had arisen in the long bones. Six patients had synchronous ipsilateral involvement of the distal part of the femur and the proximal part of the tibia. Radiographically, the tumors in long bones manifested as expansive lytic lesions involving the metaphysis and extending into the epiphysis. A minority of the tumors were confined to the metaphysis, had features of a fibro-osseous or bone-forming lesion, or arose in skeletally immature patients. Secondary histopathologic changes including fibrohistiocytic regions, reactive bone formation, or aneurysmal bone cyst-like changes were not uncommon. Most tumors were treated with curettage (64%) or resection (22%). The recurrence rate was similar to that of solitary giant cell tumors. Metastatic disease developed in three patients, and two patients had malignant transformation.

Diagnosis of pheochromocytoma in the setting of Parkinson disease

Background. A 59-year-old man with a 7-year history of Parkinson disease (PD) presented with episodes of sudden, severe headaches with neck pain, tachycardia, sweating and pallor. During these episodes, the patient showed marked elevations in blood pressure, regardless of posture. This was unusual, given that he had no prior history of hypertension. The array of symptoms raised suspicions of pheochromocytoma, but diagnosis was challenging, as the standard diagnostic biochemical tests were confounded by dopaminergic medications. Further work-up revealed left adrenal medullary hyperplasia. Several reports exist of pseudopheochromocytoma in patients on dopaminergic therapy, but this is the first documented case of pheochromocytoma syndrome due to adrenal medullary hyperplasia in a patient with PD. This case highlights the challenges of performing a diagnostic work-up in a PD patient with symptoms suggestive of pheochromocytoma, and illustrates the utility of 123I-metaiodobenzylguanidine (123I-MIBG) single-photon emission CT in making a diagnosis.Investigations. Physical examination, laboratory tests, abdominal MRI scan, abdominal 123I-MIBG scan, abdominal 18F-fluorodeoxyglucose PET scan.Diagnosis. Pheochromocytoma syndrome due to adrenal medullary hyperplasia.Management. Surgical excision of the left adrenal gland.

Indium 111 Diethylenetriamine Pentaacetic Acid Scintigraphy in the Identification and Management of Intrathecal Pump Malfunction

Intrathecal drug‐delivery systems have become widely used tools in the management of refractory chronic pain and spasticity. Because increasing numbers of patients are using these systems, rehabilitation specialists frequently are the initial care providers who identify clinical signs and symptoms indicating possible complications relating to the implanted system. Identification of a pump malfunction often presents a diagnostic challenge. Distinguishing among progression of disease, new organic problems, and/or drug‐device complications is critical. The use of nuclear medicine indium 111 diethylenetriamine pentaacetic acid (DTPA) studies represents a highly effective, straightforward, minimally invasive way to assess implant function and drug distribution.