Whole-body positron emission tomography using fluorodeoxyglucose in patients with metastases of unknown primary tumours (CUP syndrome)

The aim of this study was to evaluate the clinical performances of whole body 2-[18F]fluorodeoxyglucose positron emission tomography (FDG PET) imaging for the detection of the primary tumour in patients with metastases of unknown origin. Forty-one patients, without previous history of known cancer (18 women and 23 men; average age 64.1 years) with metastasis confirmed by histopathological analysis were included in a retrospective study. Results of PET were compared with those of techniques used in the current conventional diagnostic procedure. All known metastatic lesions were detected by PET. There were 26 true-positive and two false-negative results. Primary tumour remained undetermined in eight patients after conventional investigations and PET. PET was superior to conventional diagnostic procedure in 11 patients and led to modify treatment in 11 patients. Sensitivity of PET was superior than computed tomography in detecting abdominal primary tumours. FDG PET is useful in patients with unknown primary tumour because its sensitivity is good and it could modify the disease management. Otherwise, PET allows the evaluation of the extent of the disease and could be used to monitor treatment efficiency. Its contribution has to be evaluated particularly in patients with primary tumour with a specific treatment.     

Computed tomography of calcified liver metastases.

The computed tomography findings of six patients with calcified liver metastases are presented. The significance of this finding in patients with unknown primary malignancies or after multiple courses of chemotherapy is stressed.     

Hepatic venography in the surgical assessment of hepatic tumours

Hepatic venography was performed on 80 patients with hepatic tumours for the pre-operative assessment of resectability. Sixty-six patients subsequently underwent laparotomy, 27 undergoing hepatic resection. Forty-two patients had metastases from colo-rectal primaries, 19 hepatocellular carcinoma and 19 a variety of other tumours. The type and frequency of the abnormalities shown on venography were noted for each tumour category and for their hepatic segmental distribution. The results of venography were compared with those of arteriography, computed tomography and ultrasound and with the findings at laparotomy. Displacement was the commonest abnormality seen while encasement or obstruction occurred less frequently and tumour invasion was rare. The sensitivity of venography in correctly identifying the segmental distribution of tumour deposits was 41%. Sensitivity was poorest with tumours in the left lobe (31%) and bilobar tumours (0%). Venography was most sensitive in detecting tumour involvement of the major segmental hepatic veins and inferior vena cava (100%). Peripheral colo-rectal metastases frequently produced no venographic abnormality. Hepatic venography provides no additional information to arteriography, computed tomography or ultrasound in patients with peripheral or bilobar tumour deposits. Some additional information may be obtained with central tumours and venography is the most accurate means of detecting tumour involvement of the major segmental hepatic veins.     

Ultrasound and computed tomographic findings in pancreatic metastases

This is a retrospective study of a series of seven patients with pancreatic metastases studied by ultrasonography and computed tomography. They were detected during tumor staging, or in the follow-up period of over 10 years of patients with advanced known malignancy. Lesions were multiple in two patients and solitary in five; solid in six cases and cystic in one. Clinically, four cases were asymptomatic and three cases presented with jaundice or epigastric pain. Ultrasonography and computed tomography findings were non-specific. Consequently it was not possible to differentiate solitary metastases from primary solid adenocarcinoma and cystadenocarcinoma of the pancreas. In these cases, computed tomography- or ultrasonography-guided biopsies had to be performed to obtain histological proof. However, multiple lesions discovered in a patient with a known malignancy can be assumed to be due to metastases.     

Imaging of primary non-Hodgkin's lymphoma of the liver

AIM: To describe the radiological findings in primary liver lymphoma, which is a rare entity, presenting usually as a localized liver mass. MATERIALS AND METHODS: We reviewed retrospectively the imaging findings at presentation, of patients in whom a diagnosis of primary liver lymphoma was finally made histologically. The study period covered a 10-year period between January 1990 and December 1999. There were seven patients, all men, with a mean age of 49.6 years. Each patient presented with hepatobiliary disease without peripheral adenopathy. Imaging prior to diagnosis included ultrasonography (seven patients), computed tomography (seven patients) and magnetic resonance imaging (MRI) (two patients). Appearances during and after aggressive chemotherapy were reviewed. RESULTS: Imaging appearances were of either single or multiple liver lesions simulating liver metastases. On ultrasound all foci of primary hepatic lymphoma (PHL) were hypoechoic relative to normal liver. Computed tomography (CT) showed hypoattenuating lesions in all cases, and two cases showed rim enhancement following contrast administration. The MRI appearances were variable, and no pathognomonic feature of PHL was identified, so that histology was required in all patients to establish the diagnosis. CONCLUSIONS: This paper demonstrates the spectrum of findings encountered on various imaging modalities in PHL. We conclude that although PHL is a rare condition, it should always be considered in the differential diagnosis of liver metastases when no primary tumour is apparent.     

Detection of unknown primary tumours and distant metastases in patients with cervical metastases: value of FDG-PET versus conventional modalities

In 1%-2% of head and neck oncology patients, the only symptom of a malignancy is a positive cervical node. The aim of this study was to compare the value of positron emission tomography using fluorine-18 fluoro-2-deoxy- D-glucose (FDG-PET) and conventional diagnostic modalities (CT and/or MRI, panendoscopy) in detecting unknown primary tumours and distant metastases in patients suffering from such a cervical metastasis. Fifty patients (37 men and 13 women) with cervical metastases of an unknown primary tumour were included. All patients underwent FDG-PET. In addition, CT and/or MRI was obtained and panendoscopy was performed. All clinically known metastases were detected by FDG-PET. The primary tumour could be diagnosed in 16 patients (four primary tumours were detected exclusively by FDG-PET). Seven patients had multiple distant metastases, that in six cases were detected exclusively by FDG-PET. The sensitivity and specificity of FDG-PET for detection of unknown primary tumours were 100% and 94%, respectively. For the conventional diagnostic modalities these values were 92% and 76%. FDG-PET had an exclusive effect on the applied therapy in 20% of the patients referred for diagnosis of an unknown primary tumour. The data obtained in this study strongly support the diagnostic strategy of performing FDG-PET in patients suffering from cervical metastases of an unknown primary tumour before any other diagnostic technique.     

Thin-section computed tomography of intrapulmonary metastases after surgical resection of lung cancer

To evaluate the morphology of small peripheral intrapulmonary metastases of lung cancers, we studied thin-section computed tomography (CT) images of 12 lesions in 5 cases (1 squamous cell carcinoma, and 4 papillary adenocarcinomas). All lesions were resected, and histopathological diagnosis of them was performed in comparison with primary lesions to differentiate multiple primary lung cancers from intrapulmonary metastases. Thin-section CT images showed mildly lobulated nodules in connection with supplying pulmonary vessels, however, indented pleura and vascular convergence were less frequently seen in intrapulmonary metastases in contrast with primary lung cancers. Thin-section CT is helpful for distinguishing multiple primary lung cancers from intrapulmonary metastases in patients with a history of surgical resection for lung cancers.     

Mimics of metastases from testicular tumours

This paper presents 10 patients with a diagnosis of testicular tumour in whom computed tomography (CT) at staging or follow-up demonstrated abnormalities which mimic the appearance of metastatic testicular tumour. The entities mimicking metastases were sarcoidosis, mushroom worker's lung, lymphoma and phaeochromocytoma. Representative examples of these lesions are illustrated and features which may enable the radiologist to differentiate them from metastatic testicular tumour are discussed.     

Accidental finding of a giant retroperitoneal lipoma in a traumatic rupture of the renal parenchyma

With a rate of 0.1-3% of all tumour cases primary retroperitoneal neoplasms are very rare. Malignant tumours predominate. Preoperative radiological clarification as regards tumour status is very unsafe unless there are indications of infiltrating growth and metastases. In some cases, computed tomography can supply pointers to the kind of the tumour.     

In search of an unknown primary tumour presenting with cervical metastases: performance of hybrid FDG-PET-CT

OBJECTIVES: In patients with cervical lymph node metastases from unknown primary tumour (UPT), the primary tumour is frequently localized in the head and neck area. Because the detection of the primary tumour is of importance to optimize the patient's management and allows a targeted therapy, the performances of hybrid positron emission tomography-computed tomography (PET-CT) using fluorodeoxyglucose (FDG) were evaluated in a retrospective study. METHODS: Thirty-eight consecutive patients with cervical lymph node metastases, and in whom the primary was not detected by the comprehensive diagnostic work-up including endoscopy and conventional imaging methods, were referred for a PET-CT scan. RESULTS: PET-CT was positive with an increased FDG focal uptake suggesting the potential primary site in 68% of patients (26/38), which guided the biopsies during a second rigid panendoscopy in 17 of these 26 patients: 13 primary tumours were then histologically proven. PET-CT showed distant lesions in three patients. It had treatment-related implications in 23/38 patients (60%), consisting of modification of radiation planning, surgery or abstention from surgery. CONCLUSION: Hybrid FDG-PET-CT is helpful for the detection of a potential head and neck primary tumour. Furthermore, hybrid FDG-PET-CT has the ability to diagnose occult or distant second tumour and metastatic disease and modify patient management.     

18F-FDG-PET-CT imaging findings of recurrent intracranial haemangiopericytoma with distant metastases

A 42-year-old woman presented with local recurrence and distant lung and liver metastases 7 years after resection of a primary intracranial haemangiopericytoma. Whole-body ¹⁸F-fluoro-2-deoxy-d-glucose (FDG)-positron emission tomography (PET)-CT scan showed no increased uptake in local recurrence or distant metastases except for a focus of increased FDG uptake within a hepatic metastasis. The hypermetabolic area correlated with an intratumoral hypoenhancing area on the CT scan. PET-CT scan may be useful to allow further understanding of the tumour.Haemangiopericytoma is an uncommon tumour and accounts for less than 1% of all intracranial tumours. It caused much confusion because of its imaging similarities to meningioma and its uncertain cellular origin. Its rarity, non-specific imaging findings and lack of specific tumour markers pose diagnostic difficulties.We report a case of intracranial haemangiopericytoma treated with surgical resection. Local recurrence and distant metastases in the lung and liver occurred seven years after complete resection of the primary intracranial tumour. ¹⁸F-fluoro-2-deoxy-d-glucose (FDG)-positron emission tomography–computed tomography (PET-CT) was performed for assessment of the extent of disease.     

Multiple muscle metastases from lung cancer detected by FDG PET/CT

A 71-year-old man with right lung mass, who was recently diagnosed histopathologically with pulmonary adenocarcinoma, was referred for staging of the primary tumor. Whole-body F-18 fluorodeoxyglucose positron emission tomography and computed tomography (FDG PET/CT) demonstrated multiple hypermetabolic foci in various skeletal muscle localizations, suggesting extensive metastatic muscle involvements in addition to increased FDG uptake in the primary tumor. Subsequent biopsy and histopathological study confirmed muscle metastasis from lung adenocarcinoma. Skeletal muscle metastasis from lung cancer is rare, but multiple muscle metastases are even more unusual. FDG PET/CT is able to detect unexpected metastatic involvements such as multiple muscle metastases in lung cancer patients.     

Feasibility of somatostatin receptor scintigraphy in the detection of occult primary gastro-entero-pancreatic (GEP) neuroendocrine tumours

The aim of this study was to assess the feasibility of somatostatin receptor scintigraphy (SRS) for the detection of the site of unknown primary neuroendocrine neoplasms in patients in whom clinical examination and conventional radiological imaging had failed to do so. From 1996 to 2000, 36 patients were referred with gastro-entero-pancreatic (GEP) neuroendocrine tumours. In these patients, no clinical, radiological or endoscopic diagnostic modalities had been able to identify the primary tumour. Twenty-nine patients had liver metastases. Of the others, one had skin and one had lymph node metastases, three had diffuse metastatic involvement and two had carcinoid syndrome. SRS was carried out with both whole-body and single-photon emission tomography (SPET) acquisition, 24 and 48 h after the intravenous administration of In-pentetreotide. SRS findings were suggestive of the possible site of the primary lesion in 14 patients (39%). Six patients underwent surgery on the basis of the SRS findings and, therefore, the final, i.e. pathological, diagnosis was reached. In two patients, the final diagnosis was obtained within 6 months of SRS by means of a follow-up computed tomography (CT) scan. In the remaining six patients, the final diagnosis was reached after at least 2 years of follow-up by means of clinical, radiological and/or nuclear medicine findings. In all eight patients, the primary site identified during follow-up was consistent with the SRS findings. It can be concluded that SRS modified management in the six patients who had surgery. However, the most important finding was that SRS prompted surgical management in 17% of cases.     

Metastatic disease of the brain: extra-axial metastases (skull, dura, leptomeningeal) and tumour spread

Extra-axial intracranial metastases may arise through several situations. Hematogenous spread to the meninges is the most frequent cause. Direct extension from contiguous extra-cranial neoplasms, secondary invasion of the meninges by calvarium and skull base metastases, and migration along perineural or perivascular structures are less common. Leptomeningeal invasion gives rise to tumour cell dissemination by the cerebrospinal fluid (CSF), eventually leading to neoplastic coating of brain surfaces. Contrast-enhanced magnetic resonance (MR) imaging is complementary to CSF examinations and can be invaluable, detecting up to 50% of false-negative lumbar punctures. MR findings range from diffuse linear leptomeningeal enhancement to multiple enhancing extra-axial nodules, obstructive communicating and non-communicating hydrocephalus. Both calvarial and epidural metastases infrequently transgress the dura, which acts as a barrier against tumour spread. Radionuclide bone studies are still a valuable screening test to detect bone metastases. With computed tomography (CT) and MR, bone metastases extending intracranially and primary dural metastases show the characteristic biconvex shape, usually associated with brain displacement away from the inner table. Although CT is better in detecting skull base erosion, MR is more sensitive and provides more detailed information about dural involvement. Perineural and perivascular spread from head and neck neoplasms require thin-section contrast-enhanced MR.     

Whole-body FDG-PET in patients with stage I non-seminomatous germ cell tumours

Relapse occurs in 30% of patients with stage I non-seminomatous germ cell tumours (NSGCT) within 1 year after orchiectomy. Whole-body positron emission tomography with fluorine-18 fluorodeoxyglucose (FDG-PET) may detect small metastases when standard staging with computed tomography (CT) and tumour markers is negative. In this study, 46 patients underwent FDG-PET after staging with normal CT and tumour markers. To exclude diagnostic test bias and workup bias, all patients had routine follow-up with repeated CT and tumour marker evaluation, even though the initial FDG-PET was positive. Thirty-six patients have remained disease free with a median follow-up of 48 months (range 24-76). Ten patients (22%) suffered disease relapse after a median of 2 months (range 1-8), and of these, seven had a true positive initial PET with increased uptake of FDG indicating metastatic disease. There were three false negative and no false positive PET scans. The sensitivity, specificity and accuracy of PET were 70%, 100% and 93%, respectively. The sensitivity of detecting small retroperitoneal metastases was 88%. The negative and positive predictive values were 92% and 100%, respectively, whereas the negative predictive value of standard staging procedures was 78%. FDG-PET thus seems to be superior to conventional staging (P=0.06) in stage I NSGCT. This non-invasive method may improve the overall management of patients with NSGCT.     

Skeletal muscle metastases: a three-part study of a not-so-rare entity

Objective

Our purposes were to explore the epidemiology of metastases to skeletal muscle and their detection on fused positron emission tomography and computed tomography.

Materials and methods

We evaluated the epidemiology of skeletal muscle metastases in the literature and among cases from our hospital and studied the prevalence and appearance of skeletal muscle metastases among 433 patients undergoing fused positron emission tomography and computed tomography for non-small-cell lung cancer.

Results

We found 264 cases of skeletal muscle metastases in 151 articles. Mean age was 57.8?years with 67% men. At our hospital we studied 70 cases. Mean patient age was 55.7?years with 63% men. The most common source was lung cancer, and the most common site of involvement was the muscles of the trunk. Among our lung cancer patients undergoing fused positron emission tomography and computed tomography, we found 7 (1.6%) with skeletal muscle metastases. In only one of these seven patients was the metastasis first discovered by another imaging modality. In one patient discovery of the metastasis at fused positron emission tomography and computed tomography changed management.

Conclusion

Skeletal muscle metastases are not rare. They may be more apparent at fused positron emission tomography and computed tomography than at other staging examinations, particularly contrast-enhanced CT scanning. Radiologists need to be alert to their presence when interpreting staging examinations in cancer patients.     

Imaging thrombus in cancer patients with FDG PET–CT

The incidence of thrombosis in patients with underlying primary malignancy is high. The thrombus may be the more common venous thromboembolism (VTE) or the rare tumour thrombus. VTE is a common entity in cancer patients and is managed with anticoagulant therapy, while tumour thrombosis requires aggressive multimodality management. Conventional imaging modalities, including ultrasonography, venography, contrast-enhanced computed tomography, and magnetic resonance imaging, are used routinely in such cases. With its increasing use in oncology, more and more such thrombi are encountered on 18F-fluorodeoxyglucose (FDG) positron emission tomography–computed tomography (PET–CT). Accurate characterisation of these lesions is of utmost importance owing to complementary functional information which it provides. FDG PET–CT has been found to be helpful in this context. This pictorial review discusses and illustrates the imaging features of thrombosis on FDG PET–CT.     

Value of radioimmunoscintigraphy with technetium-99m labelled anti-CEA monoclonal antibody (BW431/26) in the detection of colorectal cancer

This study was undertaken as part of a Coordinated Research Programme initiated by the International Atomic Energy Agency to evaluate the usefulness of radioimmunoscintigraphy (RIS) in the management of patients with colorectal cancer. Technetium-99m labelled BW431/26, a monoclonal antibody against carcino-embryonic antigen (CEA), was used. The study included 73 patients (31 females and 42 males). Sixty-eight patients were suspected of having recurrent colorectal adenocarcinoma while another five were suspected to have primary colorectal cancer. Images were acquired at 10 min and 4 and 24 h following the injection of radioantibody. The efficacy of RIS in tumour detection was evaluated by the findings at surgery, histological investigation and/or other diagnostic modalities and clinical follow-up. Four of five patients with suspected primary colorectal cancer gave true-positive results (three at primary sites, one at the site of a metastatic lesion) while one was false-positive. The overall accuracy of RIS in the diagnosis of recurrent colorectal cancer was 87%. Its sensitivity in the detection of locoregional or abdominal recurrence and liver metastases was 97% and 89% respectively. RIS was more accurate than computed tomography (CT) scan in the detection of pelvic recurrence and liver metastases while CT scan was far superior to RIS in detecting lung metastases. RIS proved most useful in patents who had rising CEA levels on clinical follow-up but in whom other work-up, including CT scan, was negative. The advantages of RIS include the ability to detect tumour recurrence prior to other investigations and to identify tumour recurrence in areas such as the pelvis, where CT and magnetic resonance imaging have their greatest weaknesses in diagnosing recurrent disease. The imaging accuracy is significantly increased when combined CT and antibody imaging is performed.     

Carcinoid tumours: predicting the location of the primary neoplasm based on the sites of metastases

Objectives

To predict the primary neuroendocrine tumour of the gastrointestinal tract site based on observed metastatic sites.

Methods

We studied data from the radiology database of a single, large cancer centre on 250 patients with pathologically confirmed neuroendocrine tumours. Primary tumour sites and the locations of metastases were collected from pathologic and radiologic reports of all available imaging modalities, such as computed tomography (CT), positron emission tomography (PET/CT), magnetic resonance imaging (MRI) and octreotide scans in the database. A nominal regression model was used to predict primary tumour site using the observed metastatic sites. Regression coefficients that were not statistically significant at the 5 % level were eliminated from the model in a stepwise procedure.

Results

Lung and liver metastases were not statistically significant predictors of the location of primary tumours (p?=?0.86 and 0.074, respectively); whereas, lymph node, bone, and peritoneal metastases were significant predictors (p?<?0.0001, 0.0004, and 0.014, respectively).

Conclusions

Metastatic neuroendocrine tumours to the lymph nodes, bone, and peritoneum can be used to predict the primary neuroendocrine site; however, metastases in the lung and liver alone cannot predict the site of the primary tumour site.

Key Points

? Imaging helps one to diagnose the location of primary neuroendocrine neoplasm and the associated metastases. ? Diffuse metastatic disease often makes identification of the primary difficult. ? A prediction model developed may help identification of the primary in this setting. ? It may also help identify occult metastases and thereby assist in management.     

Brain metastases with exceptional features from papillary thyroid carcinoma: report of three cases

We present three papillary thyroid carcinoma PTC patients with brain metastases who are unusual in many aspects. The first case is a unique 3mm papillary thyroid microcarcinoma (PTMC) patient with metastases to the cerebrum and lung. The solitary cerebral lesion was identified by iodine-131 whole- body scan ((131)I-WBS) and (131)I single photon emission tomography/computed tomography (SPET/CT). Almost complete response achieved after radiosurgery. The second case is a unique PTC patient with coexistent (131)I-negative cerebrum, adrenal gland and ilium metastases, which were identified by (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) and magnetic resonance imaging (MRI). Partial response achieved after radiosurgery. The third case is a patient with an incident solitary cystic cerebellar mass as a primary presentation of follicular variant of PTC and absent other distant metastases. In conclusion, widespread metastases from small PTMC may occur. Concomitant brain and adrenal metastases may occur in a same PTC patient. Brain metastasis may present as a cystic lesion.