Prospective comparison of 18F-FDG PET with conventional imaging modalities (CT, MRI, US) in lymph node staging of head and neck cancer

The aims of this study were to investigate the detection of cervical lymph node metastases of head and neck cancer by positron emission tomographic (PET) imaging with fluorine-18 fluorodeoxyglucose (FDG) and to perform a prospective comparison with computed tomography (CT), magnetic resonance imaging (MRI), sonographic and histopathological findings. Sixty patients with histologically proven squamous cell carcinoma were studied by PET imaging before surgery. Preoperative endoscopy (including biopsy), CT, MRI and sonography of the cervical region were performed in all patients within 2 weeks preceding 18F-FDG whole-body PET. FDG PET images were analysed visually and quantitatively for objective assessment of regional tracer uptake. Histopathology of the resected neck specimens revealed a total of 1284 lymph nodes, 117 of which showed metastatic involvement. Based on histopathological findings, FDG PET correctly identified lymph node metastases with a sensitivity of 90% and a specificity of 94% (P<10(-6)). CT and MRI visualized histologically proven lymph node metastases with a sensitivity of 82% (specificity 85%) and 80% (specificity 79%), respectively (P<10(-6)). Sonography revealed a sensitivity of 72% (P<10(-6)). The comparison of 18F-FDG PET with conventional imaging modalities demonstrated statistically significant correlations (PET vs CT, P = 0.017; PET vs MRI, P = 0.012; PET vs sonography, P = 0.0001). Quantitative analysis of FDG uptake in lymph node metastases using body weight-based standardized uptake values (SUVBW) showed no significant correlation between FDG uptake (3.7+/-2.0) and histological grading of tumour-involved lymph nodes (P = 0.9). Interestingly, benign lymph nodes had increased FDG uptake as a result of inflammatory reactions (SUVBW-range: 2-15.8). This prospective, histopathologically controlled study confirms FDG PET as the procedure with the highest sensitivity and specificity for detecting lymph node metastases of head and neck cancer and has become a routine method in our University Medical Center. Furthermore, the optimal diagnostic modality may be a fusion image showing the increased metabolism of the tumour and the anatomical localization.     

Identification of a novel antigenic structure of the human receptor for interleukin-6 involved in the interaction with the glycoprotein 130 chain

PURPOSE: To evaluate the diagnostic accuracy of positron emission tomography (PET) with administration of 2-deoxy-2-[fluorine-18]fluoro-D-glucose (FDG) relative to that of magnetic resonance (MR) imaging and/or computed tomography (CT) in recurrent head and neck cancers. MATERIALS AND METHODS: Twelve adult patients (mean age, 63 years) with previously treated head and neck cancers and clinical suspicion of recurrence underwent FDG PET and MR imaging and/or CT. All images were blindly and independently interpreted without histopathologic findings (obtained within 1 week of imaging). The level of confidence in image interpretation was graded by using a five-point rating system (0 = definitely no recurrence to 4 = definite recurrence). RESULTS: Recurrence was confirmed in eight patients. With a rating of 4 as a positive finding, FDG PET yielded a sensitivity and specificity of 88% (seven of eight) and 100% (four of four), respectively; MR imaging and/or CT, 25% (two of eight) and 75% (three of four), respectively. Receiver-operating characteristic analysis showed significantly better diagnostic accuracy with FDG PET than with MR imaging and/or CT (area under curve = 0.96 vs 0.55, P < .03). CONCLUSION: These data indicate that PET metabolic imaging, as compared with anatomic methods, has improved diagnostic accuracy for recurrent head and neck cancer.     

Computed tomography and positron emission tomography in the pre-operative staging of oesophageal carcinoma

Because patients with carcinoma of the oesophagus usually present with advanced disease and surgery has a high mortality with cure in less than 10% of patients, pre-operative staging to select appropriate patients is necessary. Computed tomography (CT) plays an important role in staging but has well recognized limitations. Positron emission tomography (PET) which provides physiological information may therefore be a better alternative. OBJECTIVE: To compare the findings of CT and positron emission tomography (PET) with 2-[18fluorine]-fluoro-2-deoxy-D-glucose (FDG) in the pre-operative staging of oesophageal carcinoma. MATERIALS AND METHODS: Twenty-five patients with biopsy proven oesophageal cancer had pre-operative staging using CT and FDG-PET. The studies were read independently and full histological confirmation was obtained in 19 patients. Four parameters were studied: the primary tumour, peri-oesophageal lymph nodes, liver metastases and left gastric lymph nodes. RESULTS: PET visualized all primary tumours; CT missed one. CT identified 4/8 patients with involved peri-oesophageal nodes and PET 3/8. CT identified 5/9 patients with left gastric adenopathy and PET 1/9. PET visualized a liver metastasis missed on CT and appeared to be better in assessing residual tumour. PET did identify distant metastases not seen on CT in seven patients. CONCLUSIONS: The two techniques are both effective in showing the primary tumour and about equally sensitive in the demonstration of peri-oesophageal nodes. PET is probably more sensitive than CT for the detection of distant metastases.     

Applications of PET in lung cancer

An estimated 180,000 new cases of lung cancer will be diagnosed in the United States this year, and lung cancer accounts for approximately 25% of all cancer deaths. The overall 5-year survival rate is 14%, and this has not changed over the past several decades. Lung cancer diagnosis and treatment is a major health problem globally. Most lung cancers are detected initially on chest radiographs, but many benign lesions have radiologic characteristics similar to malignant lesions. Thus, additional studies are required for further evaluation. Computed tomography (CT) is most frequently used to provide additional anatomic and morphologic information about the lesion, but it is limited in distinguishing benign from malignant abnormalities in the lung, pleura, and mediastinum. Because of the indeterminate results from anatomic imaging, biopsy procedures including thoracoscopy and thoracotomy may be used even through one-half of the lesions removed are benign and do not need to be removed. FDG-PET imaging provides physiologic and metabolic information that characterizes lesions that are indeterminate by CT and that accurately stages the distribution of lung cancer. Exploiting the fundamental biochemical differences between cancer and normal tissues, FDG imaging takes advantage of the increased accumulation of FDG in transformed cells. FDG-PET is very sensitive (approximately 95%) for the detection of cancer in patients who have indeterminate lesions on CT. The specificity (approximately 85%) of PET imaging is slightly less than the sensitivity because some inflammatory processes such as active granulomatous infections accumulate FDG avidly. The high-negative predictive value of PET suggests that lesions considered negative on the study are benign, biopsy is not needed, and radiographic follow-up is recommended. Several studies have documented the increased accuracy of PET compared with CT in the evaluation of the hilar and mediastinal lymph node status in patients with lung cancer. If the mediastinum is normal on PET imaging and there is no other evidence of metastatic disease, the patient has a thoracotomy. If the mediastinum is abnormal on PET imaging, mediastinoscopy is performed with the PET images providing the lymph node stations to target. Whole-body PET studies detect metastatic disease that is unsuspected by conventional imaging and demonstrate some of the anatomic abnormalities detected by CT to be benign lesions. Management changes have been reported to occur in up to 41% of patients based on the results of the whole-body studies.     

FDG PET of the retroperitoneum: normal anatomy, variants, pathologic conditions, and strategies to avoid diagnostic pitfalls

Evaluation of the retroperitoneum is important to assess the extent of retroperitoneal malignancies and because the retroperitoneum is a route of nodal spread for other malignancies. Positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) allows detection of small malignant nodes not identified or not meeting size criteria for malignancy with computed tomography (CT) and tumor recurrences in surgical beds that are otherwise difficult to assess. However, evaluation of retroperitoneal malignancies or adenopathy with FDG PET can be complicated by urinary and colonic activity or anatomic variants. Urinary artifacts are avoided with intravenous hydration, administration of furosemide, and catheterization and retrograde filling of the bladder with saline solution. Colonic artifacts are avoided by cleansing the bowel with an isosmotic solution. FDG PET is useful in assessing the retroperitoneum for adenopathy in malignancies such as testicular cancer; lymphoma; and rectal ovarian, or cervical cancer that spread along retroperitoneal lymphatics. FDG PET is especially useful for detection of malignant nodes that do not meet size criteria at CT or when lack of retroperitoneal fat makes it difficult to identify retroperitoneal nodes with CT. FDG PET has an important role in evaluation of postoperative beds, where CT has limited useful because of altered anatomy, surgical clip artifacts, and scar issue.     

Pitfalls in oncologic diagnosis with FDG PET imaging: physiologic and benign variants

A rapidly emerging clinical application of positron emission tomography (PET) is the detection and staging of cancer with the glucose analogue tracer 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG). Proper interpretation of FDG PET images requires knowledge of the normal physiologic distribution of the tracer, frequently encountered physiologic variants, and benign pathologic causes of FDG uptake that can be confused with a malignant neoplasm. One hour after intravenous administration, high FDG activity is present in the brain, the myocardium, and--due to the excretory route--the urinary tract. Elsewhere, tracer activity is typically low, a fact that allows sensitive demonstration of tracer accumulation in many malignant neoplasms. Interpretive pitfalls commonly encountered on FDG PET images of the body obtained 1 hour after tracer administration can be mistaken for cancer. Such pitfalls include variable physiologic FDG uptake in the digestive tract, thyroid gland, skeletal muscle, myocardium, bone marrow, and genitourinary tract and benign pathologic FDG uptake in healing bone, lymph nodes, joints, sites of infection, and cases of regional response to infection and aseptic inflammatory response. In many instances, these physiologic variants and benign pathologic causes of FDG uptake can be specifically recognized and properly categorized; in other instances, such as the lymph node response to inflammation or infection, focal FDG uptake is nonspecific.     

Detection of extrathoracic metastases by positron emission tomography in lung cancer

BACKGROUND: Accurate staging of non-small cell lung cancer is essential for treatment planning. We evaluated in a prospective study the role of whole-body 2-[18F]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) in mediastinal nodal staging with a positive predictive value of 96%. The study was continued to further evaluate the value of whole-body FDG PET in detecting unexpected extrathoracic metastases (ETMs) in patients qualifying for surgical treatment by conventional staging. METHODS: One hundred patients underwent clinical evaluation, chest and upper abdominal computed tomography scan, mediastinoscopy (lymph nodes greater than 1 cm on computed tomography), and routine laboratory tests. In 94 patients with stage IIIa or less and 6 with suspected N3 a whole-body FDG PET was performed. If clinical signs of ETMs were present additional diagnostic methods were applied. All findings in the FDG PET were confirmed histologically or radiologically. RESULTS: Unexpected ETMs were detected in 13 (14%) of 94 patients (stage IIIa or less) at 14 sites. In addition 6 of 94 patients were restaged up to N3 after PET. The suspected N3 disease (stage IIIb) on computed tomography was confirmed by PET in all 6 patients. There was no false positive finding of ETM. Weight loss was correlated with the occurrence of ETM: more than 5 kg, 5 of 13 patients (38%); more than 10 kg, 4 of 6 patients (67%). Pathologic laboratory findings were not predictive for ETM. CONCLUSIONS: Whole-body FDG PET improves detection of ETMs in patients with non-small cell lung cancer otherwise elegible for operation. In 14% of patients (stage IIIa or less), ETMs were detected, and in total, 20% of the patients were understaged.     

FDG PET in head and neck cancer

In our extensive experience with FDG PET imaging in head and neck cancer, we have found the technique to be of high accuracy but of limited usefulness. This seeming paradox arises from several causes. Competing techniques such as CT, MR imaging, and even clinical examination already have good accuracy. In addition, high-resolution studies such as CT and MR imaging provide information required for treatment planning that is unavailable from FDG PET images. The high cost of FDG PET militates against its use in this setting, in which only a small marginal gain can be expected. In the special problem areas in which FDG PET might be expected to offer unique advantages, such as screening for second primary lesions, searching for unknown primary lesions, or differentiating benign salivary rumors from malignant lesions, the results of FDG PET have been disappointedly poor. Of these special problem areas, only the question of accuracy in finding occult primary lesions appears unresolved and in need of further study. The single application in which FDG PET appears to be advantageous is the posttherapy setting. In this setting, the technique is definitely superior to alternative methods of determining tumor recurrence and differentiating posttherapy sequelae such as radiation necrosis from tumor recurrence. We believe that considerable opportunity remains for further research on the use of FDG PET in head and neck cancer. Other agents such as 11C-methionine for example, might improve the diagnostic accuracy of FDG PET in some of the problem areas that we have identified, such as the early postirradiation period. We currently have such a study under way. Also, because FDG PET offers a unique way to measure tumor metabolism, further investigation of the use of FDG PET tracers to evaluate various biologic parameters such as proliferation rates or tumor hypoxia are needed. Such studies could provide a noninvasive technique to identify which fractionation schemes or combinations of therapy might be useful for individual patients. A final caveat is in order. Although our findings of the usefulness (and lack thereof) of FDG PET in head and neck cancer may be disappointing to many, these results should not be generalized to other applications of FDG PET in oncology. Each tumor type and setting presents its own specific problems, and in some instances FDG PET offers unique advantages over other imaging techniques. A good example is the setting of primary lung cancer, in which FDG PET appears clearly superior to all other methods of pretherapy screening [19-20].     

Assessment of axillary lymph node involvement in breast cancer patients with positron emission tomography using radiolabeled 2-(fluorine-18)-fluoro-2-deoxy-D-glucose

BACKGROUND: The presence of metastatic tumor cells in the axillary lymph nodes is an important factor when deciding whether or not to treat breast cancer patients with adjuvant therapy. Positron emission tomography (PET) imaging with the radiolabeled glucose analogue 2-(fluorine-18)-fluoro-2-deoxy-D-glucose (F-18 FDG) has been used to visualize primary breast tumors as well as bone and soft-tissue metastases. PURPOSE: This study was undertaken to evaluate before surgery the diagnostic accuracy of PET for detection of axillary lymph node metastases in patients suspected of having breast cancer. METHODS: Women who were scheduled to undergo surgery for newly discovered, suspected breast cancers were referred for PET imaging of the axilla region. The women were first clinically examined to determine the status of their axillary lymph nodes (i.e., presence or absence of metastases). Fifty-one women were intravenously administered F-18 FDG and were studied by PET imaging. Attenuation-corrected transaxial and coronal images were visually evaluated by two nuclear medicine physicians (blinded to the patient's medical history) for foci of increased F-18 FDG uptake in the axilla region. All patients underwent surgery for their suspected breast cancers. Axillary lymph node dissection was also performed on all patients with breast cancer, with the exception of four patients who received primary chemotherapy for locally advanced breast cancer. A single pathologist analyzed breast tumor and lymph node tissue specimens. RESULTS: The overall sensitivity (i.e., the ability of the test to detect disease in patients who actually have disease) and specificity (i.e., the ability of the test to rule out disease in patients who do not have disease) of this method for detection of axillary lymph node metastases in these patients were 79% and 96%, respectively. When only patients with primary breast tumors larger than 2 cm in diameter (more advanced than stage pT1; n = 23) were considered, the sensitivity of axillary PET imaging increased to 94%, and the corresponding specificity was 100%. Lymph node metastases could not be identified in four of six patients with small primary breast cancers (stage pT1), resulting in a sensitivity of only 33%. Axillary PET imaging provided additional diagnostic information in 12 (29%) of 41 breast cancer patients with regard to the extension of disease to other sites (i.e., other lymph nodes, skin, bone, and lung). CONCLUSIONS: PET imaging with F-18 FDG allowed accurate and noninvasive detection of axillary lymph node metastases, primarily in patients with breast cancer more advanced than stage pT1. Detection of micrometastases and small tumor-infiltrated lymph nodes is limited by the currently achievable spatial resolution of PET imaging. IMPLICATIONS: In clinical practice, PET imaging cannot substitute for histopathologic analysis in detecting axillary lymph node metastases in breast cancer patients. PET imaging, however, improves the preoperative staging of the disease in breast cancer patients and, therefore, might alter therapeutic regimen options.     

Lymphoma: role of whole-body 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) PET in nodal staging

PURPOSE: To compare 2-deoxy-2-[fluorine-18]fluoro-D-glucose (FDG) positron emission tomography (PET) with computed tomography (CT) in primary nodal staging of malignant lymphoma. MATERIALS AND METHODS: Sixty consecutive patients with untreated, histopathologically proved malignant lymphoma (aged 7-72 years; 33 with non-Hodgkin lymphoma, 27 with Hodgkin disease) underwent FDG PET and contrast material-enhanced CT for nodal staging. Lymph node regions identified at both CT and PET were regarded as actual locations of disease. Discordant results were verified with biopsy or clinical follow-up whenever possible. RESULTS: One hundred sixty of 740 evaluated lymph node regions were identified as diseased at both CT and PET. Of the 25 additional regions seen with PET, seven were true-positive; two, false-positive; and 16, unresolved. CT showed six additional disease manifestations; three were false-positive, and three were unresolved. Staging was changed in the four patients with the seven confirmed additional PET findings: from stage I to II in one patient and from stage II to III in three patients. Staging was changed from stage II to I in one of the three patients with false-positive CT findings. CONCLUSION: FDG PET may be more accurate for detecting nodal lymphoma than incremental CT.     

Comparison of imaging TNM [(i)TNM] and pathological TNM [pTNM] in staging of bronchogenic carcinoma

OBJECTIVE: Precise tumor (T) and nodal (N) staging is imperative in non-small cell lung cancer (NSCLC) as it determines subsequent treatment, certainly when considering neoadjuvant treatment for stage IIIA or IIIB disease. To determine the accuracy of present-day computed tomographic (CT) scanning a prospective study was performed comparing imaging TNM [(i)TNM] and pathological TNM [pTNM]. METHODS: In 74 patients with NSCLC without distant metastases (i)TNM was determined on CT findings. The TNM system advocated by the American Joint Committee on Cancer was used. All patients underwent cervical mediastinoscopy. When superior mediastinal nodes were negative this was followed by thoracotomy and pathological examination of the resected specimen and lymph nodes to determine pTNM. RESULTS: The agreement between (i)TNM and pTNM was only 35.1%. The primary tumor (T) was correctly staged in 54.1%, overstaged in 27.0% and understaged in 18.9% of the patients. Invasion of chest wall, pericardium and of major mediastinal structures (T3, T4) was not reliably detected by CT scan. Sensitivity and specificity of CT regarding hilar and mediastinal lymph node staging were 48.3 and 53.3%, positive and negative predictive value 40 and 61.1% and its overall accuracy 51.4%. The nodal (N) factor was correctly determined by CT scan in 35.1%, overstaged in 44.6%, and understaged in 20.3% of the patients. CONCLUSIONS: Even with present-day CT scanners (i)TNM provides no accurate staging and routine mediastinoscopy is necessary for precise mediastinal lymph node staging. Likewise, (i)T3 and (i)T4 determinations are unreliable and should not contraindicate thoracotomy.     

Imaging of abdominal manifestations of melanoma

Despite an increasing incidence of melanoma in this country, innovative new therapies are allowing patients to receive aggressive experimental treatments. Diagnostic imaging remains crucial for tumor staging and for follow-up of patients being treated with these protocols. Because metastases occur in the abdomen and pelvis in approximately 60% of patients, it is important to accurately identify all sites of tumor spread. A variety of imaging techniques are used to image these patients, with CT currently being used for staging purposes and to guide diagnostic biopsies. Other imaging techniques, such as MR, ultrasound, and fluoroscopy, are currently reserved for investigating specific complications of melanoma, such as vascular invasion, hemorrhage from a tumor, and small bowel involvement, including intussusception. Recently, whole body positron emission tomography (PET) imaging using 2-deoxy-2-fluoro-D-glucose (FDG) has been shown to be highly accurate in assessing patients with metastatic malignant melanoma. This review illustrates the spectrum of manifestations of metastatic melanoma throughout the abdomen and pelvis, including solid organ, hollow lumen, and retroperitoneal involvement, and demonstrates some of the typical and atypical manifestations that may be identified.     

Improved retroperitoneal and gastrointestinal sonography using oral contrast agents in a porcine model

PURPOSE: To evaluate use of functional imaging with positron emission tomography (PET) versus computed tomography (CT) for detection of extranodal lymphoma spread. MATERIALS AND METHODS: Eighty-one consecutive and previously untreated patients with malignant non-Hodgkin lymphoma (n = 43) or Hodgkin disease (n = 38) were examined with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) PET and contrast material-enhanced CT. Concordant findings at both CT and FDG PET were regarded as actual locations of disease; discordant results were resolved on the basis of biopsy or follow-up results when possible. RESULTS: Forty-two lesions were identified at both PET and CT, and 19 were verified with biopsy results. PET demonstrated a further 24 lesions. Verification was possible in 15 of these lesions with biopsy (n = 10), magnetic resonance imaging (n = 1), scintigraphic (n = 1), or follow-up (n = 3) results. In 14 of these 15 lesions, PET findings were confirmed (bone marrow, nine; spleen, three; other, two). Seven lesions not visualized at FDG PET were identified at CT, six of which were verified with biopsy (n = 2) or follow-up (n = 4) results. Five of these six CT findings were found to be erroneous. In 13 patients, PET findings led to changes in tumor staging. CONCLUSION: PET may provide more information about extranodal lymphoma than does incremental CT.     

Acute therapy of episodic and chronic cluster headache with sumatriptan s.c. Results of a one-year long-term study

Breast cancer is the commonest malignancy to affect women. The malignant process may present clinicians with problems in establishing the diagnosis expeditiously, accurately staging the disease and assessing tumour response to primary systemic chemotherapy. Considerable recent interest has focused on the application of imaging techniques that utilize tumour-specific gamma-ray-emitting radiopharmaceuticals to resolve these problems. The wide availability of gamma camera systems makes single photon-imaging techniques, using radiopharmaceuticals incorporating conventional isotopes, attractive options. However, results concerning the detection of the primary breast cancer and the staging of axillary lymph nodes suggest that these techniques would appear to offer no significant advantages, when compared with those obtained using standard diagnostic methods. Dual gamma-ray-emission imaging by positron emission tomography (PET) may offer an alternative solution. Studies performed show that PET can accurately detect primary breast cancers, stage locoregional lymph nodes and visualize distant tumour metastases. Furthermore, PET may be able to monitor early tumour response to chemotherapy agents. It would appear, therefore, that dual gamma emission might have an important role to play in the management of patients with breast cancer.     

Evaluation of pancreatic tumors with positron emission tomography and F-18 fluorodeoxyglucose: comparison with CT and US

PURPOSE: To assess the clinical value of positron emission tomography (PET) with fluorine-18-labeled fluorodeoxyglucose (FDG) for identification of pancreatic carcinoma. MATERIALS AND METHODS: Forty-six patients suspected of having a pancreatic neoplasm and who were to undergo surgery prospectively underwent FDG PET, computed tomography (CT), and transabdominal ultrasound (US). Endoscopic US was performed in 40 patients. Images were independently interpreted and compared with the histopathologic findings at surgery (41 patients) or with clinical follow-up findings (five patients). RESULTS: In 33 of 35 patients, foci of pancreatic carcinomas (10-100 mm in diameter) were identified as an increase in FDG uptake, whereas CT, transabdominal US, and endoscopic US depicted the foci in 31, 31, and 28, cases, respectively. Among 11 benign lesions, nine showed no increased FDG uptake (specificity = 82%). Specificities of the other modalities were lower. False-positive findings were obtained in a case of chronic active pancreatitis and in a serous cystadenoma. CONCLUSION: FDG PET, which provides "biochemical" information, is accurate in identifying pancreatic carcinoma and may be a method of choice when imaging equivocal masses detected with other "anatomic" imaging studies.     

Whole-body [18F]FDG PET in the management of metastatic brain tumours

BACKGROUND: To determine its roles in the diagnosis and the systemic evaluation of metastatic brain tumours, whole-body positron emission tomography (PET) using [18F]FDG was performed in 20 consecutive patients. METHODS: All patients were thought to be suffering or needing to be differentiated from metastatic brain tumours. Nine patients had multiple brain lesions; six were older and showed a rim-enhancing lesion with surrounding oedema; seven had homogeneously enhancing periventricular lesion(s) on computed tomography (CT) and/or magnetic resonance (MR) imaging, thought to be central nervous system lymphomas. Two patients had skull mass(es) and two patients had a solid mass suspected to be, respectively, a haemorrhagic metastasis and a metastatic malignant melanoma. All of them received whole-body [18F]FDG PET and conventional systemic work-up for metastasis in order to compare the results of the two methods. RESULTS: Metastatic brain tumours were diagnosed on whole-body [18F]FDG PET in eleven patients who had extracranial and intracranial hypermetabolic lesions. In nine of these, a conventional work-up also detected primary lesions which on whole-body [18F]FDG PET were seen to be hypermetabolic foci. Systemic lymph node metastases were detected by whole-body [18F]FDG PET only in two patients and histological diagnosis was possible by biopsy of lymph nodes rather than of brain lesions. In the remaining nine patients who had only intracranial hypermetabolic foci, histological diagnosis was made by craniotomy or stereotactic biopsy. It was confirmed that seven of nine patients were suffering from a primary brain tumour and two from metastatic carcinoma. None of the nine showed evidence of systemic cancer on conventional work-up. Histological diagnoses of the primary brain tumours were four cases of primary central nervous system lymphoma and one each of multifocal glioblastoma, Ewing's sarcoma, and cavernous angioma. Patients felt no discomfort during the whole-body [18F]FDG PET procedure and there were no complications. The false negative rate in [18F]FDG PET and in conventional work-up was 15.4% and 30.7% respectively. There were no false positives on either [18F]FDG PET or conventional work-up. CONCLUSION: It is suggested that whole-body [18F]FDG PET is a safe, reliable, and convenient method for the diagnosis and systemic evaluation of patients thought to be suffering or needing to be differentiated from a metastatic brain tumour.     

Primary muscle lymphoma: clinical and imaging findings

PURPOSE: To assess the clinical and imaging findings in primary muscle lymphoma. MATERIALS AND METHODS: Seven patients with biopsy-proved primary muscle lymphoma without evidence of systemic disease underwent imaging with plain radiography or computed tomography (CT) and magnetic resonance (MR) imaging. Four underwent bone scintigraphy, and two underwent gallium scintigraphy and fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) before and after therapy. RESULTS: Plain radiographs at initial examination (n = 5) showed no bone abnormalities. Soft-tissue masses and bone marrow involvement showed isoattenuation at CT (n = 3), but at MR imaging (n = 7), all masses demonstrated increased signal intensity on T2-weighted images that involved multiple muscle compartments and typically spanned a long segment of the extremity. Adjacent bone disease was less extensive than muscle disease, and, in most cases, subcutaneous stranding or extension was observed adjacent to the masses. Good size correlation was observed between findings at MR imaging, gallium scintigraphy, and FDG PET. Two patients developed recurrent multifocal muscle lymphoma several years after initial examination. CONCLUSION: The presence of an extensive soft-tissue mass with infiltration of adjacent subcutaneous fat and minimal or no extension into the bone marrow cavity at MR imaging and normal plain radiographic findings may suggest primary muscle lymphoma.     

Fluorine-18-fluorodeoxyglucose PET identification of cardiac metastasis arising from uterine cervical carcinoma

Cardiac metastasis of uterine cervical carcinoma is rare. We describe a patient with a past history of uterine cervical carcinoma who presented with metastasis to the heart, lungs and distant lymph nodes 3 yr after surgery and chemotherapy. Since the patient complained of chest pain and demonstrated electrocardiogram abnormalities, we performed echocardiography, electron beam CT and MRI, which revealed a tumor in the right ventricular wall. The tumor was assessed by 67Ga scintigraphy and 18F-fluorodeoxyglucose (FDG) PET scanning. The mean differential 18F-FDG uptake ratio of the tumor was 7.9, suggesting malignancy, which was later confirmed by myocardial biopsy. Information about the extent of the tumor and partial necrosis within it was provided by 18F-FDG PET. Although both radionuclide imaging techniques also detected metastatic lesions in the lungs and lymph nodes, 18F-FDG PET scanning detected small lesions more sensitively than 67Ga scintigraphy.     

Pretherapeutic staging of laryngeal carcinoma. Clinical findings, computed tomography, and magnetic resonance imaging compared with histopathology

BACKGROUND: An accurate pretherapeutic staging of laryngeal carcinoma is required for most treatment planning as well as for evaluation and comparison of the results of different treatment modalities. Neoplastic invasion of the laryngeal cartilage may have important therapeutic implications. To our knowledge, no data are available comparing the impact of endoscopic examination, computed tomography (CT), and magnetic resonance (MR) imaging on pretherapeutic staging accuracy. The purpose of our study was to determine which imaging should be used as an adjunct to other clinical examinations in the pretherapeutic staging of laryngeal carcinoma. METHODS: In this study, 40 consecutive patients with neoplasms of the larynx, who were treated surgically, were included in a prospective pretherapeutic staging protocol that included indirect laryngoscopy, direct microlaryngoscopy, contrast-enhanced CT, and gadolinium-diethylenetriamine pentaacetic acid-enhanced MR imaging at 1.5 Tesla. The surgical specimens were cut in whole-organ slices parallel to the plane of the axial CT and MR images. The histologic findings were compared with the clinical findings including the CT and MR images. The impact of each diagnostic method on pretherapeutic staging was analyzed. RESULTS: Clinical/endoscopic evaluation failed to correctly stage 17 tumors due to invasion of the paraglottic space (1 tumor), preepiglottic space (2 tumors), and extralaryngeal soft tissues (14 tumors), resulting in a pretherapeutic staging accuracy of 57.5%. Neoplastic invasion of cartilage was present in 28 patients and absent in 12 patients. Although MR imaging was more sensitive in detecting neoplastic invasion of cartilage than CT (94% vs. 67%; P = 0.001), MR imaging was less specific than CT (74% vs. 87%; P = 0.007). There was no difference between the overall accuracy of CT and MR imaging in detecting neoplastic invasion of cartilage (80% vs. 82%). The accuracy of combined clinical/endoscopic examination and CT staging was 80% and the accuracy of combined clinical/endoscopic examination and MR imaging staging was 87.5%; the difference was not statistically significant. CONCLUSIONS: Clinical/endoscopic examination alone failed to identify tumor invasion of the laryngeal cartilages and of the extralaryngeal soft tissues, resulting in a low staging accuracy (57.5%). Many pT4 (according to the International Union against Cancer TNM Staging System) tumors were clinically unrecognized. The combination of clinical/endoscopic evaluation and an additional radiologic examination, either CT or MR imaging, resulted in significantly improved staging accuracy (80% vs. 87.5%). MR imaging is significantly more sensitive but less specific than CT in detecting neoplastic cartilage invasion. Therefore, MR imaging tends to overestimate neoplastic cartilage invasion and may result in overtreatment, whereas CT tends to underestimate neoplastic cartilage invasion and may lead to inadequate therapy.     

Mediastinal lymph node metastasis from lung cancer: evaluation with Tl-201 SPECT--comparison with CT

PURPOSE: To assess the usefulness of thallium-201 single photon emission computed tomography (SPECT) in detection of mediastinal lymph node metastasis from lung cancer. MATERIALS AND METHODS: Computed tomography (CT) and Tl-201 SPECT were performed in 113 patients with lung cancer. Surgical staging was performed in all patients, and the results of the two modalities were compared with the pathologic findings in 364 node stations. RESULTS: Cancerous nodes were found in 32.7% of the patients. The sensitivity of CT in detecting mediastinal node metastasis was 62%; specificity was 80%. These rates were higher for Tl-201 SPECT (76% and 92%, respectively). Furthermore, these rates were excellent in patients with enlarged mediastinal nodes at CT (87% and 93%, respectively). However, Tl-201 SPECT had more limited spatial resolution than did CT. CONCLUSION: Tl-201 SPECT is useful in evaluation of mediastinal node metastasis in lung cancer, especially for patients with enlarged nodes at CT.