Intraparenchymal brain metastases: MR imaging versus contrast-enhanced CT

The Usefulness of Computer-Aided Detection of Brain Metastases on Contrast-Enhanced Computed Tomography Using Single-Shot Multibox Detector: Observer Performance Study

OBJECTIVE

This study aimed to test the usefulness of computer-aided detection (CAD) for the detection of brain metastasis (BM) on contrast-enhanced computed tomography.

METHODS

The test data set included whole-brain axial contrast-enhanced computed tomography images of 25 cases with 62 BMs and 5 cases without BM. Six radiologists from 3 institutions with 2 to 4 years of experience independently reviewed the cases, both in conditions with and without CAD assistance. Sensitivity, positive predictive value, number of false positives, and reading time were compared between the conditions using paired t tests. Subanalysis was also performed for groups of lesions divided according to size. A P value <0.05 was considered statistically significant.

RESULTS

With CAD, sensitivity significantly increased from 80.4% to 83.9% (P = 0.04), whereas positive predictive value significantly decreased from 88.7% to 84.8% (P = 0.03). Reading time with and without CAD was 112 and 107 seconds, respectively (P = 0.38), and the number of false positives was 10.5 with CAD and 7.0 without CAD (P = 0.053). Sensitivity significantly improved for 6- to 12-mm lesions, from 71.2% without CAD to 80.3% with CAD (P = 0.02). The sensitivity of the CAD (95.2%) was significantly higher than that of any reader (with CAD: P = 0.01; without CAD: P = 0.005).

CONCLUSIONS

Computer-aided detection significantly improved BM detection sensitivity without prolonging reading time while marginally increased the false positives.

Current approaches to the management of brain metastases

Brain metastases are a very common manifestation of cancer that have historically been approached as a single disease entity given the uniform association with poor clinical outcomes. Fortunately, our understanding of the biology and molecular underpinnings of brain metastases has greatly improved, resulting in more sophisticated prognostic models and multiple patient-related and disease-specific treatment paradigms. In addition, the therapeutic armamentarium has expanded from whole-brain radiotherapy and surgery to include stereotactic radiosurgery, targeted therapies and immunotherapies, which are often used sequentially or in combination. Advances in neuroimaging have provided additional opportunities to accurately screen for intracranial disease at initial cancer diagnosis, target intracranial lesions with precision during treatment and help differentiate the effects of treatment from disease progression by incorporating functional imaging. Given the numerous available treatment options for patients with brain metastases, a multidisciplinary approach is strongly recommended to personalize the treatment of each patient in an effort to improve the therapeutic ratio. Given the ongoing controversies regarding the optimal sequencing of the available and expanding treatment options for patients with brain metastases, enrolment in clinical trials is essential to advance our understanding of this complex and common disease. In this Review, we describe the key features of diagnosis, risk stratification and modern paradigms in the treatment and management of patients with brain metastases and provide speculation on future research directions.

Brain metastasis in lung cancer

FDG-PET/CT is increasingly used in staging of lung cancer as single „one stop shop” method. Aim, patients, methods: We prospectively included 104 neurological asymptomatic patients (65 years, 26% women) with primary diagnosis of lung cancer. In all patients PET/CT including cerebral imaging and cerebral MRI were performed. Results: Diagnosis of brain metastases (BM) was made by PET/CT in 8 patients only (7.7%), by MRI in 22 (21.2%). In 80 patients both PET/CT and MRI showed no BM. In 6 patients (5.8%) BM were detectable on PET/CT as well as on MRI. Exclusive diagnosis of BM by MRI with negative finding on PET/CT was present in 16 patients (15.4%). 2 patients (1.9%) had findings typical for BM on PET/CT but were negative on MRI. With MRI overall 100 BM were detected, with PET/CT only 17 BM (p < 0.01). For the diagnosis of BM PET/CT showed a sensitivity of 27.3%, specificity of 97.6%, positive predictive value of 75% and negative predictive value of 83.3%. BM diameter on PET/CT and MRI were consistent in 43%, in 57% BM were measured larger on MRI. Discussion: Compared to the gold standard of MRI for cerebral staging a considerable number of patients are falsely diagnosed as free from BM by PET/CT. MRI is more accurate than PET/CT for detecting multiple and smaller BM. Conclusion: In patients with a curative option MRI should be performed additionally to PET/CT for definitive exclusion of brain metastases.

Added value of diffusion weighted imaging in pediatric central nervous system embryonal tumors surveillance

Diffusion weighted imaging (DWI) has an established role in primary CNS embryonal tumor (ET) characterization; however, its diagnostic utility in detecting relapse has never been determined. We aimed to compare DWI and conventional MRI sensitivity in CNS ET recurrence detection, and to evaluate the DWI properties of contrast-enhancing radiation induced lesions (RIL). Fifty-six patients with CNS ET (25 with disease relapse, 6 with RIL and 25 with neither disease relapse nor RIL) were retrospectively evaluated with DWI, conventional MRI (including both T2/FLAIR and post-contrast images), or contrast-enhanced MR imaging (CE-MRI) alone. MRI studies were independently reviewed by two neuroradiologists for detection and localization of potential brain relapses. Sensitivity for focal relapse detection was calculated for each image set on a lesion-by-lesion basis. A descriptive per subject analysis was also performed. Evaluation of follow-up MRI studies served as standard of reference. Focal recurrence detection sensitivity of DWI (96%) was significantly higher than conventional MRI (77%) and CE-MRI alone (51%) (p=0.0003 and p<0.0001). On per subject analysis there were not missed diagnoses for DWI. At the time of DWI relapse detection, conventional MRI missed 2 diagnoses, and CE-MRI 8. Analysis of medulloblastoma relapses revealed that DWI identified a higher number of focal lesions than CE-MRI in subjects with classic variant. All but one RIL did not show restricted diffusion. In conclusion, DWI is a valuable complementary technique allowing for improved detection of focal relapse in CNS ET patients, particularly in children with classic medulloblastoma, and may assist in differentiating recurrence from RIL.

MIP Improves Detection of Brain Metastases

PURPOSE

This study aimed to compare the sensitivity for detection of brain metastases using postcontrast 3-dimensional, T1W-gradient echo sequence (3DT1W) and maximum intensity projections (MIPs) obtained from the same data set.

MATERIALS AND METHODS

A prospective analysis of patients with known brain metastases was performed. We compared 1-mm postcontrast 3DT1W with 6-mm MIP reconstructions obtained from the same images (MIP-3DT1) in 95 patients using 1.5 (42 patients) and 3 T (53 patient). Two independent readers analyzed all studies and the examinations were presented in anonymized and random fashion for a total of 190 interpretations per observer. One reader had more than 20 years of experience and the second reader had 1 year of experience.

RESULTS

The least experienced observer found 542 brain metastases on postcontrast non-MIP 3DT1W and 605 with the MIP-3DT1 technique. For this observer, use of MIP resulted in increased number of detected metastases in 36% of patients regardless of field strength. The more experienced observer found 589 brain metastases on non-MIP 3DT1W and 621 with the MIP-3DT1 technique and the use of the latter also resulted in increased detection of metastases in 33% of patients regardless of field strength.

CONCLUSIONS

In our study, we found that using MIP-3DT1 reconstructions of previously obtained postcontrast 3DT1W improved detection of brain metastases. This improvement was experienced by both the junior and experienced neuroradiologists and was also better at 3.0 T than at 1.5 T.

Quiet T1-weighted imaging using PETRA: initial clinical evaluation in intracranial tumor patients

PURPOSE

To compare the lesion contrast and signal to noise ratio (SNR) obtained with T1-weighted pointwise encoding time reduction with radial acquisition (PETRA) to those of Magnetization-Prepared RApid Gradient-Echo (MPRAGE) for contrast-enhanced imaging of primary and metastatic intracranial tumors, and to investigate whether PETRA is able to reduce acoustic noise for improved patient comfort.

MATERIALS AND METHODS

Fifteen patients with intracranial tumors underwent 3 Tesla MRI including inversion-prepared PETRA and MPRAGE. The two sequences had comparable scan times, spatial resolution and spatial coverage. "Tumor conspicuity" was rated qualitatively by two radiologists, while enhancing lesion-to-white matter contrast to noise ratio (CNR) and white-matter SNR were analyzed quantitatively using paired t-tests. The acoustic noise generated by each sequence was measured.

RESULTS

Qualitative rating of "tumor conspicuity" by two radiologists resulted in nearly identical average scores for the two sequences. Quantitative analyses revealed that (i) there was no significant difference between the mean CNR values of the two sequences (P = 0.57), (ii) the mean SNR of PETRA was significantly higher than that of MPRAGE (P < 0.01), and (iii) the mean sound level of PETRA was significantly lower than that of MPRAGE (P < 0.01).

CONCLUSION

Inversion-prepared PETRA was found to be viable as a quiet alternative to MPRAGE for contrast-enhanced T1-weighted studies of intracranial tumors.

Imaging of brain metastases

Imaging plays a key role in the diagnosis of central nervous system (CNS) metastasis. Imaging is used to detect metastases in patients with known malignancies and new neurological signs or symptoms, as well as to screen for CNS involvement in patients with known cancer. Computed tomography (CT) and magnetic resonance imaging (MRI) are the key imaging modalities used in the diagnosis of brain metastases. In difficult cases, such as newly diagnosed solitary enhancing brain lesions in patients without known malignancy, advanced imaging techniques including proton magnetic resonance spectroscopy (MRS), contrast enhanced magnetic resonance perfusion (MRP), diffusion weighted imaging (DWI), and diffusion tensor imaging (DTI) may aid in arriving at the correct diagnosis. This image-rich review discusses the imaging evaluation of patients with suspected intracranial involvement and malignancy, describes typical imaging findings of parenchymal brain metastasis on CT and MRI, and provides clues to specific histological diagnoses such as the presence of hemorrhage. Additionally, the role of advanced imaging techniques is reviewed, specifically in the context of differentiating metastasis from high-grade glioma and other solitary enhancing brain lesions. Extra-axial CNS involvement by metastases, including pachymeningeal and leptomeningeal metastases is also briefly reviewed.

Contrast-enhanced MR imaging of metastatic brain tumor at 3 tesla: utility of T(1)-weighted SPACE compared with 2D spin echo and 3D gradient echo sequence

We evaluated the newly developed whole-brain, isotropic, 3-dimensional turbo spin-echo imaging with variable flip angle echo train (SPACE) for contrast-enhanced T(1)-weighted imaging in detecting brain metastases at 3 tesla (T). Twenty-two patients with suspected brain metastases underwent postcontrast study with SPACE, magnetization-prepared rapid gradient-echo (MP-RAGE), and 2-dimensional T(1)-weighted spin echo (2D-SE) imaging at 3T. We quantitatively compared SPACE, MP-RAGE, and 2D-SE images by using signal-to-noise ratios (SNRs) for gray matter (GM) and white matter (WM) and contrast-to-noise ratios (CNRs) for GM-to-WM, lesion-to-GM, and lesion-to-WM. Two blinded radiologists evaluated the detection of brain metastases by segment-by-segment analysis and continuously-distributed test. The CNR between GM and WM was significantly higher on MP-RAGE images than on SPACE images (P<0.01). The CNRs for lesion-to-GM and lesion-to-WM were significantly higher on SPACE images than on MP-RAGE images (P<0.01). There was no significant difference in each sequence in detection of brain metastases by segment-by-segment analysis and the continuously-distributed test. However, in some cases, the lesions were easier to detect in SPACE images than in other sequences, and also the vascular signals, which sometimes mimic lesions in MP-RAGE and 2D-SE images, were suppressed in SPACE images. In detection of brain metastases at 3T magnetic resonance (MR) imaging, SPACE imaging may provide an effective, alternative approach to MP-RAGE imaging for 3D T(1)-weighted imaging.

[Silent brain metastasis in the initial staging of lung cancer: evaluation by computed tomography and magnetic resonance imaging]

OBJECTIVE

Brain metastases are common in patients with lung cancer and influence both prognosis and treatment decisions. The aim of this study was to evaluate the incidence of silent brain metastasis during the initial staging of lung cancer using cranial computed tomography (CT) and magnetic resonance imaging (MRI).

PATIENTS AND METHODS

We performed a retrospective analysis of lung cancer patients with no neurologic signs or symptoms who were evaluated by cranial CT, MRI, or both at the time of diagnosis. Results were checked using data obtained during systematic monitoring of progression. The incidence of brain metastasis was analyzed by sex, age, histology, and TNM stage.

RESULTS

Silent brain metastasis was detected in 8.3% of the 169 patients with lung cancer. The detection rate was 7.9% in the cranial CT group and 11.3% in the cranial MRI group. The percentage of false positives and false negatives was 0% and 1.9%, respectively. Cranial MRI performed better than CT in detecting multiple brain metastases (72.8% vs 50%) and metastases smaller than 1 cm (36.3% vs 16.7%). The incidence of brain metastasis was lower in patients aged over 70 years and higher in patients with adenocarcinoma (20% compared to 5.3% to 5.9% for other histologic subtypes, P=.01). No association was found with TNM stage.

CONCLUSIONS

The incidence of silent brain metastasis is high in patients under 70 years of age, particularly in patients with adenocarcinomas, even in initial stages. This should be taken into consideration when planning staging procedures. Cranial MRI seems to be more accurate than cranial CT for detecting multiple metastases and small metastases.

S-100B and FDG-PET/CT in Therapy Response Assessment of Melanoma Patients

OBJECTIVE

To compare the value of the tumor marker S-100B protein and fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in patients treated for melanoma metastases.

METHODS

In 41 patients with proven melanoma metastases, S-100B measurements and FDG-PET/CT were performed before and after therapy. The change of S-100B levels (DeltaS-100B) was assessed. In all patients, therapy response was assessed with PET/CT using visual criteria and change of maximal standard uptake value (DeltaSUV(max.)) or total lesion glycolysis (DeltaTLG).

RESULTS

In 15 of 41 patients (37%), S-100B values were not suitable because they were normal before and after therapy. In 26 patients, S-100B was suitable for therapy response assessment. PET/CT was suitable for response assessment in all patients. Correlations between DeltaS-100B and DeltaTLG (r = 0.850, p < 0.001) and between DeltaS-100B and DeltaSUV(max.) (r = 0.818, p < 0.001) were both excellent. A complete agreement between S-100B and PET/CT response assessment was achieved in 22 of 26 patients. In 4 patients, therapy response differed between the S-100B and PET/CT findings, but subsequent S-100B measurements realigned the S-100B results with the later PET/CT findings.

CONCLUSION

In a third of our patients with metastases, the S-100B tumor marker was not suitable for therapy assessment. In these patients, imaging techniques remain necessary, and FDG-PET/CT can be used for response assessment.

Tumour assessment in advanced melanoma: value of FDG-PET/CT in patients with elevated serum S-100B

PURPOSE

To evaluate the usefulness of PET/CT in melanoma patients with an elevated serum S-100B tumour marker level.

METHODS

Out of 165 consecutive high-risk melanoma patients referred for PET/CT imaging, 47 had elevated (>0.2 microg/l) S-100B serum levels and a contemporaneous 18F-FDG PET/CT scan. PET/CT scans were evaluated for the presence of metastases. To produce a composite reference standard, we used cytological, histological, MRI and PET/CT follow-up findings as well as clinical and S-100B follow-up.

RESULTS

Among the 47 patients with increased S-100B levels, PET/CT correctly identified metastases in 38 (30 distant metastases and eight lymph node metastases). In one patient with cervical lymph node metastases, PET/CT was negative. Eight patients had no metastases and PET/CT correctly excluded metastases in all of them. Overall sensitivity for metastases was 97% (38/39), specificity 100% (8/8) and accuracy 98% (46/47). S-100B was significantly higher in patients with distant metastases (mean 1.93 microg/l, range 0.3-14.3 microg/l) than in patients with lymph node metastases (mean 0.49 microg/l, range 0.3-1.6 microg/l, p=0.003) or patients without metastases (mean 0.625 microg/l, range 0.3-2.6 microg/l, p=0.007). However, 6 of 14 patients with a tumour marker level of 0.3 microg/l had no metastases.

CONCLUSION

In melanoma patients with elevated S-100B tumour marker levels, FDG-PET/CT accurately identifies lymph node or distant metastases and reliably excludes metastases. Because of the significant number of false positive S-100B tumour marker determinations (17%), we recommend repetition of tumour marker measurements if elevated S-100B levels occur before extensive imaging is used.

Imagerie des métastases intracrâniennes chez l’adulte

Intracranial metastases account for up to 35% of intracranial tumors in adult. They can involve any part of the central nervous system: brain, meninges and cranial nerves. Any systemic tumor can metastasize to the brain; the most common primaries include lung, breast and melanoma. Imaging plays a major role in the evaluation and management of patients with metastatic brain tumors. This article discusses optimal CT and MR imaging protocols and describes imaging features and distinguishing characteristics of cerebral and meningeal metastases.

Comparative study of vascular enhancement on post-contrast CT using three dosages of iodinated contrast media for the aim of detecting brain metastasis in patients with lung cancer

OBJECTIVE

A prospective double-blind randomized study was performed to compare the contrast of vascular enhancement using three dosages of iodinated contrast media for a possible metastatic lesion in the brain.

MATERIALS AND METHODS

Sixty-six patients with lung cancer received brain computed tomography (CT) with intravenous administration of iodinated contrast medium (CM). The patients were randomly assigned to receive one of the three types of CM: 30 g iodine, 24 g iodine, and 15 g iodine. Three radiologists judged the degree of vascular contrast enhancement and diagnosed the presence of brain metastasis. The CT numbers in major arteries were also measured.

RESULTS

The subjective average scores with standard deviation were 2.06+/-0.48, 1.97+/-048, and 1.44+/-0.43, and the measured average CT numbers with standard deviation (SD) were 168.5+/-39.6, 166.1+/-28.6, and 146.1+/-27.0 HU with 30 g, 24 g, and 15 g iodine, respectively. The scores and the CT numbers in 15 g iodine were less than those with 30 g and 24 g iodine. Brain metastasis was detected in one patient each in groups A and C, and one false-positive case was found in group B.

CONCLUSION

CT study with a dose of 24 g iodine showed equivalent quality on vascular enhancement in comparison with a 30 g iodine dose.

Treatment options for brain metastases from melanoma

Brain metastases are a common complication of metastatic malignant melanoma, conferring an exceedingly poor prognosis. Diagnosis of brain metastasis often has significant implications for duration and quality of life, and management can be difficult due to rapid progression of disease and resistance to conventional therapies. This review focuses primarily on the published evidence for treatment modalities for brain metastases from melanoma, emerging technologies and outlines future directions for research. In summary, external-beam radiation alone appears effective in palliating symptoms. Surgical management of solitary or acutely symptomatic lesions appears to alleviate symptoms and provide the possibility of local control of disease. Stereotactic radiosurgery is an increasingly utilized technique for patients with a limited number of metastases and presents a less-invasive alternative to craniotomy. Chemotherapy alone is relatively ineffective, although combined chemotherapy with external-beam radiation is being investigated. Future directions include combined modality therapy, the incorporation of novel agents and careful consideration of the structure of clinical trials for this disease.

Adults and children with headache: evidence-based diagnostic evaluation

Headache represents one of the most common complaints in the outpatient and emergency room setting [1]. Most causes of headache are benign and do not require emergent imaging or intervention. The authors' review of the diagnostic tests does not offer absolute indications for neuroimaging because most of the evidence is based on studies that are not randomized controlled trials. Imaging guidelines for adults and children, however, have emerged based on the available level 2 and 3 literature. CT imaging remains the initial test of choice for new-onset headache in adults and headache suggestive of SAH. Most of the available literature also recommends performing lumbar puncture when CT is equivocal in ruling out SAH [1]. The sensitivity of MR imaging appears to be less than CT for SAH [1]. Newer MR imaging techniques need to be tested and developed to determine if they have higher sensitivity than CT or lumbar puncture in the detection of SAH. In adults with suspected brain metastatic disease, contrast-enhanced MR imaging is the imaging study of choice [38,39]. Contrast-enhanced MR imaging is the examination of choice for brain metastatic lesions less than 2 cm [39]. CT angiography and MR angiography have sensitivities greater than 85% for brain aneurysms larger than 5 mm [43]. If clinically warranted, aneurysms smaller than 5 mm may require digitally subtracted angiography because of the low sensitivity of MR and CT angiography. In children, the choice of diagnostic test strategy depends on the risk group. In high-risk patients, MR imaging is the test of choice whereas in low-risk patients, close clinical observation with periodic reassessment is the best strategy [44]. Clinical diagnosis will always play a key role in the evaluation of headache disorders; however, for the small subset of patients who present with headache secondary to an intracranial space-occupying lesion, bleeding, or SAH, making the diagnosis is crucial to decreasing morbidity and mortality. CT, MR imaging, and lumbar puncture play important roles in the assessment of headache disorders, but their future roles will continue to evolve as the technology becomes more sophisticated and robust, and physicians become more expert with their use [1].

Brain metastases

Brain metastases are one of the most feared complications of cancer because even small tumors may cause incapacitating neurologic symptoms. This article reviews the epidemiology, clinical features, treatment, and prognosis of brain metastases from system malignancies.

Extra-thoracic staging of lung cancer

This article reviews the staging of extra-thoracic metastatic lung cancer. The imaging strategy, including when to screen as well as the different modalities available for different sites of spread of disease are discussed. The emerging role of whole body positron emission tomography in screening for metastases is also explored.

Diagnostic accuracy of MRI compared to CCT in patients with brain metastases

OBJECTIVES

In patients with extracranial neoplasms, the occurrence and number of brain metastases (BM) are critical for further diagnostic approaches and therapeutic strategies and the patient's prognosis. Although widely accepted, there is surprisingly little evidence in the literature that MRI is superior to CCT. Therefore, in patients with solitary BM according to diagnostic contrast-enhanced computed tomography (CCT), we investigated, what additional information could be gained by contrast-enhanced magnetic resonance imaging (MRI).

METHODS/RESULTS

Among 55 patients with solitary BM according to CCT, 17 had multiple BM on MRI (31%) and 38 had solitary BM in both. Based on a presumed binomial distribution of our data, we calculated a rate of at least 19% of patients with solitary BM on CCT, in which MRI would show multiple lesions (p = 0.05). The two main characteristics for BM missed by CCT were the smaller diameter, which averages 2 cm less than in BM identified with both modalities, and a preferential frontotemporal location.

CONCLUSION

MRI is indeed superior to CCT in the diagnosis of BM the essential reasons besides detection of smaller lesions being a better soft tissue contrast, significantly stronger enhancement with paramagnetic contrast agents, the lack of bone artifacts, fewer partial volume effects, and direct imaging in three different planes. Therefore, MRI is indispensable in the diagnostic workup of patients with BM for choosing the optimum therapeutic approach, especially with regard to the decision whether to operate or to primarily irradiate the patient's metastases.

Detection of brain metastasis in potentially operable non-small cell lung cancer: a comparison of CT and MRI

STUDY OBJECTIVE

To compare the usefulness of MRI and CT in the detection of brain metastases during preoperative evaluation and postoperative follow-up.

DESIGN

A prospective and sequential comparison.

PATIENTS AND METHODS

Of 332 patients with potentially operable non-small cell lung cancer who were free of neurologic signs and symptoms, brain CT was performed preoperatively on 155 patients (CT group) and brain MRI on 177 patients (MRI group). Patient characteristics in both groups were comparable. In 279 patients with complete resection of the primary lung tumor, intensive follow-up with CT and MRI was performed in the respective groups. The preoperative detection of brain metastases, postoperative intracranial recurrence rates, and characteristics of detected brain tumors were compared between the two groups. The survival of patients with brain metastases was also compared.

RESULTS

From the first evaluation to 12 months after surgery for primary lung cancer, brain metastases were observed in 11 patients (7.1%) from the CT group and 12 patients (6.8%) from the MRI group. MRI detected brain metastases preoperatively in 6 of the 12 patients (3.4% of the total MRI group), whereas CT detected brain metastases preoperatively in 1 of the 11 patients (0.6% of the total CT group). MRI showed a tendency toward a higher preoperative detection rate of brain metastases than CT (p = 0.069). Furthermore, the mean (+/- SD) maximal diameter of the brain metastases was significantly smaller in the MRI group (12.8+/-9.1 mm) than in the CT group (20.3+/-7.0 mm) (p = 0.041). However, the median survival time and 2-year survival rate after treatment of detected brain metastases, respectively, were 10 months and 27% in the CT group and 17 months and 28% in the MRI group. There was no significant difference between the groups in survival time.

CONCLUSIONS

Preoperative evaluation and intensive follow-up with MRI could facilitate early detection of brain metastases in patients with potentially operable lung cancer. However, further studies on detection and treatment of the metastatic tumors are considered necessary.

Cerebral metastases of alveolar rhabdomyosarcoma in an infant with multiple skin nodules

PURPOSE

This report describes extremely rare cases of infantile rhabdomyosarcoma with multiple skin nodules. They are of interest not only for their anatomic sites, but also for subsequent cerebral metastases with sudden cranial hypertension.

PATIENTS

Two infants had multiple skin nodules and excisional biopsy revealed alveolar type rhabdomyosarcomas. The patients were treated with tumor resection and combined chemotherapy without any clinical progression for 9 and 16 months, respectively.

RESULTS

Evidence of cerebral metastases developed with sudden vomiting and convulsion as the first manifestation. In one patient, urgent radiographic examinations failed to reveal lesions except for dilated cerebral ventricles. Seven weeks after the onset of the neurologic symptoms, only Gd-DPTA-enhanced magnetic resonance imaging (MRI) revealed multiple punctate metastatic lesions hyperintense to the surrounding cerebral tissue. Despite appropriate chemotherapy, both patients had disease progression and died of central nervous system metastases.

CONCLUSIONS

The authors emphasize the need to recognize the multiple cutaneous presentation of infantile rhabdomyosarcoma and the association of cerebral metastases as a potential and fatal complication. The diagnosis is facilitated by Gd-DPTA-enhanced MRI, particularly when cerebral computed tomography scans fail to disclose metastatic lesions.

Cost of patient follow-up after potentially curative lung cancer treatment

The two objectives of this study were to determine the range of recommended follow-up strategies for patients with lung cancer treated with curative intent and to estimate the cost of such follow-up. Ten articles delineating eight specific follow-up strategies were identified from a Medline search of the literature for 1980 through 1995. An economic analysis was done of the costs associated with the identified strategies. Charge data obtained from the Part B Medicare Annual Data file and the Hospital Outpatient Bill file were used as a proxy for cost. Follow-up intensity varied widely across strategies for 5 years of posttreatment follow-up. Medicare-allowed charges for 5-year follow-up ranged from a low of $946 to a high of $5645. When Medicare-allowed charges were converted to a proxy for actual charges by a conversion ratio of 1.62, the range was $1533 to $9145, a fivefold difference in charges. There was no indication that more intensive, higher-cost strategies increased survival or quality of life. The published literature, including textbooks, holds few answers in this area.

Brain metastasis in resected lung cancer: value of intensive follow-up with computed tomography

BACKGROUND

Brain metastases are a common mode of recurrence in resected lung cancer and are usually associated with an ominous outcome.

METHODS

To assess the usefulness of follow-up using computed tomography of the brain for early detection and effective treatment of brain metastases, we prospectively studied 128 patients with completely resected non-small cell lung cancer. Follow-up computed tomographic scans were obtained every 2 to 6 months over 24 postoperative months in 69 patients and every 2 months for 6 postoperative months in 59.

RESULTS

Brain metastases were discovered in 11 patients (8.6%), and 7 patients were neurologically asymptomatic when the metastases were diagnosed. Single metastasis was found in 5 patients and multiple metastases in 6. The maximal size of all but one lesion was less than 25 mm. The median survival time and 5-year survival rate in all 11 patients with brain metastases were 10 months and 24%, respectively. Furthermore, those in 7 asymptomatic patients were 25 months and 38%, respectively.

CONCLUSIONS

We consider intensive follow-up with computed tomography to be worthwhile for early detection and effective treatment of brain metastases in patients with completely resected lung cancer.

Metástase cerebral: tratamento paliativo com radiocirurgia

O artigo faz avaliação de 52 pacientes com metástase cerebral tratados com radiocirurgia estereotática na Universidade McGill, em Montreal. A radiocirurgia foi realizada com a técnica dinâmica em que, ao mesmo tempo, giram a mesa e a cabeça do acelerador linear de 10 MV. Todos os pacientes (56 tratamentos ao todo) foram tratados com um único isocentro e uma dose única mediana de 1800 cGy na periferia da metástase. Em 88% dos casos a radiocirurgia foi usada após falha de tratamento radioterápico fracionado em todo cérebro. Todos os 52 casos tiveram avaliação com CT pós radiocirurgia. O seguimento mediano foi de 6 meses (variou entre 1 e 37 meses) e a taxa de resposta, parcial ou completa, foi de 64%. Apenas 4 pacientes (7%) tiveram algum tipo de complicação tardia relacionada ao tratamento. Estes achados vão de encontro com dados da literatura. A radiocirurgia é tratamento pouco agressivo, bem tolerado e com alta taxa de resposta para lesões locais e pode ser útil para pacientes selecionados. O seu valor definitivo, como tratamento único ou combinado com radioterapia em todo cérebro, está sendo avaliado de forma prospectiva e randomizada.

Invited review: biophysical properties and clinical applications of magnetic resonance imaging contrast agents

Contrast enhanced magnetic resonance imaging (MRI) is a very versatile and effective technique for detecting and characterizing lesions, for identifying a variety of patho-physiological abnormalities, and for providing perfusion and functional information. The application of contrast enhanced MRI to many clinical and research indications has emerged because of the rapid evolution in imaging techniques, improved methodology, and the development of efficient and specific contrast agents. Problems related to optimizing parameters and dosage have been due to complex interplay of relaxation times, biophysical mechanisms and acquisition parameters. A knowledge of basic biophysical aspects is therefore essential for a full understanding of the results obtained for different organs under different conditions, and for optimizing the image parameters and dosage of contrast agents. This article underlines the biophysical basis of the effects of contrast agents in MRI, identifies the problems involved in optimizing the parameters for maximum efficiency, and presents a general overview of the clinical studies and research applications in the central nervous system, perfusion abnormalities, hepatobiliary system, musculoskeletal system and the gastrointestinal tract. The section on perfusion studies includes a discussion of quantitative analysis and kinetic models describing the effects of contrast agents. Finally, a critical evaluation of the scope and limitations of contrast enhanced MRI is presented.

Management of brain metastases

Brain metastases usually develop in patients with disseminated systemic disease. Effective palliation is available for the vast majority of patients with brain metastases, but many will die within 6 months, usually from progressive systemic tumor. However, in a substantial proportion of patients, a vigorous therapeutic approach using surgery, radiotherapy, and possibly chemotherapy leads to years of productive life. Recurrent brain metastases can often be retreated using newer techniques of brachytherapy and stereotactic radiosurgery as well as conventional treatments. Brain metastases do not necessarily mean imminent death for every patient, and physicians can now offer patients a growing range of therapeutic options. Furthermore, attention to symptomatic therapies can improve the quality of life for all patients, even those whose survival will be relatively short.

Diagnostic tests for lung cancer

The goals of diagnostic testing in patients with suspected lung cancer are to establish the diagnosis and to determine the stage of the disease so that appropriate therapy can be initiated. Unless a patient has hemoptysis, fever, or a change in cough as an initial manifestation, resectable lung cancer will seldom be diagnosed on the basis of the history. Screening tests--particularly chest roentgenography--have usually identified the abnormality. The managing physician should then select diagnostic procedures that are associated with low risk and that will provide further diagnostic and staging information. A biopsy will almost always be necessary before definitive therapy can be planned. In many cases, a single procedure--for example, a needle biopsy of a hepatic lesion or biopsy of a supraclavicular lymph node--will provide a definitive diagnosis and establish the stage of the disease. The roles of cytology, histopathologic examination, radiologic studies, and various types of biopsy in the diagnosis of lung cancer are reviewed in this report.

CT characteristics of patients with brain metastases treated in RTOG study 79-16

The search continues for a favorable subgroup of patients with brain metastases in whom testing of new modalities might show a benefit in overall survival. Complete pre- and post-treatment CT evaluation of the brain was performed in 779 of the 859 patients entered into RTOG protocol 7916, a phase III study of the role of misonidazole combined with radiation therapy in the treatment of brain metastases. Pretreatment scan findings of mass effect, midline shift, massive edema, central necrosis, location of sentinel lesion, and number of lesions were correlated with length of survival for all patients as well as for each treatment group. The only characteristics that showed a statistically significant difference in survival in the overall group were the presence of < or = 3 lesions and the presence of a midline shift. The actual benefit in overall survival, however, was found to be only 3 weeks. The volume of the largest lesion prior to treatment did not correlate well with survival, nor did location of lesions. The time to response, number of responders and absolute decrease in number of lesions were similar for the four treatment arms. Patients who responded to cranial treatment had a significantly prolonged survival over those who did not respond. No CT characteristic evaluated in this study showed value as a clinically relevant prognosticator for patients with brain metastases for the overall group. Patients who fulfilled three of the four favorable clinical characteristics previously described by Diener-West (age < or = 60, KPS > or = 70, primary lesion absent or controlled and brain as sole site of metastasis), were analyzed separately. Those with < or = three lesions had a statistically significantly prolonged survival over those with four or more lesions.

Configurational MR characteristics of metastatic brain tumors

Magnetic resonance (MR) characteristics of metastatic brain tumors (MBTs) were studied using 15 cases (13 males and 2 females whose ages ranged from 32-78 yr, with the mean age of 57.8 yr; 12 adenocarcinomas, 2 squamous-cell carcinomas, 2 large-cell carcinomas). Nine cases showed hypointensities and five showed isointensities on T1-weighted images. Six cases showed markedly hypo- or hypointensities, two showed isointensities, and six showed markedly hyper- or hyperintensities on T2-weighted images. One case was markedly hyperintense on both T1- and T2-weighted images. The decrease of the signal intensity on the T2-weighted image was the main MR characteristic. A hypointense peritumoral rim was seen in four of the six hyperintense tumors on T2-weighted images. There was no correlation between the signal intensity and the histological classification.

Identification of intracranial liqor metastases of experimental stereotactically implanted brain tumors by the tumor-selective MRI contrast agent MnTPPS

Two cases of stereotactically induced and spontaneously metastasizing neoplasms in the rat and the cat brain are reported. In the rat, a malignant Schwannoma derived from initially supratentorially implanted RN6 cells developed a second tumor in the posterior cranial fossa. In the cat, a highly malignant polymorphous anaplastic glioma induced by implantation of cloned rat glioma cells (F98) into the left internal capsule developed small tumor cell nests along the ependyma of the ipsilateral ventricle. In precontrast magnetic resonance imaging (MRI) of both cases, the primary tumor was detectable only by a very weak hypointensity and through a shift of the midline. No metastases were apparent. Application of the metallated paramagnetic porphyrin derivative manganese(III) tetraphenylporphine sulfonate (MnTPPS) resulted in a remarkable contrast enhancement between tumoral and normal tissue, which was evident not only in the primary tumor but also in the small metastases. These observations demonstrate for the first time that MnTPPS is an efficient MRI contrast agent for the detection of metastases from primary brain neoplasms and, in consequence, support the hypothesis of its selective binding to tumor cells.

The clinical application of radiopharmaceuticals

This article highlights the choices and the arguments in the selection of appropriate contrast materials in radiological examinations--nonionic versus ionic contrast material--and aims to assist the physician in decision-making. Various authors have raised questions concerning the proposed advantages of nonionic contrast material. However, studies in low risk patients have shown more complications with the use of ionic contrast than nonionic contrast materials; this is the important group of patients since in high risk patients nonionics are used almost exclusively. The important factor that increases the controversy is cost, which is significant since nonionic agents cost 10 to 15 times more than ionic agents in the USA. Thus, cost-benefit considerations are important because price sensitivity and cost may determine fund availability for equipment or materials that also may be necessary or important in improving patient care. In magnetic resonance imaging (MRI), as in computed tomography (CT), the use of contrast material has improved diagnostic accuracy and the ability to reveal lesions not otherwise easily detected in brain and spinal cord imaging. These include separating scan from disc, meningitis, meningeal spread of tumour, tumour seeding, small metastases, intracanalicular tumours, separating major mass from oedema, determining bulk tumour size and ability to demonstrate blood vessels so dynamic circulatory changes may be revealed.

Comparison of spin echo T1-weighted and FLASH 90 degrees gadolinium-enhanced magnetic resonance imaging in the detection of cerebral metastases

A direct comparison of post-gadolinium FLASH 90 degrees magnetic resonance (MR) images against conventional post-gadolinium T1-weighted spin echo MR images obtained in patients with suspected cerebral metastatic disease shows the FLASH sequence to be inferior. False negative FLASH 90 degrees gadolinium-enhanced MR scans are thought to be a result of either magnetic susceptibility artefact or inferior contrast resolution. False positive FLASH 90 degrees gadolinium-enhanced MR images are a result of either difficulty in interpreting the high signal seen in small vessels or, again, magnetic susceptibility effects. In addition, our study shows small abnormalities suggestive of cerebral metastases on the FLASH 90 degrees gadolinium-enhanced sequences which were not seen on the spin echo T1-weighted gadolinium-enhanced sequences. We believe that spin echo T1-weighted gadolinium-enhanced MR sequences demonstrated 131 out of 139 (94.2%) and FLASH 90 degrees gadolinium-enhanced MR sequences detected 122 out of 139 (87.8%) possible metastases. From this, we conclude that spin echo T1-weighted gadolinium-enhanced MR sequences is a better test than FLASH 90 degrees gadolinium-enhanced MR in the diagnosis of brain metastases and that either sequence alone is limited as a screening test.

Magnetic resonance imaging in the evaluation of lung cancer

MRI is used most efficaciously in the evaluation of patients with bronchogenic carcinoma when employed as a tailored examination designed to answer specific questions relevant to patient management. CT continues to be used more generally in staging lung cancer when imaging beyond conventional chest radiography is required. Specific areas in which MRI can provide important and unique information (which may supplement a CT study) include the following: (1) evaluation of the local extent of superior sulcus tumors, and (2) distinction between stage IIIA (resectable) and stage IIIB (unresectable) tumors. Confirmation of tumor invasion of major mediastinal structures is necessary before depriving a patient of potential curative resection. MRI may contribute important information when CT findings are indefinite, particularly with regard to invasion of major cardiovascular structures (eg, superior vena cava, pulmonary artery, pericardium, and heart); invasion of the tracheal carina or bilateral involvement of main bronchi; and the presence of contralateral mediastinal or hilar lymphadenopathy. MRI should be considered as a primary imaging modality to evaluate central tumors in patients for whom intravenous contrast agents are contraindicated, and as a problem-solving modality when CT is inconclusive in the detection of a possible hilar or mediastinal mass. Other specific applications of MRI include the identification of tumor recurrence in the presence of radiation fibrosis, assessment of the extent of chest wall invasion of peripheral lung tumors, and the noninvasive characterization of adrenal masses. The scope of these MRI applications in patients with lung cancer may expand in the future with refinements in motion suppression techniques, implementation of ultrafast MRI (using variations of the echoplanar method), and further development of MRI spectroscopy and MRI contrast agents.

The prospective evaluation of Gd-DTPA in 225 consecutive cranial cases: adverse reactions and diagnostic value

This prospective study evaluates two facets of gadopentetate dimeglumine (Gd-DTPA) enhanced MR imaging in 225 consecutive cranial cases in patients greater than 18 years of age: (i) patient and physician perception of adverse reactions, (ii) diagnostic value of the Gd-DTPA enhanced exam. The 225 cases included 173 head cases, 27 IAC cases, and 25 sella cases. Forty-six percent of the cases were abnormal excluding cases of mild atrophy and ischemic white matter disease judged to be related to aging and not pertinent to the patient's presenting complaint. Concerning adverse reactions, 83% of patients had no complaints. Five percent of the patients had reactions that were judged by the physician to be related to Gd-DTPA. All reactions were minor and required no therapy. In a subset of exams (115) that were blindly and independently interpreted by two board-certified, fellowship-trained radiologists, the Gd-DTPA-enhanced exam resulted in a change in diagnosis in 5%-8% of cases. Additionally, a major benefit of Gd-DTPA administration was the increased diagnostic confidence afforded by the addition of a contrast enhanced exam due to improved lesion characterization and exclusion of additional significant intracranial pathology. In 52%-69% of the abnormal cases, Gd-DTPA provided additional diagnostic information and in 26%-39% the absence of enhancement aided in interpretation. The Gd-DTPA-enhanced exam aids in the diagnosis and characterization of neoplastic disease, acoustic neuroma, subacute infarction, inflammatory disease (meningeal and parenchymal), and certain vascular abnormalities.

New applications of MR contrast agents in neuroradiology

Contrast enhancement has now become an integral part of MR imaging. In this paper, the current uses of contrast agents in MR imaging of both the head and spine are reviewed. In addition, new applications of contrast in MR imaging, including some more current and controversial, are also explored.

Value of contrast enhanced CT scanning in the non-trauma emergency room patient

To determine the value of performing contrast CT in addition to non-contrast CT in the evaluation of acute non-traumatic central nervous system disorders, we retrospectively reviewed 322 cases originating from the emergency room at our institution. The most common indication for scanning was seizure activity (34% of total), followed by headache (30%), focal neurological deficit (10%), and altered mental status (8%). 75% of the non-contrast scans were normal. The contrast-enhanced scan revealed abnormalities not evident on the non-contrast scan in only three of these cases, and the information did not alter patient management. We conclude that in the acute setting, if a non-contrast CT is normal, a contrast study is usually unnecessary. Therefore, given the additional risks of contrast infusion, the contrast study, if needed, is generally best obtained at a later date, after more careful evaluation of the patient's history and medical records. If the non-contrast CT scan is abnormal, a contrast enhanced CT scan may be beneficial, but, again, is often not needed to direct acute patient management.

Imaging of brain metastases. Comparison of computerized tomography (CT) and magnetic resonance imaging (MRI)

For the demonstration of brain metastases both CT and MRI are available as diagnostic modalities. To compare both imaging methods as to their sensitivity in detecting brain metastases CT scans and MR images of 60 patients with suspected brain metastases were evaluated. Comparing contrast-enhanced CT and plain MRI neither modality was found to be clearly superior in this respect.

State-of-the-art assessment. Diagnostic oncologic imaging

This review has summarized the status of organ site cancer imaging as applied to tumor detection, staging, and posttreatment follow-up. More general questions which have not been addressed include those related to the following: (1) the problem of providing more adequate training of radiologists in the specific challenge of cancer imaging; (2) how to increase the awareness of oncologists as to the specific indications and applications of tumor imaging procedures and enhance joint communication between radiologists and clinicians in the planning of the imaging procedures; and (3) how to stimulate the radiology and oncology communities to establish imaging standards and recommended procedures for specific tumor imaging challenges. Hopefully, an appreciation of the complex challenge of cancer imaging will result from these and subsequent discussions.