Pulmonary metastases: MR imaging with surgical correlation--a prospective study

Chest Magnetic Resonance Imaging: Advances and Clinical Care

Many promising study results as well as technical advances for chest magnetic resonance imaging (MRI) have demonstrated its academic and clinical potentials during the last few decades, although chest MRI has been used for relatively few clinical situations in routine clinical practice. However, the Fleischner Society as well as the Japanese Society of Magnetic Resonance in Medicine have published a few white papers to promote chest MRI in routine clinical practice. In this review, we present clinical evidence of the efficacy of chest MRI for 1) thoracic oncology and 2) pulmonary vascular diseases.

Lung Magnetic Resonance Imaging: Technical Advancements and Clinical Applications

ABSTRACT

Since lung magnetic resonance imaging (MRI) became clinically available, limited clinical utility has been suggested for applying MRI to lung diseases. Moreover, clinical applications of MRI for patients with lung diseases or thoracic oncology may vary from country to country due to clinical indications, type of health insurance, or number of MR units available. Because of this situation, members of the Fleischner Society and of the Japanese Society for Magnetic Resonance in Medicine have published new reports to provide appropriate clinical indications for lung MRI. This review article presents a brief history of lung MRI in terms of its technical aspects and major clinical indications, such as (1) what is currently available, (2) what is promising but requires further validation or evaluation, and (3) which developments warrant research-based evaluations in preclinical or patient studies. We hope this article will provide Investigative Radiology readers with further knowledge of the current status of lung MRI and will assist them with the application of appropriate protocols in routine clinical practice.

MR imaging of the chest in children

The application of magnetic resonance imaging (MRI) to diseases of the pediatric chest has been complicated, selective and cautious. More specifically, MRI of the pediatric lung has been a highly anticipated technique that has inherent great potential for improved imaging of the chest without the use of ionizing radiation. Practical issues impede the transition from multidetector computed tomography (MDCT) to MRI in some chest diseases in children, while other disease states are intrinsically easier to image using MRI. More rapid respiratory and cardiac rates, patient instability, sedation requirements, and the low physical density of water in the lung, hinder the requirement for maximal spatial and contrast resolution. This review is intended to serve as a functional review of the practical and currently applicable ways in which the transition of imaging the non-cardiac aspects of the pediatric chest from MDCT to MRI can be done in a clinically useful way.

Optimal management of pulmonary metastases from colorectal cancer

The incidence of colorectal cancers is rising worldwide and pulmonary metastases were seen in approximately 10-15% of all patients. Surgical metastasectomy is a widely accepted procedure in selected patients and is considered as the only curative option in patients with secondary pulmonary malignancy. But surgical resection remains controversial due to the lack of randomized trials, comparing pulmonary metastasectomy to control, either medical therapy, or observation. This article will discuss the differentiated therapeutic strategies for patients with pulmonary metastases of colorectal cancer, focusing on surgical resection, patient evaluation, prognostic factors, interdisciplinary therapeutic approaches and current trials.

Magnetic resonance imaging of the chest: current and new applications, with an emphasis on pulmonology

The objective of the present review study was to present the principal applications of magnetic resonance imaging (MRI) of the chest, including the description of new techniques. Over the past decade, this method has evolved considerably because of the development of new equipment, including the simultaneous interconnection of phased-array multiple radiofrequency receiver coils and remote control of the table movement, in addition to faster techniques of image acquisition, such as parallel imaging and partial Fourier acquisitions, as well as the introduction of new contrast agents. All of these advances have allowed MRI to gain ground in the study of various pathologies of the chest, including lung diseases. Currently, MRI is considered the modality of choice for the evaluation of lesions in the mediastinum and in the chest wall, as well as of superior sulcus tumors. However, it can also facilitate the diagnosis of lung, pleural, and cardiac diseases, as well as of those related to the pulmonary vasculature. Pulmonary MRI angiography can be used in order to evaluate various pulmonary vascular diseases, and it has played an ever greater role in the study of thromboembolism. Because cardiac MRI allows morphological and functional assessment in the same test, it has also become part of the clinical routine in the evaluation of various cardiac diseases. Finally, the role of MRI has been extended to the identification and characterization of pulmonary nodules, the evaluation of airway diseases, and the characterization of pleural effusion.

Recent technological and application developments in computed tomography and magnetic resonance imaging for improved pulmonary nodule detection and lung cancer staging

This review compares the emerging technologies and approaches in the application of magnetic resonance (MR) and computed tomography (CT) imaging for the assessment of pulmonary nodules and staging of malignant findings. Included in this review is a brief definition of pulmonary nodules and an introduction to the challenges faced. We have highlighted the current status of both MR and CT for the early detection of lung nodules. Developments are detailed in this review for the management of pulmonary nodules using advanced imaging, including: dynamic imaging studies, dual energy CT, computer aided detection and diagnosis, and imaging assisted nodule biopsy approaches which have improved lung nodule detection and diagnosis rates. Recent advancements linking in vivo imaging to corresponding histological pathology are also highlighted. In vivo imaging plays a pivotal role in the clinical staging of pulmonary nodules through TNM assessment. While CT and positron emission tomography (PET)/CT are currently the most commonly clinically employed modalities for pulmonary nodule staging, studies are presented that highlight the augmentative potential of MR.

Detection of pulmonary nodules with move-during-scan magnetic resonance imaging using a free-breathing turbo inversion recovery magnitude sequence

PURPOSE

Detection of pulmonary metastases is still a challenging task for magnetic resonance imaging (MRI). It was the aim of this study to evaluate the potential of a free-breathing move-during-scan turbo inversion recovery magnitude sequence for the detection of pulmonary nodules.

MATERIALS AND METHODS

The sensitivities and positive-predictive values of 2 radiologists to detect pulmonary nodules in 41 move-during-scan MRI examinations of 38 patients with different malignancies were calculated and subgroup analyses according to lesion size and localization were performed. Multidetector computed tomography served as the standard of reference. Additionally, 6 radiologists rated the confidence for the presence of nodular lesions in 212 regions-of-interest, which were randomly selected to represent lesions of various sizes as well as negative findings. Receiver-operator-characteristic was performed.

RESULTS

Three hundred twenty-one nodules were found in 30 patients by multidetector computed tomography. Sensitivity and specificity of MRI to detect pulmonary nodules larger than 3 mm on a per-patient basis were 81.8% and 94.7%, respectively. On a per-lesion basis, MRI revealed a sensitivity of 79.0% to 80.7% for lesions larger than 3 mm, if high conspicuity ratings were counted as positive, and 84.6%, if medium and high conspicuity ratings were counted as positive. Sensitivity increased uniformly with lesion size, and all lesions larger than 12 mm were detected. Receiver-operator-characteristic analysis revealed a mean accuracy of 0.90 and sensitivities over 90% for lesions larger than 3 mm with a specificity of 96.1%. For lesions larger than 6 mm the accuracy was 0.99.

CONCLUSION

Detection of pulmonary nodules with a move-during-scan turbo inversion recovery magnitude sequence is feasible. Excellent detection of lesions larger than 6 mm is achievable with free-breathing moving-table MRI.

Resection of pulmonary metastases from colorectal carcinoma

Although pulmonary metastases from colorectal carcinoma (CRC) often represent systemic and uncontrolled tumour growth, in a number of patients lung disease is limited and the patient remains well. When the metastases can be removed, long term survival is a possibility, with 5- and 10-year survivals in the order of 44% and 25%. Chemotherapy, the only alternative treatment only very rarely leads to survival beyond 24 months. Pulmonary metastases which are suitable for resection are usually detected on chest radiography, especially when carried out during monitoring of patients. They are rarely a cause of symptoms and the majority of patients have otherwise healthy lungs. CT scans supplemented by PET scans usually confirm the diagnosis, but percutaneous biopsy is sometimes necessary to exclude a primary lung cancer. The criteria for resecting CRC pulmonary metastases are (1) the primary tumour is controlled or is controllable; (2) complete resection is possible; and (3) the patient has adequate pulmonary reserve to tolerate the planned resection. Surgical approaches include posterolateral thoracotomy, staged bilateral thoracotomies, median sternotomy, clamshell incision, and video-assisted thoracic surgery. Each has its advantages and disadvantages. The majority of patients having resection of pulmonary metastases from CRC recover well with very few post-operative complications. Following resection favourable prognostic factors include a long disease-free interval, small number and small size of metastases, a normal carcinoembryonic antigen level, and an absence of concomitant liver metastases and mediastinal lymph node spread. Surgery for pulmonary metastases of CRC remains the best means of local control and the best way to render the patient disease-free. Patients with complete resection of pulmonary metastases have an improved long-term survival when compared to patients with unresected metastases.

MRI of the lung: Value of different turbo spin-echo, single-shot turbo spin-echo, and 3D gradient-echo pulse sequences for the detection of pulmonary metastases

PURPOSE

To compare the value of different MRI sequences of the lung for the detection of pulmonary metastases.

MATERIALS AND METHODS

A total of 28 patients with 225 pulmonary metastases confirmed at multidetector-row computed tomography (MDCT) underwent MRI of the lung, including breathhold T2-weighted single-shot turbo spin-echo (half-Fourier single-shot turbo spin-echo [HASTE] and inversion recovery [IR]-HASTE) and conventional turbo spin-echo (TSE and short-tau inversion recovery [STIR]) sequences, a respiratory- and pulse-triggered black-blood STIR sequence (triggered STIR), and breathhold pre- and postcontrast volumetric interpolated 3D gradient-echo (VIBE) sequences. MR images were reviewed by three independent observers and results were correlated with MDCT, which served as standard of reference. Lesion-to-lung contrast-to-noise ratios (CNRs) and image artifacts were also assessed.

RESULTS

CNRs were highest on TSE images (P < 0.001). Mean sensitivities for lesion detection with triggered STIR, TSE, and STIR were 72.0%, 69.0%, and 63.4%, respectively. With HASTE, IR-HASTE, and pre- and postcontrast VIBE, significantly lower sensitivities were obtained (P < 0.05), although artifacts due to physiological motion were less distinct with these sequences compared to TSE and STIR (P < 0.05).

CONCLUSION

Conventional TSE sequences are more sensitive in depicting pulmonary metastases than single-shot TSE or 3D gradient-echo sequences. Respiratory and pulse triggering can improve lesion detection, but increases acquisition time substantially.

Solitary pulmonary nodule: detection and management

Pulmonary nodules are commonly detected at computed tomography (CT) of the chest. More than 95% are \documentclass[12pt]{minimal} \usepackage{wasysym} \usepackage[substack]{amsmath} \usepackage{amsfonts,amssymb,amsbsy} \usepackage[mathscr]{eucal} \usepackage{mathrsfs} \DeclareFontFamily{T1}{linotext}{} \DeclareFontShape{T1}{linotext}{m}{n}{<-> linotext}{} \DeclareSymbolFont{linotext}{T1}{linotext}{m}{n} \DeclareSymbolFontAlphabet{\mathLINOTEXT}{linotext} \begin{document} $\le $ \end{document} 10 mm; of these more than 95% are benign. Visual detection of pulmonary nodules by human readers is suboptimal, particularly with small nodules \documentclass[12pt]{minimal} \usepackage{wasysym} \usepackage[substack]{amsmath} \usepackage{amsfonts,amssymb,amsbsy} \usepackage[mathscr]{eucal} \usepackage{mathrsfs} \DeclareFontFamily{T1}{linotext}{} \DeclareFontShape{T1}{linotext}{m}{n}{<-> linotext}{} \DeclareSymbolFont{linotext}{T1}{linotext}{m}{n} \DeclareSymbolFontAlphabet{\mathLINOTEXT}{linotext} \begin{document} $\le $ \end{document} 10 mm. Computer-assisted detection can improve sensitivity and diagnostic confidence. Due to the high proportion of malignant lesions in nodules >10 mm immediate, often invasive work-up is required including contrast-enhanced dynamic CT, positron emission tomography (PET) or biopsy. However, in nodules \documentclass[12pt]{minimal} \usepackage{wasysym} \usepackage[substack]{amsmath} \usepackage{amsfonts,amssymb,amsbsy} \usepackage[mathscr]{eucal} \usepackage{mathrsfs} \DeclareFontFamily{T1}{linotext}{} \DeclareFontShape{T1}{linotext}{m}{n}{<-> linotext}{} \DeclareSymbolFont{linotext}{T1}{linotext}{m}{n} \DeclareSymbolFontAlphabet{\mathLINOTEXT}{linotext} \begin{document} $\le $ \end{document} 10 mm the high proportion of benign lesions requires a non-invasive work-up usually based on follow-up with unenhanced CT. Invasive procedures are only required for growing nodules. Stable nodules require further follow-up and decreasing nodules are considered benign.

Detection of small pulmonary nodules in high-field MR at 3 T: evaluation of different pulse sequences using porcine lung explants

To evaluate two MR imaging sequences for the detection of artificial pulmonary nodules inside porcine lung explants. 67 agarose nodules ranging 3-20 mm were injected into ten porcine lungs within a dedicated chest phantom. The signal on T1-weighted images and radiopacity were adjusted by adding 0.125 mmol/l Gd-DTPA and 1.5 g/l of iodine. A T1-weighted three-dimensional gradient-echo (T1-3D-GRE; TR/TE:3.3/1.1 ms, slice:8 mm, flip-angle:10 degrees ) and a T2-weighted half-Fourier fast-spin echo sequence (T2-HF-FSE; TR/TE:2000/66 ms, slice:7 mm, flip-angle:90 degrees ) were applied in axial orientation using a 3-T system (Intera, Philips Medical Systems, Best, The Netherlands), followed by CT (16x0.5 mm) as reference. Nodule sizes and locations were assessed by three blinded observers. In nodules of >10 mm, sensitivity was 100% using 3D-GRE-MRI and 94% using the HF-FSE sequence. For nodules 6-10 mm, the sensitivity of MRI was lower than with CT (3D-GRE:92%; T2-HF-FSE:83%). In lesions smaller than 5 mm, the sensitivity declined to 80% (3D-GRE) and 53% (HF-FSE). Small lesion diameters were overestimated with both sequences, particularly with HF-FSE. This study confirms the feasibility of 3 T-MRI for lung nodule detection. In lesions greater than 5 mm, the sensitivity of the 3D-GRE sequence approximated CT (>90%), while sensitivity and PPV with the HF-FSE sequence were slightly inferior.

Total-body MR-imaging in oncology

Although MRI is an effective modality in oncology, state-of-the-art total-body MRI (TB-MRI) in the past was infeasible in the diagnostic work-up, due to the need for repeated examinations with repositioning and separate surface coils to cover all body parts. To overcome this limitation, either a moving table platform in combination with the body-coil or a special designed rolling table platform with one body phased-array coil have been implemented with promising results for both tumor staging and metastases screening. Since 2004, state-of-the-art TB-MR imaging with high spatial resolution has become feasible using a newly developed 1.5 Tesla TB-MRI system with multiple receiver channels. This review gives an overview based on the recent literature as well as our own experience concerning the possibilities, challenges, and limitations of TB-MRI in oncology, emphasizing both oncological staging and early tumor detection in asymptomatic subjects.

[Radiological diagnosis of pulmonary metastases: imaging findings and diagnostic accuracy]

Pulmonary metastases typically present as mostly multiple and bilateral, well-defined, non-calcified pulmonary nodules with predominantly basal and peripheral location. Ill-defined, cavitating, calcified and endobronchial metastases are uncommon. In the absence of pathognomonic findings precise differentiation from other-even benign-pulmonary nodules is almost impossible. Demonstration of contrast enhancement at CT or MRI or evidence of growth at serial examinations support the diagnosis of pulmonary metastases. In uncertain cases percutaneous fine-needle aspiration or cutting needle biopsy will allow diagnosis with acceptable risk of complications and patient discomfort. The only relatively common complication of pneumothorax can and should be controlled by the interventional radiologist by aspiration or drainage.

HASTE MRI Versus Chest Radiography in the Detection of Pulmonary Nodules: Comparison with MDCT

OBJECTIVE

The purpose of our study was to compare the diagnostic accuracy of an ultrafast ECG-triggered black blood-prepared HASTE sequence with chest radiography for the detection of pulmonary nodules. SUBJECTS AND METHODS. Sixty-four patients with various primary malignancies who had undergone radiography and MDCT of the chest also underwent ECG-triggered black blood-prepared HASTE MRI of the lung. MR images and radiographs were interpreted separately. The number, location, and size of detected lesions were recorded, and each hemithorax was classified as affected or not affected on the basis of a grade reflecting the conspicuity of nodular involvement. Sensitivity, specificity, and positive and negative predictive values for the detection of pulmonary nodules with diameters of 5 mm or larger were determined, using MDCT findings as the standard of reference. Lesions with diameters smaller than 5 mm were not evaluated. Additional lesion-by-lesion comparisons between MDCT and MRI findings were performed.

RESULTS

MDCT confirmed pulmonary lesions in 32 patients, whereas HASTE MRI revealed lesions in 30 patients and chest radiography, in 19 patients. MDCT revealed 226 nodules in 32 patients, whereas MRI HASTE revealed 227 lesions in 30 patients. Conspicuity scale-based sensitivity and specificity for chest radiography were 55.8% and 92.4%, respectively, whereas HASTE MRI had a sensitivity of 93.0% and a specificity of 96.2%. Positive and negative predictive values for chest radiography were 80% and 79.3%, respectively, and for HASTE MRI, 93.0% and 96.2%, respectively. The sensitivity of HASTE MRI increased with lesion size, ranging from 94.9% for nodules between 5 and 10 mm in diameter to 100% for lesions exceeding 3 cm in diameter.

CONCLUSION

ECG-triggered black blood-prepared HASTE MRI is reliable for detecting pulmonary nodules exceeding 5 mm and has proven significantly more accurate than conventional chest radiography. The technique appears useful as an adjunct to MRI of the heart, great vessels, or chest, potentially increasing the diagnostic yield of MRI examinations.

Simulated pulmonary nodules implanted in a dedicated porcine chest phantom: sensitivity of MR imaging for detection

PURPOSE

To evaluate the diagnostic accuracy of common magnetic resonance (MR) imaging sequences for detection of small pulmonary nodules by using a chest phantom and porcine lungs containing simulated lesions.

MATERIALS AND METHODS

Fourteen porcine lungs containing 366 porcine myocardial tissue implants were inflated inside a phantom. Two-dimensional (2D) and three-dimensional (3D) gradient-echo (GRE), T2-weighted turbo spin-echo (SE), and T2-weighted single-shot SE train MR sequences were performed. Spiral computed tomography (CT) was performed for comparison. Blinded observers read the images and recorded the sizes and locations of visible nodules by consensus. The sensitivity of each imaging method for depicting single nodules of given sizes was calculated. Specificities, positive predictive values (PPVs), and negative predictive values (NPVs) for detection of one or more nodules of various sizes were calculated.

RESULTS

Sensitivities of 3D GRE, 2D GRE, T2-weighted turbo SE, and T2-weighted single-shot SE train MR imaging and of CT were 0.50, 0.40, 0.12, 0.00, and 0.55, respectively, for detection of 1.4-mm nodules and 0.88, 0.84, 0.69, 0.06, and 0.96, respectively, for detection of 4.2-mm nodules. The 95% CIs for CT and GRE MR imaging overlapped, but those for turbo SE and single-shot SE train MR imaging differed significantly (P <.05). For detection of nodules larger than 5 mm, all examinations except single-shot SE train MR imaging yielded a specificity, PPV, and NPV of 1.00 each. For detection of nodules smaller than 5 mm, diagnostic accuracy of 3D GRE MR imaging was high: Specificity, PPV, and NPV all were approximately 0.90. Two-dimensional GRE MR imaging results were influenced by false-positive findings: Specificity was 0.64; PPV, 0.74; and NPV, 1.00.

CONCLUSION

Common MR imaging sequences such as 3D GRE have high diagnostic accuracy in depicting small pulmonary nodules when artifacts from cardiac and respiratory motion are absent.

MR imaging of the chest using a contrast-enhanced breath-hold modified three-dimensional gradient-echo technique: comparison with two-dimensional gradient-echo technique and multidetector CT

OBJECTIVE

The purpose of this study was to assess the feasibility of performing MR imaging of the chest using a fat-suppressed gadolinium-enhanced modified three-dimensional (3D) gradient-echo technique with a volumetric interpolated breath-hold (VIB) sequence compared with using a standard two-dimensional (2D) breath-hold gradient-echo technique. MR images obtained using both techniques were compared with multidetector CT (MDCT) scans.

SUBJECTS AND METHODS

Paired gadolinium-enhanced 2D gradient-echo and 3D gradient-echo VIB images were acquired in 15 consecutive patients with suspected intrathoracic abnormalities. MDCT scans were available for comparison in 12 patients. Two reviewers independently analyzed the MR images obtained using the two techniques for overall quality, the degree of artifacts, and visibility of mediastinal or parenchymal abnormalities. The detectability of lesions on the 3D gradient-echo VIB images and 2D gradient-echo images was compared with the detectability of lesions on CT scans obtained in nine patients.

RESULTS

In all cases, the MR images obtained using the 3D gradient-echo technique with the VIB sequence were rated superior to those obtained using the 2D gradient-echo technique for quality, depiction of mediastinal structures, and clarity of pulmonary vessels and central airways. On the 3D gradient-echo VIB images, the degree of phase artifacts was lower (p < 0.001), but the degree of pixel graininess was higher (p < 0.05). Detectability, confidence and conspicuity levels, and marginal delineation of the pulmonary lesions were rated higher statistically on the 3D gradient-echo VIB images than on the 2D gradient-echo images. Of the 31 solid pulmonary abnormalities depicted on MDCT, 27 (87.1%) were detected on the 3D gradient-echo VIB images, and 21 (67.7%) were seen on the 2D gradient-echo images (p < 0.05). The 3D gradient-echo VIB images showed all 14 mediastinal lesions (100%) seen on MDCT, whereas the 2D gradient-echo images showed 12 (85.7%) of the 14 lesions (p > or = 0.05).

CONCLUSION

The gadolinium-enhanced modified 3D gradient-echo technique with the VIB sequence provides MR images that are superior in quality, have significantly fewer artifacts, and have a higher sensitivity for the detection of intrathoracic lesions compared with images obtained using the standard 2D gradient-echo technique.

Contrast-enhanced MRI of the lung

The lung has long been neglected by MR imaging. This is due to unique intrinsic difficulties: (1) signal loss due to cardiac pulsation and respiration; (2) susceptibility artifacts caused by multiple air-tissue interfaces; (3) low proton density. There are many MR strategies to overcome these problems. They consist of breath-hold imaging, respiratory and cardiac gating procedures, use of short repetition and echo times, increase of the relaxivity of existing spins by administration of intravenous contrast agents, and enrichment of spin density by hyperpolarized noble gases or oxygen. Improvements in scanner performance and frequent use of contrast media have increased the interest in MR imaging and MR angiography of the lung. They can be used on a routine basis for the following indications: characterization of pulmonary nodules, staging of bronchogenic carcinoma, in particular assessment of chest wall invasion; evaluation of inflammatory activity in interstitial lung disease; acute pulmonary embolism, chronic thromboembolic pulmonary hypertension, vascular involvement in malignant disease; vascular abnormalities. Future perspectives include perfusion imaging using extracellular or intravascular (blood pool) contrast agents and ventilation imaging using inhalation of hyperpolarized noble gases, of paramagnetic oxygen or of aerosolized contrast agents. These techniques represent new approaches to functional lung imaging. The combination of visualization of morphology and functional assessment of ventilation and perfusion is unequalled by any other technique.

Secondary pulmonary malignancy

Patients with pulmonary metastases were previously relegated to palliative medical management. Since the first metastasectomies in the nineteenth century, general acceptance of this technique has occurred. Although, initially, indications for resection of pulmonary metastases were limited to patients with solitary nodules, over time, indications have broadened to include multiple lesions, recurrent disease, and nearly all histologies. With appropriate patient selection and the absence of extrathoracic disease, survival may be improved. For patients with disseminated and symptomatic disease, surgical therapy may also provide some relief.

Breath-hold 3D gradient-echo MR imaging of the lung parenchyma: evaluation of reproducibility of image quality in normals and preliminary observations in patients with disease

This study evaluates the reproducibility and image quality of a three-dimensional (3D) gradient-echo sequence for imaging the lung parenchyma, with and without gadolinium administration, using a 2D spoiled gradient-echo sequence for comparison. Twenty patients without lung disease (normals) and five patients with lung disease (lung disease) underwent paired 2D and 3D gradient-echo sequences, without contrast (24 patients) and with contrast (18 patients). Images were retrospectively reviewed independently in a blinded fashion by two investigators. Artifacts and demonstration of central lung, peripheral lung, heart, pulmonary arteries, and esophagus were evaluated. Image quality of the central lung was rated as fair or good in 5 and 4 (reader one and two) patients with non-contrast 2D gradient-echo, 24 and 25 patients with non-contrast 3D gradient-echo, 3 and 1 patient(s) with contrast-enhanced 2D gradient-echo, and 19 and 19 patients with contrast-enhanced 3D gradient-echo imaging. Differences in image quality between 2D and 3D sequences were significant (P < 0.001). Heart-related phase artifacts were negligible in 2 and 0 patients with non-contrast 2D gradient-echo, 23 and 25 patients with non-contrast 3D gradient-echo, 0 and 0 patients with contrast-enhanced 2D gradient-echo, and 17 and 19 patients with contrast-enhanced 3D gradient-echo imaging. Differences in heart-related phase artifact in the central lung between 2D and 3D sequences were significant (P = 0.001). Infiltrates, lung cancer, and pulmonary metastasis were better shown on the gadolinium-enhanced 3D gradient-echo sequences than on the other sequences. Breath-hold 3D gradient-echo imaging results in good image quality and negligible image artifacts and is superior to 2D spoiled gradient-echo imaging. Preliminary results in patients with disease appear promising.

MR imaging of focal lung lesions: elimination of flow and motion artifact by breath-hold ECG-gated and black-blood techniques on T2-weighted turbo SE and STIR sequences

Respiratory and cardiac motion correction may result in better turbo spin-echo (SE) imaging of the lung. To compare breath-hold cardiac-gated black-blood T2-weighted turbo SE and turbo short-inversion-time inversion-recovery (STIR) magnetic resonance (MR) imaging pulse sequences with conventional breath-hold turbo SE and half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences for lesion conspicuity of focal lung lesions, 42 patients with focal lung lesions were prospectively studied with MR imaging at 1.5 T. Helical computed tomography was used as a reference. In comparison with the conventional breath-hold turbo SE sequence, all black-blood sequences had fewer image artifacts arising from the heart and blood flow. The overall image quality for the black-blood turbo SE and turbo STIR sequences was superior to that for the breath-hold turbo SE and HASTE sequence (P < 0.01). Not only focal lung lesions but also surrounding inflammatory changes were clearly visualized with these two sequences. With the HASTE sequence, although several slices could be obtained in one breath-hold, both the tumor and vessels appeared blurred. We conclude that T2-weighted turbo SE and turbo STIR imaging of the lung with effective suppression of flow and motion artifacts provide high-quality images in patients with focal lung lesions.

Total-body echo-planar MR imaging in the staging of breast cancer: comparison with conventional methods--early experience

PURPOSE

To test breast cancer staging with total-body echo-planar magnetic resonance (MR) imaging.

MATERIALS AND METHODS

Nineteen patients with newly diagnosed breast cancer were imaged by using a 1.5-T echo-planar MR system. By using a table sweep method, 180 contiguous axial images were obtained from the cranial vertex through the feet with T2-weighted spin-echo and inversion-recovery sequences. Results were compared with those of conventional imaging. Therapeutic decisions based on echo-planar MR imaging and conventional imaging results were compared. Diagnostic truth was determined by means of tissue diagnosis, further imaging findings, and follow-up findings (median, 18 months).

RESULTS

Staging with total-body echo-planar MR imaging was correct in 18 patients (95%)--eight with metastases and 10 without--while staging with conventional imaging was correct in 15 patients (79%). In one patient, both echo-planar MR imaging and conventional imaging findings incorrectly indicated probable metastases. In one patient thought to have bone metastases at conventional imaging, echo-planar MR imaging findings were normal, which was correct. Two patients with stage IV disease were not suspected to have disease at conventional imaging: One had liver involvement and the other had skeletal metastases. The therapeutic decisions in these two patients were altered by the echo-planar MR imaging results.

CONCLUSION

Total-body echo-planar MR imaging was at least as accurate as conventional imaging for staging newly diagnosed breast cancer and was faster, simpler, and completely noninvasive.

Multidisciplinary management of metastatic colorectal cancer

When colorectal cancer metastasizes to distant organs, usually multiple sites are involved and treatment consists primarily of systemic chemotherapy and supportive care. Chemotherapeutic agents effective against metastatic colorectal cancer include 5-fluorouracil, often used in combination with leucovorin or methotrexate, and irinotecan (CPT-11). Median survival with optimal chemotherapy regimens ranges from 10 to 15 months. Less frequently, colorectal cancer metastasizes only to the liver or lung. In a minority of these cases, surgical resection can be performed and results in a median survival of 28-46 months for hepatic resections and 24-25 months for pulmonary resections. Five-year survival rates range from 24 to 38% and 21 to 44% for hepatic and pulmonary resections, respectively. For isolated liver metastases that are not surgically resectable, other regional therapies that can be considered are hepatic cryosurgery, radiofrequency ablation, and hepatic arterial infusion chemotherapy. Median survival following cryosurgery is between 26 and 30 months, while median survival following radiofrequency ablation has not been established in large series. Hepatic arterial infusion chemotherapy, especially with newer combination drug regimens, may increase survival in patients with isolated liver metastases compared to systemic chemotherapy, but this must be confirmed in randomized, prospective trials. Colorectal cancer metastases to the brain can be treated with radiation therapy or surgical resection, but median survival with treatment is less than one year.

Evaluation of solitary pulmonary nodules with dynamic contrast-enhanced MR imaging--a promising technique

The evaluation of a solitary pulmonary nodule (SPN) is one of the most frequently encountered challenges in thoracic radiology. In addition to a "state-of-the-art" evaluation of SPNs with CT and biopsy techniques, recently the assessment of the enhancement characteristics with iodinized contrast agents has shown its potential to improve the characterization of SPNs. We investigated whether dynamic contrast-enhanced MRI is suitable to assess the degree and kinetics of MR contrast enhancement and whether this technique could help in the noninvasive specification of SPNs. We studied prospectively 21 patients with SPNs. T1-weighted and proton density-weighted spoiled gradient-echo breath-hold images (2D-FLASH) were obtained before and after the administration of Gd-DTPA in a standard dosage of 0.1 mmol/kg body weight. The maximum enhancement and the initial velocity of contrast uptake were assessed and correlated with pathohistological findings. To quantify contrast enhancement, we used the relative signal intensity increase (S(rel)) and the recently introduced enhancement factor (EF) and contrast uptake equivalent (CE). Dynamic contrast-enhanced MRI proved to be well suited for the assessment of the contrast enhancement characteristics of SPNs. Significant differences were found in the degree and kinetics of contrast enhancement for specific types of nodules. Malignant neoplastic SPNs enhanced stronger and faster than benign neoplastic SPNs. The strongest and fastest enhancement, however, was found in a benign type of nodules where histology revealed inflammatory/fibrous lesions. These differences in contrast enhancement between the different pathohistological groups were more significant when EF and CE rather than S(rel) was used for the quantification of contrast enhancement. The results of this study indicate a potential role for dynamic contrast-enhanced MRI in the preoperative noninvasive evaluation of SPNs using EF and CE as contrast uptake assessment parameters.

Initial and reoperative pulmonary metastasectomy: indications, technique, and results

The ability to predict which patients will derive a survival benefit from pulmonary metastasectomy is limited. Most patients remain asymptomatic until the disease becomes advanced, and therefore computerized tomography (CT) of the chest has become the standard of care for follow-up of patients at risk for pulmonary metastases. The most important predictor of post-thoracotomy survival in patients at the National Cancer Institute with soft tissue, osteogenic, and pediatric sarcomas as well as melanoma and renal cell carcinoma has been the ability to render the patient disease-free. Tumor histology, disease-free interval, and possibly number of nodules are also determinants of survival. Median sternotomy is the preferred approach for initial and repeat metastasectomies and every effort should be made to preserve pulmonary parenchyma. Resection of pulmonary metastases has become an accepted therapeutic modality, but selection of surgical candidates, and operative planning needs to be individualized.